Thinking about Tri-Z 490 conversion

[Tri-Z Pilot]

I think I want to take the engine out of my yellow tri-z, and use it for a parts engine and stuff a yz 490 in there. My questions are, how hard is the conversion? Are the 490's reliable? Powervalved? (I know they are air-cooled). What kind of powerband? (bottom, mid, top?) And lastly, how much will a decent 490 engine cost? (including exhaust, carb, the whole deal).

[CHAINSAW]

Sounds like a lot of trouble, to have an air cooled motor. Dont get me wrong, they are fast motors,.. but are a real bear to start. 1bad350X (doesnt come to this site much) has an old conversion frame. It was a YZ490 converted into a trike. That would almost be easier, then trying to stuff that motor into a Tri Z frame. No, the 490's are not powervalved. The other thing, a stock exhuast probably wont bolt up. So you might find a motor for $200-$400, but your pipe will be up over $300 alone. And thats only if the motor CAN be crammed into the frame.

Seriously look into YZ motors. A good handfull of us have done it on this site, and there is a good reason. Its pretty simple (direct bolt up for a lot of years) , parts would be easier to find then 490 parts, and with a port n polish, that little 250 will be just as fast as that 490. You want it for drags, it can be geared and setup to be faster.... :)

[cliff2302]

i dont think anyone makes a 490 piston anymore because my friend has one and cant find a piston. also, i heard that big bore air cooled 2 strokes are prone to failure. that i just what i heard though. good luck