piston to cylinder clearance, need to know!

[scofflaw]

machine the cyl like a 4 stroke.
your going to do pistons twice.

Some relief around the exhaust port your good. not rocket science.

[rodbolt17]

NO
if the machine shop does not KNOW what you need .
find another shop.
two I can recommend is ron's marine in portsmoth VA, or Carolina machine In Wilmington NC.

most customers cant fix the mechanical parts much less tell the machine shop any usefull info.

[ausnoelm]

Exactly right, if you don't know exactly what you need , don't drop it off at a machine shop.

So, by that reasoning, when you take your motor in for repairs, you have to tell them what to do, what parts to replace, wonder why people bother becoming (say) a master tech, because the owner has to tell you what's wrong, or you find another shop?

[rodbolt17]

after boring the intake and ex ports must be chamfered,
if to little is chamfered the rings grab the sharp edge and your fresh rebuild turns to scrap iron.
if to much is chamfered the rings expand into the port and your fresh rebuild is scrap iron.
you have to find a machine shop that knows how and why.

[scofflaw]

So, by that reasoning, when you take your motor in for repairs, you have to tell them what to do, what parts to replace, wonder why people bother becoming (say) a master tech, because the owner has to tell you what's wrong, or you find another shop?

So seeing this thread is about piston clearance, I assume the OP stripped the engine down himself and plans on reassembling himself. One does not need to be a master tech to accomplish this. Not everyone with a failed engine has the talent to pull this off and those are the people that need a reputable source for the repair. But don't think everyone is helpless.