1980 atc 110 cranckcase pressure/ smoking

[grit]

I recently rebuilt my atc 110, completely tore down,cleaned,new piston & rings , new valves. After I got it running I found it was building up crankcase pressure. After some research I found it doesn't have a crankcase breather, so I put a breather in the intake valve cap. It is not building up pressure now, but at higher rpm's it smokes.If I let it idle it doesn't smoke, only at high rpm's. Any suggestions?

[harryredtrike]

how much oil did you put in?

[cr480r]

poor ring seal... what preparation did the cylinder recieve? was it in good condition? fresh bore? hone? is it over filled with oil?

[grit]

the oil level is correct. It is a new bore with a 2nd over piston. I pulled the top end and double checked everything. It doesn't come stock with an intake valve seal and one theory is to much oil to the intake valve due to the breather.

[cr480r]

the oil level is correct. It is a new bore with a 2nd over piston. I pulled the top end and double checked everything. It doesn't come stock with an intake valve seal and one theory is to much oil to the intake valve due to the breather.

was the bore honed properly? did you measure any ring gaps? are the gaps staggered? i dont understand how the breather would change the amount of oil in the top-end.. So i would rule out the breather as culprit.. excess blowby and crankcase pressure is from poor ring seal... smoke is from oil consumtion...

[harryredtrike]

since your new is the smoke white or black?