Hi All,

I just bought a project from eBay and am trying to decide what is the best way to proceed.
The head has a missing exhaust valve top, but the head looks undamaged. The stem is in place with the spring assembly in tact. The head and jug was pulled by the previous owner. The cylinder got wet and has surface rust. The cam chain is gone and the cam broke. The replacement cam was left outside and has surface rust on it as well.
I figure I can clean up the cam, but am wondering if I'll need a bigger piston after cleaning up the rusted sleeve. Also, since these used endless cam chains, do I have to dismantle the whole thing to put in the new chain? (I was hoping it was a rivetable chain.) Beyond that, if the trx 300 uses the same cylinder and uses the same overbore pistons, can I easily bump up this engine to a 300? I've looked thru the previous posts but have not found any details on the similarity of the 250 and 300. By looking thru an online parts catalog, I see they used different heads, but do not know if it is worth it... Any suggestions would be appreciated, and if you have any parts, I could use a gas tank.

Thanks,
Sparkfarmer