YZ cylinder on Tri-Z

[Groundworx]

I have heard of people using a YZ250 cylinder on the Tri-Z. I guess to get the powervalve. How hard is this, what kind of modification, if any, has to be done? Seems to me it should just be a bolt on mod. Also, what all do you get by doing this? More top end or???

[MTS]

Do a search Derrick adams did a whole step by step for it on the fourms here im also currently workin on puttin one togther for my Z.

[TRI Z Racer]

not too hard if you are comfortable taking off the right side (kicker side) case and installing a couple bearings and whatnot. If you switch out the cylinder your probly gonna either need the piston from that cylinder or get the cylinder honed/bored and a new piston.

depending on the year of the yz motor some of the intakes on the yz cylinders are angled towads the left side. this makes using the stock airbox pretty much impossible, its also a tight squeeze for a pod filter. one member on here had a piece machined to correct the angle and have the carb come straight back. I dont know anything about it other then i saw it in pics.

Also i know on my yz cylinder the exhasut flange is about 3/16th smaller in diameter then the flange on my pipe. I had to turn a spacer on the lathe to make it fit right.

I also encountered a problem with running the coolant line that connects the bottom of the radiators, the coolant line went right through the top pipe spring mount on the cylinder. The extra material on the cylinder due to the powervavle takes up a bit more space and makes coolant lines and conections cramped. i had to cut it off and reweld it a little further down so the coolant line didnt wear through in a day.

These are just a few of the problems i encountered personally. All of them were easy fixes and should not deter you if you have the desire for a powervalve motor. Aslo make sure you check out derrick adams write up it was very well done.

Hope it helps

[Groundworx]

I did look at his write up. He didn't seem to happy with the end result. It also sounds like it might be easier and you would get a better end result by just using the whole YZ engine. I knew most of what Derrick Adams wrote up, I mainly was wondering what all I would get out of the powervalve. Performance wise...

[diggerzmound]

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

Its more then just the powervalve components that need switched. The 85' bike motors have a left swept intake, so I had a wedge space made to square it up, I am using the stock airbox, the simple solution is to clamp an air filter on the back of the carb. The pipe flange is also smaller on the YZ engine, I had a spacer, looks like a bushing, made to take up the space. The YZ flange is smaller then the tri-z flange, so the pipe is too large.

I never rode my Z with the Stage 2 ported stock cylinder, but I know it is an animal with the powervalve cylinder..

[TRI Z Racer]

if you talk to 03OrangeSheei think he is real happy with his powervavled Z. I know his put the whooping on mine at Trikefest 05

[03 ORANGE SHEE]

thanks tyler, i am happy with it, i use a 83 yz motor , big straight intake track, 8 petal reeds, like my quadzilla, and the old head is even the same a z, so theres no problems with coolant line hook-ups and engles
at tf05 , the motor had no porting, just a re-chambered head and 93 octane pump gas, stock swinger and it ran one bike lenth behind jason halls stretched 310 drag atc250r in300 ft!!
i have since put the six speed gears, forks, and drum in mine and plan on leaving the motor non- ported, way bother with a good thing!:w00t: the flange thing is the same size on my 83 motor , the only thing that is differnent i noticed is the same pipe springs dont have the tension they used too because the casting on the outside of the cylinder is larger in diameter thus closer to the spring mounts, and i dont have any leaks up there either.

[Groundworx]

So you used the whole YZ engine and no problems with the pipe mounting up?

[03 ORANGE SHEE]

yes , i used the whole 83 motor, EVERYTHING bolted and lined up like factory!

[Kintore]

I didnt know then bolted straight up! WOW!

Time to start looking for a 83 yz!

[CoeShow]

Just FYI. I used to be pretty close to the factory efforts back in those days. Guess what I saw at one of the supercross races back in 85-86? The "Factory" Yamaha Supercross riders were using Tri-Z cylinders on their bikes!! Thats right!

They went as far as making mock cylinder covers so that the engine would "appear" to have a functioning power valve.

I can't say how long or at how many races they ran that set-up, but they wouldn't have been running it at all if the riders didn't feel that it worked. At least until they found something better.

[MTS]

Just FYI. I used to be pretty close to the factory efforts back in those days. Guess what I saw at one of the supercross races back in 85-86? The "Factory" Yamaha Supercross riders were using Tri-Z cylinders on their bikes!! Thats right!

They went as far as making mock cylinder covers so that the engine would "appear" to have a functioning power valve.

I can't say how long or at how many races they ran that set-up, but they wouldn't have been running it at all if the riders didn't feel that it worked. At least until they found something better.
Thats Intresting! but none the less i decided im going to upgrade the Whole Z motor........:naughty:

[BigGreenMachine]

Have to know, how so?

[Red Rider]

Thats Intresting! but none the less i decided im going to upgrade the Whole Z motor........:naughty:You must be switching to a Honda mill. :naughty:

[Derrick Adams]

Actually, the 250R engine is pretty much a bolt-in deal for the Z. Best engine mod you can make. 6-speed trans, counter balanced engine, lots of aftermarket parts available... plus you can usually find them for around $600 on e-bay!