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View Full Version : 85 250R Tuniing Help



daBIGKAHUNA
10-29-2011, 03:50 PM
Need some help from the 2 stroke bruthas on here. I recently fired up my 85 250R build. It started on the second kick and runs great at idle. The issue is when you accelerate - it starts off ok but when you get to the meat of the gear it starts to "sputter" or cutout/miss. If you stay on it - it will get through this stage and haul ass like it should. It runs great on top and puts around fine on bottom but when you gas it - it cuts out.

Now - the carb is I believe the stock 85 carb. I got the carb and thumb throttle all assembled and installed it just as it was. I have never cracked open the carb yet. I pulled the plug today to take a look after I road it for about 15 minutes and it looks blackish and moist as if its running rich- see blurry pic below for an idea.

http://i715.photobucket.com/albums/ww154/ORIGINALBIGKAHUNA/250r/MINE/TUNE/100_0457.jpg

What would be my next step? Air srew adjustment? If its running ok on top I assume the main jet is fine?

I am running Maxima K2 at 50:1 per a local guys suggestion. I have alot of oil build up at the cylinder head where the Exhaust connects - is this due to running too rich or the exhaust not being properly sealed? Here is a pic:

http://i715.photobucket.com/albums/ww154/ORIGINALBIGKAHUNA/250r/MINE/TUNE/100_0460.jpg

Any help is greatly appreciated. While not exactly a beginner - I am not 2 stroke tuner....thanks for your help!

Thanks to any and all that help!

falloutboy
10-30-2011, 03:39 AM
2 stroke oil is a touchy subject around here it seems, but 20:1 is pretty rich nowadays. I wouldn't go any richer than 32:1.

Chazz of Blades
10-30-2011, 04:10 AM
I've always, and always will, run all my smokers at 32:1. It's what I personally have found to be my favorite mixture ratio, but to each their own.

And beware taking advice from 'A Buddy' without research.

whyzee
10-30-2011, 05:54 AM
32:1 is fine also. But if your R is tuned perfectly it will run its best and last the longest at 20:1. It will also smoke very little and produce absolutely no pipe spooge. I run 20:1 always , with no spooge .
check your main jet the 85 likes a 142. But if you have any mods you will need to go up on your main.
I have a feeling your needle position and your main jet are off. Also check your aircrew. 1 1/2 turns back out from full in to start.
if you think your R is fast now...just wait till she is tuned perfectly

daBIGKAHUNA
10-30-2011, 08:45 PM
32:1 is fine also. But if your R is tuned perfectly it will run its best and last the longest at 20:1. It will also smoke very little and produce absolutely no pipe spooge. I run 20:1 always , with no spooge .
check your main jet the 85 likes a 142. But if you have any mods you will need to go up on your main.
I have a feeling your needle position and your main jet are off. Also check your aircrew. 1 1/2 turns back out from full in to start.
if you think your R is fast now...just wait till she is tuned perfectly

Thanks for the advice. I plan to make the adjustments sometimes this week. I'll post my results. I am assuming pipe spooge is what I have in this picture?

http://i715.photobucket.com/albums/ww154/ORIGINALBIGKAHUNA/250r/MINE/TUNE/100_0460.jpg

Are you saying that by adding more oil to the mix (20:1 vs. 50:1) that I will have less/no oil at the exhaust port? Is the mixture my problem for the above situation? Thanks to all ofr you help.

KASEY
10-30-2011, 09:21 PM
the reason for pipe spooge is not riding it hard enough to build some heat in the pipe,, if you do the oil situation will fix itself!!

RIDE-RED 250r
10-30-2011, 10:27 PM
Looks like you also may have a stock exhaust flange (that's likely worn out). Do your self a favor and get a new billet, double o-ring exhaust flange. It will greatly reduce exhaust spooge. You will always have a certain amount of exhaust spooge with a pinger, but like Kasey said, ride it the way it was meant to be ridden and it will run cleaner.

This is the one I have... works great. http://www.eddie-sanders-racing.com/product_p/billet%20exhaust%20flange.htm

3Razors
10-30-2011, 10:42 PM
Factory 250R jetting likes 20:1 oil mixture, 32:1 will work ok though, but with 50:1 you will have more spooge and possibly fouled plugs with the factory jetting. This is with castor or syn blended oils though. However with a full synthetic oil like K2 a 20:1 oil mixture is very hard for the oil to burn off. I would run 40:1 with K2 and lean out the jetting slightly.

KASEY
10-30-2011, 10:54 PM
on another note,, get the correct flanged washers for your rad shrouds before they start cracking,,, the lower needs to be able to move to prevent cracking,,,, thats why the oval hole.

daBIGKAHUNA
10-31-2011, 06:03 PM
32:1 is fine also. But if your R is tuned perfectly it will run its best and last the longest at 20:1. It will also smoke very little and produce absolutely no pipe spooge. I run 20:1 always , with no spooge .
check your main jet the 85 likes a 142. But if you have any mods you will need to go up on your main.
I have a feeling your needle position and your main jet are off. Also check your aircrew. 1 1/2 turns back out from full in to start.
if you think your R is fast now...just wait till she is tuned perfectly

Had a little bit of time this afternoon and adjusted the clip position on the needle to 3rd from the top as suggested - it made a positive differnce. I still have a little sputter but not nearly as much. It hits the sputter stage and comes out of it much quicker.

When I get time I will work with the air screw and see if I can adjust the rest of the sputter out of it. The main Jet is a 130 - I have a K&N and FMF pipe and silencer....should I try the 142 as suggested or go up in smaller increments?

On the pipe spooge - thanks to all for your advice. The rear brakes are not there yet so riding is just been short test runs and around the yard. Once the brakes are there and the tuning is corrected I will be able to put the bike to full use.

Kasey - thanks for the advice on the shroud washers - just need to find some and install them.

falloutboy
11-01-2011, 12:56 AM
Had a little bit of time this afternoon and adjusted the clip position on the needle to 3rd from the top as suggested - it made a positive differnce. I still have a little sputter but not nearly as much. It hits the sputter stage and comes out of it much quicker.

When I get time I will work with the air screw and see if I can adjust the rest of the sputter out of it. The main Jet is a 130 - I have a K&N and FMF pipe and silencer....should I try the 142 as suggested or go up in smaller increments?

If you seem to be running good at WOT, I would leave the main jet alone. Same for the air screw. If it runs good at idle-1/4 throttle, I wouldn't mess with the air screw.

I would try moving the clip on the needle another notch and see what it does...

daBIGKAHUNA
11-01-2011, 02:05 AM
If you seem to be running good at WOT, I would leave the main jet alone. Same for the air screw. If it runs good at idle-1/4 throttle, I wouldn't mess with the air screw.

I would try moving the clip on the needle another notch and see what it does...

Thats just it - the sputter stage is right about 1/4 throttle. Does a 130 main jet sound right for my set up? If it calls for a 142 in stock form I was thinking that my setup would at least call for the a 142 with the after market pipe/silencer and K&N filter. Thanks for the help!

whyzee
11-01-2011, 09:45 AM
Definitly go with the 142 main. You are waaay to lean at 130. As far as the sputtering at 0-1/4 throttle, that will be in the air screw. Don't be afraid to drop that clip 1 more notch. But first go to the 142 main!

falloutboy
11-02-2011, 01:48 AM
It's really tough to say. What is your elevation approximately? I think the 142 is meant for around sea level...

From your picture the plug doesn't appear to be lean, but it could be rich at 1/4 throttle and lean on top end. Its tough to say until you do a WOT plug chop. Just remember, gray and ashy is lean.

It's easy enough to adjust you air screw out a little to see if it helps. If it gets worse tighten it a tiny bit. tightening the screw is richer and loosening it is leaner.

the carb jetting 101 page got me through re-jetting my bike and might be able to explain a little better than I can

Carb-Jetting-101-Terms-Tips-and-Jetting-Theory (http://www.3wheelerworld.com/showthread.php/55086-Carb-Jetting-101-Terms-Tips-and-Jetting-Theory)

daBIGKAHUNA
11-02-2011, 12:49 PM
It's really tough to say. What is your elevation approximately? I think the 142 is meant for around sea level...

From your picture the plug doesn't appear to be lean, but it could be rich at 1/4 throttle and lean on top end. Its tough to say until you do a WOT plug chop. Just remember, gray and ashy is lean.

It's easy enough to adjust you air screw out a little to see if it helps. If it gets worse tighten it a tiny bit. tightening the screw is richer and loosening it is leaner.

the carb jetting 101 page got me through re-jetting my bike and might be able to explain a little better than I can

Carb-Jetting-101-Terms-Tips-and-Jetting-Theory (http://www.3wheelerworld.com/showthread.php/55086-Carb-Jetting-101-Terms-Tips-and-Jetting-Theory)

FWIW - I am in Monroe La. and am about 120ft above sea level.

**EDIT**

After giving that jetting post a quick run through I think it would be best for me start over from scatch with the factory specs. Per the maunal at my altitude/temps it list a 142 main, needle at the second clip position and air screw 2 turns out. There is literally NO listing for a 130 main jet.

daBIGKAHUNA
11-03-2011, 12:54 AM
I pulled apart a spare carb I have laying around and it had a 145 main jet in it. I am going to try it out as that is what the FMF site suggests for this motor (http://ridersupport.fmfracing.com/JettingCenter). Will post my results when I ger around to getting it done. Thanks to all that have contributed.

falloutboy
11-03-2011, 01:20 AM
Good idea on going back to square 1. 130 does seem kind of small, esp. with a pipe and whatnot

Good luck!

daBIGKAHUNA
11-04-2011, 12:21 AM
Good idea on going back to square 1. 130 does seem kind of small, esp. with a pipe and whatnot

Good luck!

I plugged in the 145 today and set the needle in the 2 slot and and adjust the air screw out 1.5 turns.....ugghhhhh sputter from hell worse than before. I put the needle back in the 3 slot to start with - any other suggestions?

bradshea
11-04-2011, 12:57 AM
Are you running genuine keihin jets? I have used others with bad results. Also make sure your air filter is clean

Mosh
11-04-2011, 12:49 PM
My friend, I am going to say you are running into the "dreaded 85 carb issue" on your machine.
After playing with quite a few 85 round slides myself, I have only succesfully been able to get 2 of them tuned somewhat correct and seen 1 other run fairly well besides mine.
They had a design flaw in that carb in which the fuel would wick up past the main and pilot jets too much at mid throttle positions and cause them to run rich. You can tune it out, but usually in my experience, you have to jet them back so lean to get them to run somewhat correctly it is scarey, and they still will load up and foul plugs if you dont keep them blown out.
You could repeatedly kick yourself in the pants trying to dial it in, and still have a sub par carb on your bike. they just never did perform well compared to the PJ series carbs on the later years.
IMO, I would round up a good 86 ATC model carb, or even one off the TRX 250R that you know for certain ran good, and go with that set-up. You will have to update your cable as well with the later model carbs.

I am not saying yours is bad for sure, but after reading this thread and seeing it responds to leaning it out more and more, that is my assesment over a key board.
I dont even waist my time with those 85 carbs anymore.

whyzee
11-04-2011, 03:53 PM
How dirty is your air filter? There should be no reason for that bike to be sputtering. Try the 142 main , check the air filter, vent tube on the gas cap . Let me know

daBIGKAHUNA
11-04-2011, 07:58 PM
My friend, I am going to say you are running into the "dreaded 85 carb issue" on your machine.
After playing with quite a few 85 round slides myself, I have only succesfully been able to get 2 of them tuned somewhat correct and seen 1 other run fairly well besides mine.
They had a design flaw in that carb in which the fuel would wick up past the main and pilot jets too much at mid throttle positions and cause them to run rich. You can tune it out, but usually in my experience, you have to jet them back so lean to get them to run somewhat correctly it is scarey, and they still will load up and foul plugs if you dont keep them blown out.
You could repeatedly kick yourself in the pants trying to dial it in, and still have a sub par carb on your bike. they just never did perform well compared to the PJ series carbs on the later years.
IMO, I would round up a good 86 ATC model carb, or even one off the TRX 250R that you know for certain ran good, and go with that set-up. You will have to update your cable as well with the later model carbs.

I am not saying yours is bad for sure, but after reading this thread and seeing it responds to leaning it out more and more, that is my assesment over a key board.
I dont even waist my time with those 85 carbs anymore.

Interesting - that would definitely explain the 130 main jet.

daBIGKAHUNA
11-04-2011, 08:00 PM
How dirty is your air filter? There should be no reason for that bike to be sputtering. Try the 142 main , check the air filter, vent tube on the gas cap . Let me know

Filter is a brand new K&N. The vent tube on the gas cap is as well....

riverbottem
11-04-2011, 09:13 PM
Do not waste your time with the stock carb, I had the same problem with my 85' I absolutely could not get rid of the 1/4-1/2 throttle sputter, Spent $200 on a 35mm air striker quad vent...... Came with a 160 main and it ran good, dropped to a 148 main and it now runs perfect, smooth ass powerband with no sputter. DG pipe, K&N air filter @ 32:1 otherwise stock.

falloutboy
11-05-2011, 01:19 AM
Interesting point Mosh brought up. I've got the stock 85 carb too. Mine is set pretty lean on the slide needle- top notch as a matter of fact. Every once in a while it has a bit of a sputter. Oh, yeah, it won't stop pouring out the overflow, but that's a whole new thread :D
Eventually I'll put a PJ or PWK on it.

If your reaching the point of getting ready to the the P(OS)E --yeah, you see what I did there <<< :cool: -- out the window, like I am, as a last ditch effort, try moving the clip to the top notch and start out with your 145 main jet in. In theory it should take a bigger one than that but all bikes are different I guess...

I have a hunch, like Mosh was saying, you're going to have to lean it way back on the mid range in order for it to clean out.

daBIGKAHUNA
11-05-2011, 01:45 AM
The best its ran is with the 130, needle in the 3 slot and screw 2 turns out. I am tempted to just go back to that but I should probably work with the 145 first. If I had the money I would just buy the new carb but that aint gonna be happening for a while.

falloutboy
11-05-2011, 02:13 AM
Yeah, I hear you there. I was just looking up PJ's and PWK's. $175-250 for what I could find...

I found this in the service manual. If these carbs tend to run rich, like Mosh says, you would have to go leaner on the needle jet to compensate where you're having the issue.
http://img853.imageshack.us/img853/7867/carbs.jpg

My thinking is if you lean out your mid throttle by raising the needle clip (lowering the needle= less fuel) since this seems to be where the issue is. Leave the bigger jet in for now so you aren't too lean at WOT. Once that slide is drawn 75-100% open then you'll know if the main is too big or maybe even too small.

Mosh
11-05-2011, 10:55 AM
Most cycle salvage yards and ebay will sell PJ 34's and PJ 36's off Cr dirtbikes for 60-75 bucks. Ebay has them also around that price range.

whyzee
11-05-2011, 11:20 AM
The best its ran is with the 130, needle in the 3 slot and screw 2 turns out. I am tempted to just go back to that but I should probably work with the 145 first. If I had the money I would just buy the new carb but that aint gonna be happening for a while.

Try the needle clip on the very top of the needle with a 142 main jet before you settle on the way it is running. I know its a pain to keep doing but well worth the effort.

3Razors
11-05-2011, 07:29 PM
Are you 100% sure you have the stock 85R carb? Your first post said "you think so", post up a pic if there is any doubt