Business question for the seasoned Engine Builders?

[Robbins Racing]

Yes, of course I was just clowning. Racers are notorious for pushing things beyond their limits in desperation, ignoring all good advise. I keep the engine rich and cool at idle with no load for the first couple of minutes to let the parts smooth out just a little. Even if you have enough cyl to piston clearance you can still damage the seal between the piston ring and piston. If you've ever seen aluminum stuck to the bottom of a ring you know what I'm talking about. Also, don't try to get you clearance from break in, you have to hone it in. Break in is just for smoothing and mating the parts. Hope that helps.

Yup I honed and set clearance prior to breaking it in, same clearance I've set on all the engines of this type I have built.

 

[Bradley71]

Ive never had that happen.i burnt a hole in a piston size of a quarter by listening to someone on bobs saying tkm pistons will work in a parilla sudam.
Ask kermit if he blows one on a dyno if he boxes it up and sebds it back to you in pieces what he says.he will say absolutely not.hes in business of building motors.and hes a yr behindi talked to them last week he has 27 motors on the shelf just for rebuilds

 

[Evanguy]

Not a 2cycle engine expert by any means…what does “cold seized” mean? Thx! dr

Seize before even up to temp or the pistons faster then the bore.

One time when I was young I had an 88 cr250 that I rebuilt twice before realizing the issue in my case. My 88 had a cast sleeve that replaced the nikasil lined bore. So the wiseco piston called for 0.0015 ptw, cold seized both times on first run. Later I realized the none OEM sleeve needed none OEM ptw. I went with 0.003 and the bike lasted years.