Hey guys, ive had my Yz now for about a month and this winter when im not riding i wanna do a new top end on it. I wanna keep it a 250 so just stock piston. What do i need for top end. Piston hesd, rings, wristpin but what about if the jug is all pitted out and stuff? Do i need a new one every time??
Rebuilding Yz 250
- Thread starter smerch69
- Start date
You'll be looking for gouges, chipping, or cracking of the nikasil coating typically near the ports edges. Any chipping of the nikasil and it needs a recoat. $200-275.
If the cylinder bore and crank bearings checks out, you'll need a Piston, Rings, Pin, Pin Bearing, Top end gasket set. You should be able to acquire all this for $100-160.
Check the top of the piston for the current size. There may be no marking (standard bore), a zero (standard bore), or a +something (oversized piston). You'll need to buy the same piston as installed. -BIG DAN
If the nikasil is worn thru anywhere you need to replace also....if your unsure, a good test is to take a metal pic and try to scratch surface of cylinder, if you can it's done.