Another Tri-z to be powervalved!!!

[TRI Z Racer]

Well, i couldnt resist any longer, i had to tell someone the good news. I just found a guy in my hometown that threw a chain through his left side case on one of his dirtbikes... it just so happens to be a 85 yz250. He told me he was gonna part it out because he was sick of spending money on it. He had just rebuilt the motor not 1 hour before. he never tightened the chain and then blammo. Ii wasnt about to try to talk him out parting it out. So me... being the super bargain shopper :D i am, decided to make an offer on the engine, $125 for complete motor and the carb.
He pulled the cylinder and i looked at it, all smooth, can still see hone marks, and the piston doesnt have a spec of carbon buildup on it yet! Needless to say im psyked!!!

My questions to all those who have done it already. I only have a DG pipe, is this pipe gonna work out ok? Will the difference still be very noticable? I did some searching and i found that somebody said they did it and didnt see much of a gain. Along with that post i saw somebody said they tried a 38mm carb and it ws SLOW, switched to a 40 and it made a huge dif. I also saw a post that said they had a huge gain, very noticable with the 38mm. I have a 38mm carb now.

Whats the real deal behind all this?

Can anyone shed some light on this for me?


IM SO EXCITED :w00t:

[diggerzmound]

I got all excited about doing this too, in fact i got it done. The hardest part of the whole ordeal isattaching the carb to the engine. The YZ cylinder points the intake off the the left, and the Tri-Z is centered..

http://www.3wheelerworldforums.com/showthread.php?t=30686&highlight=power+valve

I wound up making a wedge adapter out of aluminum to adapt the Tri-z Intake to the YZ reed cage.. I did this cause I want to use the stock air box setup.. If you want you can just clamp a filter on the carb, problem solved..

http://www.3wheeler.org/3wheeling/12-84~pg38.html

After reading the article above, I was kinda bummed, they say the work wasn't worth it, and went back to a stock wildly ported setup.. :(

[Darius1502]

Let me know what you do with the pipe on this deal too

[Darius1502]

You lucky duck!! Please lets see plently of pictures....

Do you know if a modern (1998 to 2002) engine would also bolt in with minimal mods?

Thanks and good luck....can't wait to see the finished product!

[TRI Z Racer]

digger - When you powervalved your did you notice a significant difference in performance? is the artcile dead on about the low end totally sucking? I am still excited... just not as much now :(

Darius - i think ill end up keeping the pipe, i hope to get lots of pictures, it usually works out that i get too anxious to put stuff in and a camera just makes it take that much longer. I think ill have a bit more of an incentive to take pic this time though. :) All i know about the newer yz motors is that they are different. It would be just like trying to put a new yz motor in and yz 85 chassis, im sure there have been chassis mods. Im sure there are some similarities and some differences all of that comes with switching any motor into another chassis. One thing i could see being wrong is if the new yz kickers kick backwards then you would have to remove your plastics to start it. the reason the 83-87 yzs work out is cause you can put the tri z kicker gear in them to kick over forward. Thats about all i know as of now. hope it helps

Tyler

[Derrick Adams]

Well guys, I'll give you my outlook on it. On my bike, as soon as I switched to the DG pipe I lost my low-end power and never have found it. I have a feeling that venturing away from the small carb and stock pipe is what caused this.

Since my last post i've been doing some tuning on my bike. The first thing I did was add a set of performance reeds from Boyesson. That seemed to make the bike a little snappier, but nowhere near the low-end from stock. The next thing I did was go from my 34mm carb up to a 39mm. Now, I seem to have that same saggy bottom end but the bike really comes alive in the mid range and pulls higher than it ever has.

So, the bike is definately faster than it was, but not so much faster that a ported stock cylinder and big carb, on a stock Z.

As a matter of fact, some of the other guys say they've had to gear up the front sprocket to keep the bike under control, where as I'm actually dropping to a 12 tooth to get it to pull better out of corners.

I think chainsaw compares his to a stock Z, and theirs no doubt that it's faster, but a modded Z is very comparable.(In my opinion)

The biggest advantage to a powervalve motor is in Drag races. I can full-on dump the clutch in 1st, and it screams. Mainly because the bike has no low-end to speak of and it ramps up perfect for holeshots. It will power wheelie thru 2nd and 3rd great though.

If you want to see all the powervalved Z's in action, don't miss Trike Fest this year, because we'll all be there!

[Darius1502]

Derrick,

Great perspective. Thanks! Let's see what OrangeShee can add to this.

[TRI Z Racer]

did you ever change the flywheel over to the yz one?

also, im thinking the Z pipe has alot more to do with the low end loss then we think. if you throw on a pipe made for a tri-z onto a yz motor i think that is not going to give the same results as a yz pipe on a yz. pipes are tuned for specific engines, although the two engines have alot of the same features such as case and apearance, the cylinder is completely different inside and has a powervavle. i would venture a guess that if you put a yz pipe on your tri z that it would run like crap, due to that fact that they arnt made for it.

having said that i am not an expert on pipes, im still learning. so someone who knows more may refute everything i said. im just going by what i do know about combustion chamber design and 2 stroke design

what do you guys think

[diggerzmound]

I have never rode my Tr-Z. I got in in a box of parts and had access to a 85 YZ250 motor and thought what the hell.. I have tried to fit the YZ pipe, it goes the wrong way, the trike pipe goes to the left the YZ goes to the right... It would take some messing around to get the YZ one on. If you want to give it a try I got an aftermarket YZ pipe you could try. I would sell it cheap....

[Derrick Adams]

As far as I know, no-one is running the YZ flywheel. Although, I may try it someday.

[TRI Z Racer]

i know the pipe runs on the other side of the trike, what kind of mods were blatently obviosly needed. besides it runs down the wrong side of the frame? what kind of pipe is it either post here of drop me a PM

[diggerzmound]

The pipe is a PSI pipe, it was pretty beat up, I had a machine shop take it apart and straighten it out, It actually come out pretty nice.. $50 + Shipping.

http://www.imagestation.com/picture/sraid163/p89851d03b9667bfb727b639bde055a7c/f48f0f95.jpg

[TRI Z Racer]

any pictures of the pipe?

[crackshot]

what the hell is this "power valved" b.s.?

[diggerzmound]

what the hell is this "power valved" b.s.?

Nothing BS about it look up there are pictures explaining the entire operation. Yamaha built the 250 cc engine for the TRI-Z specifically for the trike. They built the exact bottom end with a power valved top end for the YZ250 MX bike.. Powervalves are flyweight controlled mechanisms that partially close off the exhaust ports to give 2 cycles more bottom end power. i think Yamaha designed the power valve in their dirtbikes in 1983, and they currently still use them in nearly all their 2 cycle recreational engines.. It just so happens everything will bolt up, with a very few modifications...

I will get pictures of the pipe tonight..

[crackshot]

show me valves in a 2 stroke.

[Darius1502]

Great shot of the motor....looks beautiful!!

[TRI Z Racer]

crackshot - if you look in the picture of the motor you will see 3 bolts on the side of the cylinder, the cover they hold on has a linkage under it and the controls for the valve. its not they type of valve your thinking of, the 4 stroke type, its more like the slide to a mikuni flatsliide carb only it doesnt close all the way. it adjusts your exhaust prot timing to give you more topend and bottomend. they have that same things on snowmobiles Arctic cat calls it thier "APV - Arctic powervalve" I think skii-doos is called "R.A.V.E." i know polaris has it too, but im not sure what its called.
hope that shelps ya

[diggerzmound]

http://www.imagestation.com/picture/sraid163/pe095e9c8d3e296a089c8106ed581d8c3/f48dfe79.jpg

See #9 that is a power valve... Jeez, disbelievers....

[TRI Z Racer]

lol... what are you gonna do, a few years ago i would have said the same thing.

i think you mean #12

[03 ORANGE SHEE]

1- tri-z motor 32hp ..yz motor 39-42hp
2- exhaust port on powervalve motor wider and taller than wrench report mods #1 and #2 this means more power stock than a ported tri-z motor period!(unless drag ported) my 83 motor has the big 8 petal reed cage and the biggest intake of the 83-87 motors
3- i have three times more bottom end and twice the mid -top pull as my wrench report mods (#2) will ever reach and the power is more contolable like a 4 stroke
4- i would not have wasted my time and money to do this if it did not make an improvement in controlable power gains
5- i recommend this mod to anyone who needs more trail rider friendly power, yet with a top end pull that will leave you shaking, but grinning at the same time
6- the dg pipe for the z is just a stock replacement , but is intended for bottom end, if you need top end , find a stock pipe and cut the required 10mm from it, it pulls harder on top than a dg

[TRI Z Racer]

well, that is reassuring, i like to hear stuff like that, do you run the yz flywheel? and what pipe do you run on yours?

after hearing that from O Shee i wonder if the problem derrick adams is having is maybe his powervalve is stuck all the way up, or mayeb doesnt fall all the way back down. that would account for horrible bottom end...

so the 83 has the biggest reed cage of the 83-87? or do you just mean it is much bigger then stock tri -z


3 days till my new baby (powervalved motor) is in my arms for good :p

[CHAINSAW]

Derrick is having some kind of problems, because mine only dynoed at 29 HP, but will still pull the front tires up and do a power wheelie in 4th gear.... with the +6 swinger!

[TRI Z Racer]

you last two guys have got me like a little boy on christmas eve. damn i cant wait to get that motor and pull some powerwheelies in 4th and 5th

i should have some pics of the engine on sat or sunday

i appreciate all the input guys!!!

[CHAINSAW]

yeah man. My YZ motor has a trike ignition, a hot rod crank, and what was supposed to be a drag port. Turns out, all the guy did was knock the paint off inside. I was also running a hybrid pipe that was made for a 370 Kit I had (sold to Louis) Because of the pipe, it dropped my HP. The power curve on mine was very weird looking, but I couldnt tell racing. All I did was drag race mine. It was very fast for a 250, but once I get the right person to port it, it will scream. The guy Im working with now thinks we can get close to 60-65 HP out of it no problem.. maybe even 70. (He used to race mini sprints with YZ motors)

[TRI Z Racer]

ill know who to talk to when i am looking for even more power!!!
i am seriously considering running the yz pipe. i think i can get it to fit good and not rub on anything. i think that will make more hp then running the tri z pipe. what does the hot rod crank do for you? is it lighter, or are the edges sharp to reduce windage?

[CHAINSAW]

not sure what the difference is on a stock one.. but mine has a few mods done to it ;)

[diggerzmound]

THe Hod Rods rod are made by Wiseco, they are just a stronger then stock replacement...

[03 ORANGE SHEE]

the 83 reed cage and intake is larger than the other years,( more flow),this is the turbo crank in mine, very light and has been knurled i run a dg in the woods, and a outframe jemco pipe for the dirt drags

[03 ORANGE SHEE]

here is a 83 cylinder, and a z one

[Darius1502]

orangeshee,

The other day I notice some tranny oil on my crank. I assume this means crank seal leak on the tranny side. Did you notice that on yours before you changed the crank seal?

Is that why you're changing it?

[03 ORANGE SHEE]

darius,i am changing mine because at an idle is flows oil out the overflow tube, and if i blip the throttle it races out

[Darius1502]

Nathan,

Would a crank seal leak make the smoke white?

[03 ORANGE SHEE]

ive never had that problem, i have had excessive smoke (white) due to a leaky headgasket, i found out when i popped the cap off when it was cold one day, and antifreeze came running out the cap when i first started it

[Darius1502]

oh yeah...you told me about that....


I'll go check it out

[Darius1502]

Nope mine does not do that

[TRI Z Racer]

i am picking my engine up tonight in about 2 hours, but i thought i would start stripping my z's bottom end to get all the good parts and make the best bottom end i could out of them. i have never split the cases on my z untill today... and i got a nice surprise. the guy i bought it from never mentioned anything about a lightened crack. atleast it looks lightened to me. here are some pics. there are alot of tooling marks on it and whatnot. tell me what you guys think. you think its alright to run it. ive been running it for 2 years with no problems so far. just wanted to show you guys some pics and just double check

[03 ORANGE SHEE]

that is bone stock, the holes are drilled to balance it, a lightened crank has about ten holes in it the diameter of those large holes

[TRI Z Racer]

good to know hmm. just picked up my motor, more pics to come