BIG BORE KIT TRI Z!!! 92 YZ cylnder similar to the Tri Z?

[Darius1502]

Wondering about Big Bore kits and ran across this:

YZ 250 KITS

270CC--YZ 250 A-MAX KIT 1992-1998 (Bore 70mm)
Stage one: $500.00 uncoated piston and uncoated head.
Stage two: $575.00 Xtreme piston and head coatings.
Stage three: $700.00 Fully ported, with Xtreme piston and head coatings.

292CC--YZ 250 BIG BORE KIT 1992-1998 (Bore 74mm)
Stage one: $650.00 uncoated piston and uncoated head.
Stage two: $725.00 Xtreme piston and head coatings.
Stage three: $850.00 Fully ported, with Xtreme piston and head coatings.

If the piston from a 92 can be used on the tri z and the cylnder can accomdate the additional boring...then maybe it will work.

Any motorheads have some answers???

[TRI-Zbrian]

yeah id like to know also nice work finding this info out. that would be sweet to have a big bore kit.

[KASEY]

I talked to a guy in the dunes once that had a 300cc kit on his tri-z,, since i am not a tri-z guy i didn't really press him for details ,,, i could see that the cylinder was not a stock unit ,,, sorry i guess i should have asked more questions,,,,,

[J.D.]

A Z cylinder can only be overbored 2 mm before resleeve is required, so the top one would just fit if you bored it to max. Maybe LA sleeves can do a custom sleeve to accomodate this???

[TimSr]

On a "big bore kit", the sleeve is removed, and the larger one installed. It has nothing to do with normal overbore limits.

[CHAINSAW]

How does the powervalves work though.?? Dont they run by gears, or electrical?? I dont know a thing about them because Im to scared to tear into my bike.. lol Id end up not putting something back the same, and tearing stuff up.

I know how they work, but can anyone explain what powervalves run on, and can they be ran by a bottem end that is not built for them?

[TRI-Zbrian]

they run off of a gear in the lower case and yes they can be made to work with the tri z lower end every thing is there except a couple parts from a yz 250 but it all bolts up from what i have been told. im doin gthis but im not using the power valve set up i have to plugs in my yz cylinder ware the poer valve used to be it should still be a nice improvement over stock.

[CHAINSAW]

Ive been wanting to build a Tri YZ for a while. When I do it, Im gonna just put a YZ motor in. Every 5 speed Ive ever rode feels like it needs a 6th gear, but every 6 gear has no balls in it. A good ole powervalved 5 speed would be plenty for me I think.

[TRI-Zbrian]

i was also pondering with that idea amagine a 2004 yz 250 engine in a tri z with all the mods and aftermarket parts you can buy it would be so bad ass. soem one with money needs to do it .

[mywifeknowseverything]

I asked the same question of a friend of mine and this was his reply...

as far as the tri-z versus the YZ is back in the day my cousin put a "85" YZ PowerValve Cyl. on his Tri-Z to maybe think or hope it was faster "back when we used to sand drag" ...he ended takeing it off cause it was slower ...

[Tri-Z Pilot]

Trinity racing will make you a custom 350cc stroker kit for your tri-z.

[J.D.]

On a "big bore kit", the sleeve is removed, and the larger one installed. It has nothing to do with normal overbore limits.

Sorry for speaking out of my ass. Oh well, learn something new every day. I just assumed they bored it out, I guess that does explain why the price is so high though.


Tri-Z pilot, how much does Trinity want for this kit?

[CHAINSAW]

If I had the money, sure a YFZ450, or a 350 kit would rock. But when you can pick up a YZ motor for around $200 running, and since Im cheap.. lol thats probably what Im gonna do.