go up in teeth or down?

[85 250sx]

i have a 86 250r and was wondering what would get me a faster 300' drag time going up in teeth to get topend speed or going down it teeth for mor acceleration? what do you guys thing every thing on the bike is stock

[NOS_350X]

Depends on how fast you shift, size of tires, engine, where your powerband hits, and type of ground your on. Too many factorst to tell you what to do. Just start trying diffrent stuff until you find out what works for you.

[TimSr]

Since you normally dont start in first gear, and you are not going to top out in 300', a sprocket change isnt going to do anything for you. Gearing has nothing to do with acceleration other than the distance from a dead start to where the clutch is all the way out in first gear, and it has nothing to do with speed until it tops out.

[KASEY]

with a stock bike gearing is real important,,,but you really need to know you bike to be able to determine whether it might pull a little better if you gained a half a gear or lose a half a gear,,, highly modded bikes gearing is not so critical. cause they can overcome gearing with brute power. think about it when your riding,,, sometimes you will see that if you had a half a gear change it would be better,,,,,

[OldSchoolin86]

a sprocket change isnt going to do anything for you. Gearing has nothing to do with acceleration
Ouch! Gearing is crucial for acceleration.
Multiplying torque = equals harder and faster acceleration but you will loose top end (the trade off).

[RacerRichie]

Ouch! Gearing is crucial for acceleration.
Multiplying torque = equals harder and faster acceleration but you will loose top end (the trade off).


I second this. A lot can be gained depending on what type of terrain you are in. example: When I ride in the woods, I like to drop a tooth to get the most out of my machine and power output.

[HaggLE]

Gear it so that you are in top gear and are looking for another gear just at or just after the finish line.

[TimSr]

Ouch! Gearing is crucial for acceleration.
Multiplying torque = equals harder and faster acceleration but you will loose top end (the trade off).

Reread and think about the ENTIRE sentence, but yes, I misused "gearing" and should have said "sprockets". SPROCKETS have nothing to do with acceleration other than the distance from a dead start to where the clutch is all the way out in first gear, and it has nothing to do with speed until it tops out.

Changing gearing is called "shifting", and Ill concede you accelerate best if you shift in the right gear for whatever RPMs your motor happens to be turning at the moment. The best way to do that is by using the shifter not changing sprockets. I didnt go into details, as I didnt want to make a simple post complicated but Kasey hit on a point when he mentioned gaining or losing a 1/2 gear can sometimes be helpful. Not common with a 6 speed, but I have run into it on a 5 speed. In other words, when 1st is too low, and 2nd is too high, sprocket changes can useful in moving 2nd down half a notch or first up a notch. That halfway in between gear thing can also be optimized for cornering, but again, I didnt go there because I didnt think he'd encounter many corners on a drag strip. And if you really want to get technical, the spacing between the gears is often different between the lower gears and the higher gears, and moving the entire gearbox range can buy a fraction of a second, but since he was asking about specific circumstances, an 86 250R in a 300ft drag strip, I didnt go into trail riding, hillclimbing, mx cornering or anything else. He simply wanted to know if a sprocket change will give him a better time on a 300' drag, and my answer is no, unless you are starting in 1st gear, or completely topping out. Once you are moving, SPROCKETS have no effect on how fast you accelerate, but yes "gearing" meaning shifting into the correct gear to keep it in the power band does. By the question posted, I assume he is new to drag racing, and that he will gain a lot more time by practicing starting in different gears, to see what works best with the particular tires he is running, and on the surface he is running. If you get your technique perfected, and decided something less than a full shift in either direction, might improve things, then you can alter sprockets to move you to a spot in between gears, and whether you go up or down wont matter, again, unless you run out of gears in either direction.
I once blew out 1st gear on my TriZ and ran an entire MX season, by simply gearing down with sprockets to where 2nd gear matched where first gear used to be. Did dropping two teeth on the front sprocket make me accelerate faster? Of course not, because instead of running the whole track in 2nd, 3rd, 4th and once in a while 5th, I was running it in 3rd 4th 5th, and once in a while 6th. I stand by my original statement, substituing the word "sprockets" for "gearing".

[OldSchoolin86]

Reread and think about the ENTIRE sentence, but yes, I misused "gearing" and should have said "sprockets". SPROCKETS have nothing to do with acceleration other than the distance from a dead start to where the clutch is all the way out in first gear, and it has nothing to do with speed until it tops out.

Changing gearing is called "shifting", and Ill concede you accelerate best if you shift in the right gear for whatever RPMs your motor happens to be turning at the moment. The best way to do that is by using the shifter not changing sprockets. I didnt go into details, as I didnt want to make a simple post complicated but Kasey hit on a point when he mentioned gaining or losing a 1/2 gear can sometimes be helpful. Not common with a 6 speed, but I have run into it on a 5 speed. In other words, when 1st is too low, and 2nd is too high, sprocket changes can useful in moving 2nd down half a notch or first up a notch. That halfway in between gear thing can also be optimized for cornering, but again, I didnt go there because I didnt think he'd encounter many corners on a drag strip. And if you really want to get technical, the spacing between the gears is often different between the lower gears and the higher gears, and moving the entire gearbox range can buy a fraction of a second, but since he was asking about specific circumstances, an 86 250R in a 300ft drag strip, I didnt go into trail riding, hillclimbing, mx cornering or anything else. He simply wanted to know if a sprocket change will give him a better time on a 300' drag, and my answer is no, unless you are starting in 1st gear, or completely topping out. Once you are moving, SPROCKETS have no effect on how fast you accelerate, but yes "gearing" meaning shifting into the correct gear to keep it in the power band does. By the question posted, I assume he is new to drag racing, and that he will gain a lot more time by practicing starting in different gears, to see what works best with the particular tires he is running, and on the surface he is running. If you get your technique perfected, and decided something less than a full shift in either direction, might improve things, then you can alter sprockets to move you to a spot in between gears, and whether you go up or down wont matter, again, unless you run out of gears in either direction.
I once blew out 1st gear on my TriZ and ran an entire MX season, by simply gearing down with sprockets to where 2nd gear matched where first gear used to be. Did dropping two teeth on the front sprocket make me accelerate faster? Of course not, because instead of running the whole track in 2nd, 3rd, 4th and once in a while 5th, I was running it in 3rd 4th 5th, and once in a while 6th. I stand by my original statement, substituing the word "sprockets" for "gearing".
TimSr I completely respect you but this is all wrong. I wouldn't bother but 85 250sx has a good question and he needs a good answer. Gearing inn this case is a reference to your sprocket ratio. Changing that ratio is a direct connection to changing your acceleration. It's flat out physics, it kind of hard to beat that. Gearing IS crucial to running a good drag race. I wasn't talking about MX or XC either but it still helps there too.

Here's a quote from Renthal sprockets:

Setting up the gearing of any vehicle is a trade-off between acceleration and top speed.

Gearing a bike up to produce higher top speed with less acceleration is done using a larger countershaft (gearbox) sprocket or a smaller rear sprocket.

Gearing a bike down giving it more acceleration with lower top speed is done using a smaller countershaft (gearbox) sprocket or a larger rear sprocket.

Take a machine that has hi/lo range. When you go from hi to lo range what happens? You change the gearing so you have tons of more torque. What happens to each gear? All of a sudden instead of taking a couple seconds to run out the selected gear it's almost instant and you find yourself shifting a lot faster and more. This is the same thing if you drop a tooth in the front or add some in the rear. You're not just "altering sprockets to move you to a spot in between gears", you’re adding more torque and making the time in your gears shorter as a result of it. It's the same as changing rear end gears in a car.

Here's a quote from Performance gearing:

Increase the torque delivered to the ground for much faster acceleration

Changing your cars gearing is one of the most effective performance improvements you can make for the money. For example, swapping from a 3.15 to 3.46 ratio will give your car 10% more torque delivered to the rear wheels!

We can bring in several people from the automotive world that would agree with this one. It's all the same whether you’re on 2, 3 or 4 wheels. If you change your gearing (sprockets), you’re going to change your acceleration.

Some bikes are just set up better from the factory then others so you may not need to change anything but to answer your question 85 250sx, if you want to increase acceleration then you would drop teeth in the front or add teeth in the back. The front will drastically change your ratio compared to the rear so here's a good chart to that lays out the changes that will happen when swapping sprockets. Good Luck.

http://www.renthal.com/site/resources/ratios.htm

[crackshot]

run nitromethane and methonol in gas then put nitrous bottle on trike. you will fly no matter what gearing you use!

[NOS_350X]

run nitromethane and methonol in gas then put nitrous bottle on trike. you will fly no matter what gearing you use!

Ya and also you can learn how to rebuild a bike after you run it for 10 minutes.

Rember this 1 tooth in the front = 5 or 6 in the back. also to get more torque you gear down the front gear and gear up the back, for more top speed gear up the front and down the back. This might help you out some. Another little helpful fact is 1horse(horsepower)=9pounds.

I recommend to run it a few times and decide how many times you want to shift. You want to be at a shifting point right at the end of the drag without reving out or bogging down any. For example my brother and i on our 350X's, i have my X geared down with 20" turf tamers, and my brother has 26" baloon tires with stock gearing. When we drag he shifts less but i'm slightly faster, on top speed he is about 10 mph faster. Decide how you want to shift and gear accordingly.

[TimSr]

I guess Im looking at too big of a picture here, and I dont know any other way to explain it. Your sprockets are only half of your final drive ratio. The gear box is also part of that picture. What gear you are in determines your final ratio every bit as much as sprocket size. You change final drive ratio each time you shift. You can easily offset any sprocket change by shifting gears. I used the example of dropping two teeth on the front sprocket, and running everything normally, only a gear higher.

If I do 2nd gear starts, with a 13 tooth sprocket, is it your opinion that if I drop to 11 teeth and start in 3rd gear, that I will accelerate faster because of the smaller sprocket? My position is that I have essentially the same final gear ratio, and it will make no difference at all. I dropped gearing on the sprockets and clicked the shifter which nullified my sprocket change. How can it accelerate faster when its got the same final drive ratio? If I start out in 4th gear, the smaller sprocket, wont I accelerate slower, even with the smaller sprocket? If your theory is correct, then I should be able to drop 2 teeth in the front, drop 7 teeth in the rear, and gain both speed an acceleration. You are right, it is simple physics, and you cant say sprocket ratios change gearing without taking into account that its connected to a gearbox that changes gearing a lot more than a sprocket change. You shift gears to change gearing ratios. Changing sprockets is for when you need to operate outside the limitations of your gearbox, and again I say will do nothing for you unless you need to operate beyond the limitations of your gearbox, or in between the shift points. If you are doing 2nd gear starts, and you need to gear lower, it makes a lot more sense to shift into first when you start instead of changing the sprockets to make 2nd gear the same ratio as first. Sprocket changes are for when you need something in between 1st and 2nd, or lower than first.

[a-camp]

Ive asked Kasey this one time but I race on a steep hill. I think you should drop a tooth in the rear if your racing on flat ground. If your on a hill racing you may try to go up a tooth on a stock bike. Just my best guesse I dont know everthing.

[Studytime]

Guys... guys...

You're trying to factor in TOO many variables. Whenever you talk about a gearing change, you don't take the ratioes of 1,2,3,4,5 & 6 into play. We should be thinking of more of a "final drive" ratio.

Does more aggressive gearing make you accelerate quicker? Well, that depends on several factors. To begin, my post I just tried an el quicko search on the net and could not readily find trike gearin so I'll make my post with references to my truck.

My gears are 2.48, 1.48, and 1:1 respectively. That's first, second and drive with my turbo 400 transmission. I currenly ran a 2.73:1 ratio and as stated in this thread, this provided less torque than the 3.42:1 gears I run now. This is all simple math to calculate the speed attainable in each gear. It's all linear- that is speed/rpm increases at a constant rate as opposed to a rate that starts off increasing slowly and then increases "exponentially".

Yes, I could start off in second gear with a 4.56:1 ring and pinion and it would be the exact same as starting in FIRST with a 2.73:1 gear. Which would be better, well they are the exact same thing.

Also, you WILL (this isn't up for question) gain the most acceleration when you are at peak torque in any gear. This is why a gear change may help in some instances.

Anyway, remember when talking about a gear change to only think about how it changes final drive ratio if you want to use it in a comparison to another trike.

Will having more aggressive gearing help you accelerate faster? Well, it would in a perfect ideal world, but we don't live there. With more aggressive gearing you'll notice the tendency for your tires to slip more so you may be wasting your time. This would be the reason why some people start off "on the line" in second gear.

I don't have any hard numbers on, say the 250r's, gearing. If someone has these ratios please add them to this thread.

Remember that it's all linear computations. The equation is real simple as to how to figure out top speed in any gear. Just use some simple logic and you can derive it yourself.

For what it's worth, my 3.42 gears on the street consistantly outperform other vehicles with 3.73/4.11 gears. Why? Well, I don't launch as hard and I maintain ideal traction and can "hold" first longer than my competition.

Yes, gearing down will help you lauch the bike, but it will be easier to spin the tires in the sand. Gearing so that you're in the top of 6th by 300' would probably be too aggressive. The good news is that sprockets are cheap and seeing what works best for you is fun. Good luck.

I recommend going UP a tooth in the front, launching in first, and practicing a lot however, but that's just me.

Studytime

[KASEY]

guys listen to tim sr. he is right ..... the ONLY helpful sprocket change would be a point BETWEEN GEARS,,,, otherwise you just shift,,, that is very simple,,,

on my 500 for drag racing i only gear to come out of the hole,,, i have enough power and gear to go out the back ,, but sometimes i need a tooth or two to get the start where i am comfortable,,, also nobody has hit on tire pressure either,,, a few pounds in a tire can give you a fraction of a gear too,,,, there are lotsa variables

SO,,, on a stock bike where it might not have thepower to pull 4th or 5th out the back ,, 300' is not very long you might need a half a gear to be in the best position in your powerband to get out the quickest,,, and with a run only lasting a few seconds ,,,, THINK FAST!!! :D :D :D

[RideRed250R]

i wish i could stay quiet but...
this is wat i would use k i have seen several atc250R's-330Rs runnin this set up and they were smokein 370 banshees and all the way up to the 410 banshee, take and go to a 40 rear and a 12 front with 21inch 8 paddle haulers, u wont spin to bad and ahve the acceleration factor also
i run 13/39 with 21inch 8 paddle haulers
adam

[OldSchoolin86]

Your sprockets are only half of your final drive ratio. The gear box is also part of that picture. What gear you are in determines your final ratio every bit as much as sprocket size. You change final drive ratio each time you shift.
That's not your finial drive ratio.

If I do 2nd gear starts, with a 13 tooth sprocket, is it your opinion that if I drop to 11 teeth and start in 3rd gear, that I will accelerate faster because of the smaller sprocket?
That's all you, I never said that.

My position is that I have essentially the same final gear ratio, and it will make no difference at all. I dropped gearing on the sprockets and clicked the shifter which nullified my sprocket change. How can it accelerate faster when its got the same final drive ratio?
It doesn't have the same final drive ratio. Let's say you have a 15t front and a 36t rear. That is a 2.40 final drive ratio. Now lets say you swap in a 12t front and a 40t rear. You now would have a 2.67 final ratio. By doing this you have now added 11.25% more torque going to your tires in every gear. This has also made the time you are in each gear 11.25% less. Okay, now that know how much more torque you are adding for every gear you shift into you can see that your acceleration will be greater. You are appling more power to your wheels. As studytime said though, traction is an issue to deal with to but that is another variable not needed at the moment

When you cahnge your final drive If I start out in 4th gear, the smaller sprocket, wont I accelerate slower, even with the smaller sprocket? If your theory is correct, then I should be able to drop 2 teeth in the front, drop 7 teeth in the rear, and gain both speed an acceleration.
I'm really hoping this is a sence of humor here. I'm sure it is because we both know dropping teeth in the front and rear won't get you both speed and torque, lmao. That theory is all yours.

You are right, it is simple physics, and you cant say sprocket ratios change gearing without taking into account that its connected to a gearbox that changes gearing a lot more than a sprocket change. You shift gears to change gearing ratios.
See the above explination on how it effects every gear.

Changing sprockets is for when you need to operate outside the limitations of your gearbox, and again I say will do nothing for you unless you need to operate beyond the limitations of your gearbox, or in between the shift points. If you are doing 2nd gear starts, and you need to gear lower, it makes a lot more sense to shift into first when you start instead of changing the sprockets to make 2nd gear the same ratio as first. Sprocket changes are for when you need something in between 1st and 2nd, or lower than first.Sure it's a great way to get you a better starting point but that's only one benifit of what your doing. You have to understand that your finial drive ratio affects how much torque you apply to the ground. Changing your final drive ratio for more torque equals faster acceleration which equals less top speed. Changing your final drive ratio for less torque equals slower acceleration which equals more top speed.

[Mr. Sandman]

Ok guys, attached is a final drive ratio gearing chart. As previously stated by KASEY and others, tire sizes and pressures also affect the final drive ratio. Red Rider has a chart that figures the tire sizes in, so hopefully he'll post it.

[Studytime]

I was asking for a chart that tells the ratioes of the actual transmission gears. The posted ones are just simple division.

Studytime

[Billy Golightly]

Ok, guys from my ATC200X service manual:


Primary Reduction: 3.33
Gear Ratio #1: 2.769
Gear Ratio #2: 1.941
Gear Ratio #3: 1.450
Gear Ratio #4: 1.130
Gear Ratio #5: 0.923

Final Reduction: 3.33




Now, I dont know, But I'm inclined to think that if you change the external sprockets (The main shaft, and the axle one) that you will be changing the # of times the wheels rotate on the ground...

[OldSchoolin86]

Ok, guys from my ATC200X service manual:


Primary Reduction: 3.33
Gear Ratio #1: 2.769
Gear Ratio #2: 1.941
Gear Ratio #3: 1.450
Gear Ratio #4: 1.130
Gear Ratio #5: 0.923

Final Reduction: 3.33




Now, I dont know, But I'm inclined to think that if you change the external sprockets (The main shaft, and the axle one) that you will be changing the # of times the wheels rotate on the ground...
YES!!! :D

[TimSr]

Now, I dont know, But I'm inclined to think that if you change the external sprockets (The main shaft, and the axle one) that you will be changing the # of times the wheels rotate on the ground...

I think we can all agree on that. Can we all agree that so will shifting gears?

[Billy Golightly]

Of course, but what happens when you get to 5th and theres no more to shift into?

[OldSchoolin86]

Of course, but what happens when you get to 5th and theres no more to shift into?That's the trade off for more torque; less top speed.

[Billy Golightly]

Right, But what I'm saying is once your in 5th and theres no more gears to shift into, you can't change the drive ratio again to counter act what was done with the sprockets. So, the final ratio (Once your in high gear) is changed, which is what I was trying to say :p

[AZ250R]

Of course, but what happens when you get to 5th and theres no more to shift into?
We're talk'n LATE Model 250Rs here, so... as I've just recently found out :eek:
Ya got 6th then your top'd out... :mad:
I had to change my sproket setup around to shoot hills @ the dunes, but could only do so after mess'n around with all the variables. Ya kinda gotta do it that way, trial & wreck... I mean error. :p
I'd go look @ what the similar rides R doing to make optimal runs then set up like that, almost every option has been tried @ some point so the right setup is out there somewhere... :naughty:

[AZ250R]

i wish i could stay quiet but...
this is wat i would use k i have seen several atc250R's-330Rs runnin this set up and they were smokein 370 banshees and all the way up to the 410 banshee, take and go to a 40 rear and a 12 front with 21inch 8 paddle haulers, u wont spin to bad and ahve the acceleration factor
I like this idea, & may have to try it sometime, but were they runn'n flat or up hill?


i run 13/39 with 21inch 8 paddle haulers
adam
Isn't this basicly "stock setup" with a bit smaller diameter tire, thus a TAD more bottom end / torque???
Its the same as I run & I think its dial'd in perfect for "all around dune'n"! :beer

[OldSchoolin86]

Right, But what I'm saying is once your in 5th and theres no more gears to shift into, you can't change the drive ratio again to counter act what was done with the sprockets. So, the final ratio (Once your in high gear) is changed, which is what I was trying to say :p
lol, I'm with ya 100%. That was my failed attemp to agree with you. ;)

[Billy Golightly]

lol, Sorry Oldschoolin! No more friendly fire :p

[Mr. Sandman]

1985 ATC 250R Trans Ratios
Primary Reduction - 2.652
Final Reducttion - 3.000
1st - 2.570
2nd - 2.062
3rd - 1.667
4th - 1.333
5th - 1.083
6th - 0.884

[TimSr]

Of course, but what happens when you get to 5th and theres no more to shift into?


That's the trade off for more torque; less top speed.



Changing sprockets is for when you need to operate outside the limitations of your gearbox




Son of a Gun, I think we agree on something!!!!!! I get the feeling we are all saying the same thing in a different language.

[OldSchoolin86]

Son of a Gun, I think we agree on something!!!!!! I get the feeling we are all saying the same thing in a different language.
Close, but are you seeing the light yet on acceleration?

[Studytime]

1985 ATC 250R Trans Ratios
Primary Reduction - 2.652
Final Reducttion - 3.000
1st - 2.570
2nd - 2.062
3rd - 1.667
4th - 1.333
5th - 1.083
6th - 0.884

That means 6th gear is literally overdriven. LOL, a trike with "overdrive".

Studytime

[a-camp]

Hey! What if he is hitting top speed before the finish??? I think bike is set up stock to do as best as possable in all kinds of riding . Until you modify with more power .So they might of gave a little on top speed to climb hills better. So If all he wants to do is race on level ground . I think its safe to say drop a tooth in the rear and see if the bike pulls it. Droping gear ratio numbers is adding complexity if you dont already know them. Two bikes can go even up to 60MPH neck and neck and one may move on to 70mph while the other stays at 60MPH corect ? Either someone can shift good or they cant. If they cant they will never win. But gears do make a differance.

[OldSchoolin86]

Two bikes can go even up to 60MPH neck and neck and one may move on to 70mph while the other stays at 60MPH corect ?
Only if the one that is still pulling up to 70mph has a better power to weight ratio. If you have 2 equal power to weight ratio machines and one is geared for 60mph and the other is geared for 70 mph the 60mph one will reach 60 before the 70mph one will. It simply has a better advantage.

[NOS_350X]

Changing sprockets is for when you need to operate outside the limitations of your gearbox.
I dissagree with you there, changing sprokets is to change the powerdilivery on your bike.

[a-camp]

Only if the one that is still pulling up to 70mph has a better power to weight ratio. If you have 2 equal power to weight ratio machines and one is geared for 60mph and the other is geared for 70 mph the 60mph one will reach 60 before the 70mph one will. It simply has a better advantage.
I agree.But it has to be geared lower or they would not be the same at 60MPH he would be faster all around . Anyways :I think since the stock sprockets are for all around riding and they get up to top speed long before you finish. You can drop a tooth.
You would really need a dyno too know , measure output though every gear to see what your losing per tooth .

[KASEY]

theres no way a stock 250r is going to run out of gears in 300',,,,

[Studytime]

I agree.But it has to be geared lower or they would not be the same at 60MPH he would be faster all around . Anyways :I think since the stock sprockets are for all around riding and they get up to top speed long before you finish. You can drop a tooth.
You would really need a dyno too know , measure output though every gear to see what your losing per tooth .


A chassis dyno does not care what gears you are using. Power is independent of mechanical gearing advantage. What do you mean by measure output through every gear to see what you're losing per tooth? Changing your torque multiplication ratio does not affect power, it simply multiplies torque more or less. You will not "loose" any thing. If you loose an amount of torque you gain more mph in each gear.

A dyno will not help in this case. Practice, a stopwatch, and a couple of sprockets would be way more valuable than a dyno.

Studytime

[Studytime]

What does your typical 250r motor spin to (rpm)?

Give me a few educated guesses of mph at the end of a 300' drag. Please provide some VALID answers as they may be used for computations.

Studytime

[OldSchoolin86]

What does your typical 250r motor spin to (rpm)?
http://www.fmfracing.com/dynocharts/honda/4trx250rsst.jpg

[TimSr]

If you have 2 equal power to weight ratio machines and one is geared for 60mph and the other is geared for 70 mph the 60mph one will reach 60 before the 70mph one will.


This is the part I totally disagree with UNLESS both machines normally do 1st gear starts, which is rare. If the guy who is geared for 70 starts in 2nd, and the guy who is geared lower starts in 3rd you may not see any difference at all, and it could even go the other way. By your own chart, which I agree with, the guy geared to 60 will begin losing horespower before he tops out.

[Studytime]

This is the part I totally disagree with UNLESS both machines normally do 1st gear starts, which is rare. If the guy who is geared for 70 starts in 2nd, and the guy who is geared lower starts in 3rd you may not see any difference at all, and it could even go the other way. By your own chart, which I agree with, the guy geared to 60 will begin losing horespower before he tops out.


Again, you are not comparing similar situations. Of course you're right. The assumption was that both riders would start in first. If the bike geared for 60 mph starts off in 3th gear and the 70mph bike starts off in first then, by your logic, of course, the bike geared higher (70) could win.

It was assumed both would start in first and that both riders would have the exact same skill level and that they'd have the same amount of traction.

Studytime

[OldSchoolin86]

This is the part I totally disagree with UNLESS both machines normally do 1st gear starts, which is rare. If the guy who is geared for 70 starts in 2nd, and the guy who is geared lower starts in 3rd you may not see any difference at all, and it could even go the other way. By your own chart, which I agree with, the guy geared to 60 will begin losing horespower before he tops out.
lmao, I give up.

[Studytime]

I still need to know what speed will be attained in this 300' drag.

I also need to know stock 250r gearing & which gear "stockers" race from in the sand. If it's second gear, why? For increased traction or what? As in, do you just sit there and spin in first.

Thanks. When I get this information, some interesting analysis may follow. I already see one good point that would give an advantage when drag racing.

Studytime

[Mr. Sandman]

IMO, a top speed in a 300' run would be about 50-55 mph +/-, but it depends on the rider and conditions.

Stock 250 R gearing is 13/39.

Hill shooting dunes usually requires a high revving 2nd gear launch which minimizes wheel spin and helps keep the front end down, but again, it depends on conditions, i.e., tires, wet or dry sand, etc.

[TimSr]

The assumption was that both riders would start in first. If the bike geared for 60 mph starts off in 3th gear and the 70mph bike starts off in first then, by your logic, of course, the bike geared higher (70) could win.

Why would you make that assumption? This thread is about a simple 300' drag. I dont know of any drag racing rules that require a driver to start in first and would assume neither rider would start in first. I know of no racers that start in first. I was advising the guy to try different gears before trying different sprockets. And Ill empphasize that I said the higher geared guy "might" win, not "would" win. Where you are in the power band when you take off is more critical than where you are in it when you hit the finish line.

The poor guy is probably sorry he ever asked the question, which was if gearing up or down will change his time on his 86 ATC250R in a 300" drag. He got different answers which basically were:

1. Not unless you are starting in low gear or running out of gears before the finish or need to start someplace in between gears.

2. Lowering gearing will improve acceleration throughout the gear range, so go as low as you can without running out of gears.

I guess he'll have to decide which theory holds true for himself.


In answer, what speed is typical in a 300' drag, somebody had a GPS at Trikefest, and I think their strip was 500' and if I remember right, the fastest speed reached was 62mph. Somebody who was there can correct me if Im wrong. I cant remember who gave me that info, maybe Bill the Finger or TriZ-Jim. You can make your own guess at 300" but as Kasey said, your typical ATC250R is not going to top out.

There are two reasons for not starting in first gear. The higher the gear, the less likely you are to wheelie. The other reason is that gear changes cost time, so you start in as high a gear as you can, but still keeping it in the powerband and not depending on the clutch to keep it from bogging on take off.

[OldSchoolin86]

You can make your own guess at 300" but as Kasey said, your typical ATC250R is not going to top out.
I can't help myself, this is getting funny. If your not going to top out in a 300' race then why wouldn't you change your gearing for better acceleration?

[Studytime]

IMO, a top speed in a 300' run would be about 50-55 mph +/-, but it depends on the rider and conditions.

Stock 250 R gearing is 13/39.

Hill shooting dunes usually requires a high revving 2nd gear launch which minimizes wheel spin and helps keep the front end down, but again, it depends on conditions, i.e., tires, wet or dry sand, etc.

So second gear is better than first for take-offs in sand. Would it help if second was a little lower or a little higher than it is with a 13/39 gear setup?

Speed, in most cases should be less than 60-ish mph.

Okay, to race a hare scramble requires skill. To drag race is different. It's more about preparation and knowlegde, yet some skill is still required. This leads me to another question. Does a good dunes racer have a problem with shifting? Can he or she maker his/her shifts consistant, quick, and accurate?

Thanks,
Studytime

[Studytime]

Oh, yeah! We're talking about varialbes here. Wet vs. dry sand etc. Not every 300' drag will be the same I'd venture to say. So, I guess this is worth taking note of too.

Studytime

[Mr. Sandman]

Drag racing on flat sand is totally different than hill shooting, which is basically a drag race up hill to the top of the dune. Hill shooting is usually a race up comp hill which is the tallest or steepest dune at the riding area. Where I ride, Dumont Dunes, comp hill is about 500' high from the base of the dunes.

Which gear to launch in depends on a lot of things, rider skill, the sand, how your bike is set up, tire size, etc. Typically, there is nasty section of whoops from the bottom to 1/4 of the way or so up the face of the dune. Picking the cleanest line to follow helps tremendously and whoever gets to the top first wins. The you turn around, go back down and do it all over again.

As for shifting, quick, accurate and clutchless while WOT is the key.

[a-camp]

What i was thinking on the dyno was if you go to high in your gears you will see a drop in rear wheel power in each gear. Some more than other.Just trying to show this is all more complex than a $20 steal sproket. Easy to drop a tooth and see if it works for your aplication.

[Studytime]

What i was thinking on the dyno was if you go to high in your gears you will see a drop in rear wheel power in each gear. Some more than other.Just trying to show this is all more complex than a $20 steal sproket. Easy to drop a tooth and see if it works for your aplication.


Negative. This is incorrect. Changing your gear ratio WILL NOT affect the power read by a dyno.

Studytime

[a-camp]

If you cant feel a loss of rear wheel output or RPM by gearing too tall on a Dyno you taught me.Im wrong..

[KASEY]

lol!!! studytime , all the preperation ,gearing ,shifting and,power can be all thrown out the window if you misread the sand,,,,, we race up a hill that is so steep you can't hardly walk or climb up it,,,, and if you come unprepared you will get smoked,,, one missed shift and its bye bye ,,,, thats what makes it so much fun,,, all it takes is a incorrectly adjusted clutch to hang up for .05 of a second when shifting and you usually end up eating sand,,, all these variables run through your head ,days of prep for a few seconds of pleasure . like MR. SANDMAN SAID you turn around and head for the start line again to see if you can correct the mistakes you made or find a better line . then by the end of the day HOPE you got to the top of the hill first a few times ,,,, gearing,,,, WHAT?????? :D :D :D :D :D

[2strokepwer]

i use a 12 tooth for the front and a 41 tooth for the rear on my 86 250r for 300 ft drag races on clay. :w00t:

[OldSchoolin86]

If you cant feel a loss of rear wheel output or RPM by gearing too tall on a Dyno you taught me.Im wrong..
What studytime is saying is that you can't change HP by gearing. It doesn't matter what gear you have shifted in or what set of sprockets you have, your HP will be the same.

HP is the relationship between known engine torque at specific rpm divided by Watt’s equivalent unit of one horsepower. Simplified, the equation is:

Hp = rpm x torque / 5,252

Conversely, to calculate torque the equation is:

Torque = 5,252 x hp / rpm

So as you shift up and loose torque in trade for speed, HP stays the same because it is a rating of both in relation to each other. HP is a measurement of work performed. As you shift the formula continues to balance.

[a-camp]

What studytime is saying is that you can't change HP by gearing. It doesn't matter what gear you have shifted in or what set of sprockets you have, your HP will be the same.

HP is the relationship between known engine torque at specific rpm divided by Watt’s equivalent unit of one horsepower. Simplified, the equation is:

Hp = rpm x torque / 5,252

Conversely, to calculate torque the equation is:

Torque = 5,252 x hp / rpm

So as you shift up and loose torque in trade for speed, HP stays the same because it is a rating of both in relation to each other. HP is a measurement of work performed. As you shift the formula continues to balance.
This is all true I know. If you put an 11tooth on the front and a 34 tooth on the back of a stock bike. It will not lose rear wheel hp or RPMs??? PLEASE just awnser the question.No more ratios.

[Studytime]

This is all true I know. If you put an 11tooth on the front and a 34 tooth on the back of a stock bike. It will not lose rear wheel hp or RPMs??? PLEASE just awnser the question.No more ratios.

You question is rather confusing, but a gear change of any kind WILL NOT, again, will not cause a decrease in RWHP. You may experience it taking longer to attain maximum engine speed, but this is not a 'decrease' in rwhp. The trade off is you're now going faster while accelerating slower.



Studytime

[a-camp]

What if it wont turn the wheels its so high? Are you still at 50HP? You wont get up the RPMs if your geared to high.This would not show ha?

[Billy Golightly]

I dont know anything, but I'm going to have to disagree. :p

A gear change will not change crankshaft horsepower, but I think it WILL change RWHP.

My reasoning is:

I have a 1hp engine with a 6 inch pulley on it. The adjoining pulley connecting by belt is also 6 inches in diameter. If I change the pulley on the motor to say a 2inch one, and the adjoining pulley to say, 10 inches, aren't I making more torque at the adjoining pulley then I was before?

If not, why do trucks that are being used for pulling heavy loads generaly geared lower then trucks that are not? Isn't extra torque needed to tow loads?

HP is only an equation consisting of torque, and RPM, correct? So, if your torque output is changed, how is the HP not also?

[a-camp]

[QUOTE=HondaATC]disagree. :p

A gear change will not change crankshaft horsepower, but I think it WILL change RWHP.

Thank you thats all I'm trying to say. I know its very complicated and I think shifting at peak RPMs is most important .
A smaller rear sprocket will make a stock bike faster (not quicker).Im not trying to prove it will win the race.Thats a lot of varibles However I entered my first dirt bike race 20 years ago this year And im saying its worth spending $20 bucks to find out in his case.

[KASEY]

dude your confusing torque with horsepower,,, if an engine puts out 30 hp on a dyno thats all it puts out at any gearing torque changes with gearing :D :D :D :D

[a-camp]

Rwhp?????....

[a-camp]

They mesure that wide open. I see what your saying .But if it cant turn the RPMs will it still have the HP ??

[KASEY]

a-camp slow down ,,,you posted this :

If you put an 11tooth on the front and a 34 tooth on the back of a stock bike.

11/34 is the same as 13/39 3.0 to 1 so you were thinking the wrong way,,,
gearing UP so high a bike won't pull it doesn't reduce horsepower ,,, it just means your geared to high,,,,

[a-camp]

a-camp slow down ,,,you posted this :


11/34 is the same as 13/39 3.0 to 1 so you were thinking the wrong way,,,
gearing UP so high a bike won't pull it doesn't reduce horsepower ,,, it just means your geared to high,,,,
Your right I see that now.I just cant except Gearing to high will not change the HP at the rear wheels . I think it will drop all the way through. Try one more time for me .

[Mr. Sandman]

Let's go back to the original question without all the analysis.


i have a 86 250r and was wondering what would get me a faster 300' drag time going up in teeth to get topend speed or going down it teeth for mor acceleration? what do you guys thing every thing on the bike is stock
The 250R has stock gearing of 13/39 with 20" tires. Changing the front sprocket to a larger size or the rear to a smaller size will cause the bike to rev and accelerate slower, but it will have a higher top end speed.

The opposite is true if you go smaller in the front or larger in the rear, which in turn will cause the bike to rev and accelerate quicker, but your top speed will be slower.

If the tire size changes to a smaller diameter than the stock 20" tires, to compensate and get back to the original/stock 3.0 gear ratio, you would have to use a bigger front sprocket or a smaller rear sprocket.

If you go with a taller tire than stock, you would do the opposite, go to a smaller countershaft or larger rear sprocket.

In the long run, it's all trial and error as riding in sand is totally different than hard pack dirt or even asphalt.

The easiest and most economical way to experiment and find out which is the right gearing setup for you is to pick up 12, 14 & 15 tooth sprockets & a stopwatch to play around with until you get the outcome your looking for.

Additionally, I don't really see how you can work transmission gear ratios into the equation since the normal weekend rider/racer is not going to attempt to change the gears, if there are even any different ones available to change, a pro racer might, but not the average guy or gal.

[KASEY]

ok one more time,, it might seem like you are loosing power when you gear to high,,, but the fact is the power you have will only pull so much gear,,, then it requires MORE power to pull it,,,, so it seems like you are losing power, all you are doing is moving to a point where it requires more than you have ,,,

[OldSchoolin86]

Rwhp?????....
YES! As almost everyone is saying, you can not change rwhp with gearing or shifting. You can only change torque.

[OldSchoolin86]

torque output is changed, how is the HP not also?
KASEY did a great job explaining this too.

To answer it again, when you change your torque by gearing you change your speed too. Every gear change you do will balance that torque/speed ratio out again. When you go up in torque your speed goes down. When you go down in torque your speed goes up. If you plug in some numbers in the formula on the previous page you will see that HP never changes by gearing. KASEY did a great job explaining this too.

[TimSr]

I can't help myself, this is getting funny. If your not going to top out in a 300' race then why wouldn't you change your gearing for better acceleration?

I guess we go back to my very first post. Changing sprockets to gear down will have no effect on acceleration unless you are trying to operate outside the limits of the gearbox, which means starting in first gear, which will be below where first gear is now, but you dont notice because you arent using first gear for a holeshot, and after you gear down more, your probably not using 2nd gear either. After you change sprocket gearing, once you are moving and ready to shift gears, you may be in a different gear than you were before, but you are still shifting at the same RPMs, and the same RPM range from the to bottom of each gear, so you are not accelerating any faster.
Acceleration speed is engine power. As long as you are operating in the powerband, you are getting your maximum acceleration speed. Gearing cant add power to that. We use gearing to keep us in the power band to prevent LOSS of that power. There is no way to can add engine power with gearing. As long as you are max power, running in the powerband, which is what acceleration speed is, you cannot gain accleration speed by gearing downward, and if it will stay in the powerband, you cannot lose acceleration speed by gearing up. Sprockets cant add engine power. They can only prevent a load on it. If your 250R runs in the powerband, youre not feeling much of a load. What gear does it accelerate fastest in on flat ground? You probably cant tell if you are shifting at the same rpm each shift. Its probably not 1st gear. It peaks and HP drops too quickly.

[Studytime]

:rolleyes: Adding what you think from poorly educated reasoning will not get this thread anywhere.

I think some of us need to open our minds.

Studytime

[Mr. Sandman]

Tim is correct in saying you won't accelerate any quicker with a gear change. I mis-spoke when I said you'd accelerate quicker. I should have said you will go through the gears quicker, reach redline quicker and wish you had another gear.

[Studytime]

Tim is correct in saying you won't accelerate any quicker with a gear change. I mis-spoke when I said you'd accelerate quicker. I should have said you will go through the gears quicker, reach redline quicker and wish you had another gear.

How can you get to the end of your gears quicker and reach max speed quicker without accelerating quicker?

No, Tim is INCORRECT; you WILL accelerate faster with a gear change. You are supplying more torque to your rear wheels. How could you do this and think you will not accelerate any faster?

Studytime

[Studytime]

Tim, I don't mean to be rude, but you are claiming that gearing makes zero change in acceleration.

Do you find you accelerate faster in 2nd gear or 5th gear? I'd bet second and that's because of "mechanical advantage". Yes, it's gearing. I think you're a little off on this one.

Studytime

[OldSchoolin86]

I guess we go back to my very first post. Changing sprockets to gear down will have no effect on acceleration unless you are trying to operate outside the limits of the gearbox, which means starting in first gear, which will be below where first gear is now, but you dont notice because you arent using first gear for a holeshot, and after you gear down more, your probably not using 2nd gear either. After you change sprocket gearing, once you are moving and ready to shift gears, you may be in a different gear than you were before, but you are still shifting at the same RPMs, and the same RPM range from the to bottom of each gear, so you are not accelerating any faster.TimSr, yes you are changing your acceleration. I don't know how to explain it so you will see that. I know gearing doesn't change hp but it does change torque. When you set up your sprockets for more torque, you change every gear you are in. Every gear is shorter and stronger. Put a machine in low range and you'll see that.

Acceleration speed is engine power. As long as you are operating in the powerband, you are getting your maximum acceleration speed. Gearing cant add power to that. We use gearing to keep us in the power band to prevent LOSS of that power. There is no way to can add engine power with gearing. As long as you are max power, running in the powerband, which is what acceleration speed is, you cannot gain accleration speed by gearing downward, and if it will stay in the powerband, you cannot lose acceleration speed by gearing up. .Yes you can. If your geared to the moon to go 100mph compaired to 60mph you will not pull the same in your powerband. Your 60mph gearing will pull harder and faster.

Sprockets cant add engine power.Correct but you can add rear wheel torque.

They can only prevent a load on it. If your 250R runs in the powerband, youre not feeling much of a load. What gear does it accelerate fastest in on flat ground? You probably cant tell if you are shifting at the same rpm each shift. Its probably not 1st gear. It peaks and HP drops too quickly.What gear do you run out faster, 1st or 6th? There's your answer. We both know 4x4 in low range won't win many drag races but if your geared to high you won't be winning to many holeshots either(equal skill riders). A 250R can pull some good gearing but that doesn't rule out the rules of acceleration. A 250R may not need a lower ratio in a 300ft drag but if your geared so your riding out the rest of your powerband in your final gear as you cross the finish line then you are geared for optimal acceleration. If you gear it so your not even shifting into your final gear at the finish line you are seriously cheating yourself.

[TimSr]

Your gears run out at the same speed until you start asking more of the motor than it can deliver. By 5th and 6th gear you do lose acceleration speed because of the load on the motor. Try it going downhill, and youll see different results. In 2nd 3rd and 4th youre not going to see much of that.

Let me ask one of those math type story problems.

Lets say you have two exact bikes with 6 speed trannys. All 6 gears are spaced evenly apart. Lets say Bike A has stock gearing and Bike B is geared down with the sprockets to where each gear is exactly one gear lower than stock. 2nd, 3rd, 4th, 5th and 6th gear on Bike B turn the axle the same speed as 1st, 2nd, 3rd, 4th, and 5th gear on bike A. They run a short drag. Bike A starts in 2nd gear and and ends topped out in 5th gear. Bike B starts in 3rd gear, which, because of the sprockets, turns the wheel the same out as 2nd on Bike A.

Who takes off faster?
Who accelerates faster?
What gear did bike B end up in?
Who finished first?

Since they only ran in the overlapping ranges of each gearbox, my theory is that they both tied in each question, and bike B ended up topped out in 6th. Bike B was geared a fuill gear lower. Lower gearing did not help bike B one bit, because lower or higher gearing only shifts your range up or down, and has no affect within the range. You may be in a different numbered gear, but it wont affect the rate you shift through them. You can lower your starting point, or you can raise your ending point, but it has no affect on the rate of acceleration between those two points.

[RacerRichie]

Acceleration speed is engine power. As long as you are operating in the powerband, you are getting your maximum acceleration speed. Gearing cant add power to that. We use gearing to keep us in the power band to prevent LOSS of that power.

YES THIS IS IT.
I second this very true statement. :beer
This thread is over. :rolleyes:

[Studytime]

YES THIS IS IT.
I second this very true statement. beer
This thread is over. :rolleyes:


NO, again this is incorrect. Gearing will also make you accelerate faster.

I just don't see how you don't understand. You, at least, recognize there is a larger "load" on the motor in sixth. This is because sixth gear is geared higher than first/second. The load is a result of less aggressive gearing.

You can't add something extra to prove your point, i.e. "going downhill". I coud say you spun a bearing before sixth so first/second is faster acceleration. Just how my statement does not help this thread to progress; neither does saying you're now going down hill. WHEN you are goign downhill it requires less hp to get "up to speed" because gravity also help you accelerate thanks to good ole potential energy.

Studytime

[Studytime]

Let me try to ascertain my point with two relevant examples;

case #1
Why in the world would you put 4.10 gears in your trans am, KNOWING that you will not cruise at a higher engine speed for any given speed? You would do this because the trade off is increased acceleration. If you mentioned that swapping a race car's 4.88:1 gears for a set of 3.08 gears would make no effect on his quarter mile elapsed time, you be laughed out of the stands.

case #2
Have you ever used a "cheater pipe"? Such a tool allows it's user to apply more torque to remove a stubburn nut/bolt. The reason one uses this is because of the increased torque delivery; however, after his or her bolt/nut has become free such user does not use this cheater pipe. Tim, I'm sure you have done this. The extension on your socket will allow you to provide more torque and get a rusted bolt out faster than not using a cheater pipe. You're pushing along the tanget line of a LARGER DIAMTER circle this way, and although you're pushing easier you are covering more ground and it will not be easy to turn the bolt fast. When you take the pipe off, now your hands trace a smaller diamter circle and you're pushing around a shorter circumference. This way will allow you to turn the bolt/nut assembly faster.

Hopefully you will see the analogy to using a longer wrench or cheater pipe.

Good luck on your quest for knowledge.

Studytime

[Studytime]

Your gears run out at the same speed until you start asking more of the motor than it can deliver. By 5th and 6th gear you do lose acceleration speed because of the load on the motor. Try it going downhill, and youll see different results. In 2nd 3rd and 4th youre not going to see much of that.

Let me ask one of those math type story problems.

Lets say you have two exact bikes with 6 speed trannys. All 6 gears are spaced evenly apart. Lets say Bike A has stock gearing and Bike B is geared down with the sprockets to where each gear is exactly one gear lower than stock. 2nd, 3rd, 4th, 5th and 6th gear on Bike B turn the axle the same speed as 1st, 2nd, 3rd, 4th, and 5th gear on bike A. They run a short drag. Bike A starts in 2nd gear and and ends topped out in 5th gear. Bike B starts in 3rd gear, which, because of the sprockets, turns the wheel the same out as 2nd on Bike A.

Who takes off faster?
Who accelerates faster?
What gear did bike B end up in?
Who finished first?

Since they only ran in the overlapping ranges of each gearbox, my theory is that they both tied in each question, and bike B ended up topped out in 6th. Bike B was geared a fuill gear lower. Lower gearing did not help bike B one bit, because lower or higher gearing only shifts your range up or down, and has no affect within the range. You may be in a different numbered gear, but it wont affect the rate you shift through them. You can lower your starting point, or you can raise your ending point, but it has no affect on the rate of acceleration between those two points.

Who takes off faster?/Who accelerates faster?
Well, you simplified this by saying there was the same gap between gears for both bikes. Based on this assumption, then neither bike accelerates faster.

B ends up in 6th gear

They would, hypothetically, finish at the same time.

In the rear world with the two bikes geared as you are saying; the bike using 2-6 would outperform the bike using 1-5. That is the bike geared down would win. It would accelerate faster because using gears 2-6 it applies more torque after shifts than the 1-5 trike. This is because there is less of a gap after the tranny shifts.

Studytime

[a-camp]

[QUOTE=TimSr]Your gears run out at the same speed until you start asking more of the motor than it can deliver. By 5th and 6th gear you do lose acceleration speed because of the load on the motor.
So this is loss of torque not wheel power ??? Or both

I have seen some great points in this thread .I disagree I think were going far on this tread and think were close to a break through.If we can just keep are egos under control (my own included) we can push through.

When you add more power Hp to a bike are you saying gears wont give you more top end.The HP could make up for the taller gears 0-60 against a stock bike and move on to 70 Or no.??

[a-camp]

I think my bike power is beyond the stock gearing I just moved to a 38 in the rear. If my bike will turn it will i not get more speed in every gear?? On level ground lets keep it simple.

[Studytime]

[QUOTE=TimSr]Your gears run out at the same speed until you start asking more of the motor than it can deliver. By 5th and 6th gear you do lose acceleration speed because of the load on the motor.
So this is loss of torque not wheel power ??? Or both



I believe this has been stated numerous times already that a sprocket change WILL NOT affect rear wheel hp. It can change how much torque is applied however.

This has been stated many times already.

I don't see this thread going anywhere.

Studytime

[Billy Golightly]

I think I understand that part now, because even though you are increasing the torque output by a gearing change, your also changing the amount of rotations, the other part of the equation to make HP.

[a-camp]

Then dont come back to it.Sound like we are all just to slow for you.May need to find smarter people to talk with if you dont have the patiance to deal.

[Studytime]

Then dont come back to it.Sound like we are all just to slow for you.May need to find smarter people to talk with if you dont have the patiance to deal.

I'm guessing this was directed at me. "Dont have the patiance to deal", well, the fact that I am still posting disproves that I am lacking on patience. I'm just trying to give this thread some direction.


Sound like we are all just to slow for you.

You're tyring to single me out against the forum when I'm just saying that something is incorrect. Is it my fault that's it's wrong? No. I did decide to let it be known that some postings were wrong however. An author by the name of Paul once said, "have I become your enemy by telling you the truth".

If you have a personal issue against me- take it up with me out of this thread in a PM.

Studytime

[Studytime]

I think I understand that part now, because even though you are increasing the torque output by a gearing change, your also changing the amount of rotations, the other part of the equation to make HP.


;) Progression. Yes, I do believe you are understanding it now.

Studytime

[KASEY]

GREAT THREAD!!!!i like long drawn out things like this that don't get out of control. there is alot of good information in this one ,,,, heated debates are good,,, i like all the technical explinaitions ,, cause i use the seat of the pants method of going faster,,,, i listen to the motor ,,feel how its pulling,, study the start line ,, watch the lines on the track,,,,do a few plug checks to see how its preforming and try to preform flawless shifts when out there ,,,,, and do all this for a couple of seconds of fun!!!! we must be nuts! :D :D :D

[a-camp]

I think my bike power is beyond the stock gearing I just moved to a 38 in the rear. If my bike will turn it will i not get more speed in every gear?? On level ground lets keep it simple.


Ok lets get back to work. Will you guys input on this?

[OldSchoolin86]

GREAT THREAD!!!!i like long drawn out things like this that don't get out of control. there is alot of good information in this one ,,,, heated debates are good,,, i like all the technical explinaitions ,, cause i use the seat of the pants method of going faster,,,, i listen to the motor ,,feel how its pulling,, study the start line ,, watch the lines on the track,,,,do a few plug checks to see how its preforming and try to preform flawless shifts when out there ,,,,, and do all this for a couple of seconds of fun!!!! we must be nuts! :D :D :D
That's the spirit!!! :beer

[NOS_350X]

Ok lets get back to work. Will you guys input on this?
Ok, then the answer is yes you will. Every gear will give you a little bit mph gain, and in the end you will have a faster overall speed, it will just take you longer to get to the top speed of your bike.

[KASEY]

OK HERE YOU GO,,,, 13/39 to mph (http://home.earthlink.net/~gellett/250r.htm)

13/38 to mph (http://home.earthlink.net/~gellett/250r.htm)

[TimSr]

LOL!! Stick a fork in me, Im done! Im geared a full 1 to 1/2 full gears lower than stock because I like to crawl up steep rocky hills and it works for me, and hasnt affected my MX lap times in either direction. I havent timed drag times, but if there is a difference, I sure dont notice it.

Im with Kasey and OS. Its nice to have a good spirited debate of opposing opinions without it getting abusive and disrespectful.

Here's a question to ponder. My TriZ does better MX lap times with a 5 speed bottom end than with a 6 speed bottom end. I also got better holeshots to the first corner. I did 2nd gear starts with both bottom ends, and had them geared to where they were both in pretty much the same gearing at 2nd gear. Anybody have any theories?

[KASEY]

yep ,,, if you have the power to pull a wider ratio ,,, it means less shifting more time on the power ,some places on the track you can just stay in one gear rather than have to shift which means ,,, better lap times.... thats why i went to a hrc wide ratio kit in my 500,,,, it has the power and in the dunes you need lotsa gear :D :D :D

[QuAd SlAyEr]

My question is this. If you lower the teeth on your front sprocket to get a quicker acceleration time, Then why would you want to start out in 2nd? Your wasting a whole gear by doing this. If you think that changing sprockets will not affect acceleration time then I suggest you ask someone in auto racing why one of the first mods is to go to a lower gear ratio? The reason being is it gets the motor to its power band faster and keeps it there. The trade off is the faster the acceleration the less top speed you will have and vise versa.

[a-camp]

Kasey thanks for the cool link.Will get back to this after work.Agree with everything said about WR so far.

[Wickedfinger]

... let me just ask this question ......... (some may actually wonder why I havn't - chimed in until now). I had an 1984 ATC200S, DG pipe, 22" rear tires - I changed out the front sprocket from an aftermarket 13tooth back to the stock 11tooth because I wanted more tractable power for the woods. After that change, the trike felt like it accellerated faster but topped out quicker and at a lower speed. No, I didn't have a speedometer or GPS on the bike - but I did do the stopwatch thing between telephone poles and ran it next to my buddies truck - and it was quicker in elapsed time and lower in top speed (down from @56 to @49-50 - I don't remember the accelleration numbers) ... why?.

[KASEY]

WELL ,,,, you just answered your own question,,,, smaller countershaft sprocket lower speed ,,,,more torque,,,,

[OldSchoolin86]

WELL ,,,, you just answered your own question,,,, smaller countershaft sprocket lower speed ,,,,more torque,,,,
Yup, more torque = faster acceleration = less top speed.

[Wickedfinger]

... thats my point ...... thats why I'm having trouble understanding this whole argument - am I missing something here?.

[TimSr]

My question is this. If you lower the teeth on your front sprocket to get a quicker acceleration time, Then why would you want to start out in 2nd? Your wasting a whole gear by doing this.

Read Kasey's post above yours. Same reason.

[TimSr]

... thats my point ...... thats why I'm having trouble understanding this whole argument - am I missing something here?.

Ive worked extensively with CVT trannys, and they give you a real good insight as to what affect sprockets have from bottom to top. With your being a Polaris guy, Im curious if you have any findings about sprockets affecting acceleration midway through your speed range of a CVT tranny.

[OldSchoolin86]

... thats my point ...... thats why I'm having trouble understanding this whole argument - am I missing something here?.
I don't think your missing anything here. Some just believe that you can't help acceleration with proper gearing.

[Wickedfinger]

Tim, believe me, I was genuine when I said
am I missing something here?. I was just trying to keep an open mind to the now seemingly flawed methodology I believe in.

Its true, I have said before that sprocket changes don't matter a whole lot when dealing with a CVT, but that was in relation to proper secondary clutching, not final drive. They just dont operate the same way as traditional geared transmission, they work off of a transfer case.

[Studytime]

My question is this. If you lower the teeth on your front sprocket to get a quicker acceleration time, Then why would you want to start out in 2nd? Your wasting a whole gear by doing this. If you think that changing sprockets will not affect acceleration time then I suggest you ask someone in auto racing why one of the first mods is to go to a lower gear ratio? The reason being is it gets the motor to its power band faster and keeps it there. The trade off is the faster the acceleration the less top speed you will have and vise versa.


Ding! Ding! Ding! Ding! You got it.

Studytime