Is is common to have smoke out the exhaust after a top end rebuild?

Bored +.010, new pistons/rings, 5 angle radius valve job with street port and .060 off heads.

 

If you are talking about immediatley after the first startup it could just be assembly oil burning off, after that I would say it is definately not normal unless it is black smoke from an overly rich condition which is not normal either but easily corrected.

 

How much smoke? Some on the first start up after the rebuild would be normal. A puff on every start up after that could be a leaky valve guide or bad valve guide seal. If it smokes all the time the engine is running, you've got a ring problem. Let us know what you find.

 

Well...I just finished heat-cycling it. One minute...two minute...three minute...four. Allowing full cool-down in between. I didn't watch for it, but I did video the startup and there was a good puff right away...then at shut-down. I didn't watch for it on the 2 min run either. The 3 min run I again recorded and it was more than just startup. On the 4 min run (just completed like 20 minutes ago) it was dark...but I could see smoke in the headlight. It's mostly at idle...can't see it above idle...might still be there though. Tomorrow I plan on a first ride....should I?

 

Did you do build or someone else? If you did it are you sure scraper ring with dot on it was installed on both pistons facing up? Carbed bike? If so what jetting/needle? Sounds like more that assembly lube burning off. A bad off fuel mix will cause light smoking so don't panic yet.

 

I disassembled the engine and delivered the cylinders and heads (with valves / springs still installed) to an indie shop where the cylinders were inspected / bored and the heads disassembled / inspected, cleaned, ported, valves / seats ground and shaved.

I reassembled the engine. I made it a point to double-checked the orientation of the middle rings...dot up / bevel down and in.

It's carbed with a 27.5 pilot jet in a Mikuni HSR42.

I'm thinking after work today I'll take 'er for a ride and try getting some load on the rings in hopes that it'll force the rings into the cylinder walls.

 

get into 3rd gear and WOT from 30 mph to 60 mph and then release down to the 30 mph and then WOT back up to 60. Do this ten times.

 

Just got back from my first post-build ride. Man that feels good! I missed my Dyna. 71 miles of pure bliss starting with the 30-60-30 X10 routine. Power felt good.

Still smokes though. I had another guy following me for the first 40 miles. He said he only saw smoke right out the lot and never saw it again till the resteraunt parkinglot.

I think I'll just keep riding for now and keep an eye on the oil level to see if it's using.

How long does it take before a new pipe quits smoking?