1985 yz250 top end rebuild help

[tylerandreasson]

ok so i have a 1985 yz250 i just got, and the guy i got it from told me it needed new piston rings because the radiator got kinked, which it clearly was. so i took the top end off and i looked at it and the piston rings are pretty much gone on one side, almost like melted into the piston.. so i thought i could just buy a new piston kit, but someone told me since it is a 1985 that it is almost sertanly bored already.. so i looked on top of the piston and it says "mm .50"... does that mean it is at 68.50mm since 68 is the stock size? also the cylinder was scratched where the piston had beedn rubbing on one side. could i just get that honed? and then just put a wiseco 68.50mm piston kit in it?
tell me what you think..
Thanks,
Tyler

 

[Ol'89r]

I think you need to take your parts to a shop or motorcycle machine shop and have everything measured. If the piston and rings are that bad, your cylinder will also be damaged and will probably need to be bored. There is also a good chance that pieces of your piston and rings got down into the bottom end. The crank and main bearings should be checked too.

 

[whenfoxforks-ruled]

If you are keeping it, send it to Forward Motion. Once its properly set up, then you should be able to maintain it. Vintage Bob

 

[tylerandreasson]

how much would it roughly cost to send it?

 

[whenfoxforks-ruled]

how much would it roughly cost to send it?

There may be some online prices from the post office or UPS? The top end will depend on what it needs, and what you want. Call Eric for pricing.

 

[tylerandreasson]

thanks alot. im going to check out the bearings and crank on the bottom end and go ahead and send it in and see what they say i need to do. :nod: