250r fried piston????

[joe22883]

Yea im paranoid but it is the first top end i have done on the bike and when he told me he just did one and it lasted him only 10 hours i got worried. The more reading i do though i think it was the machine shops fault they bored it too small.And when i talked to him he said he had some old retired guy do it for him so i dont knwo if he meant in the guys garage or in a shop.

[ky 2stroker]

the best thing to do when you need to get your cylinder bored is to first order the correct size piston and take both the piston & cylinder with you to the machine shop so as they can measure the piston and match it to the cylinder, that way you get a perfect fit.

[joe22883]

Yea that is what i did i measured teh cylinder ordered and then my machince shop did the work.IM not worried about my machine shop there are really good. I just didnt want it to be another problem that caused a premature life on a new topend. But im a little less worried now that i have more info.

[BlueDiablo]

machine shops around here wont even think about boring a cylinder unless you have the piston. Just make sure your run a rich mixture during break in and check the torque on the head bolts. I run two tanks at 20:1 through mine before i even move it. Takes alot of time but it seems to work for me. To each his own tho right.

[joe22883]

Yea neither will my shop he wont touch it without the piston.Im running 32:1 right now. What should i run for normal riding?

[BlueDiablo]

I run 32:1 with R-50 but 40:1 would be fine.