New Rings in - puffin from the breather?

[aerojack7654]

Hi folks,
I just got my Dream engine back together with the new rings installed to address a oil burning cylinder following it's resurrection, and turning the rebuilt engine over I noticed that there was air puffing out of the breather tube (low pressure but definitely there). Now I'm assuming that I'm somehow pressurizing the crankcase, either with ring blowby or head gasket leaking. My wishful thinking side hopes that the rings are just not bedded down, and that this will be addressed by running the engine, but my pessimist side says "fuggedaboutit". I'm puzzled how this could happen, I was pretty meticulous about getting the rings in the bores, gaps properly aligned, everything moved smoothly, I had a new head gasket (and as Bill Silver said, no gasket sealer anywhere). The liners look ok, not sunk, and yes I put new standard rings on the original standard pistons (no marking on the top).
Anybody got some insight? Should I just go ahead and try and start it?

Thanks!
Jack

[Tim Miller]

Did you hone it?
Yes, I would go ahead and run it to seat the rings in.

Tim

Hi folks,
I just got my Dream engine back together with the new rings installed to address a oil burning cylinder following it's resurrection, and turning the rebuilt engine over I noticed that there was air puffing out of the breather tube (low pressure but definitely there). Now I'm assuming that I'm somehow pressurizing the crankcase, either with ring blowby or head gasket leaking. My wishful thinking side hopes that the rings are just not bedded down, and that this will be addressed by running the engine, but my pessimist side says "fuggedaboutit". I'm puzzled how this could happen, I was pretty meticulous about getting the rings in the bores, gaps properly aligned, everything moved smoothly, I had a new head gasket (and as Bill Silver said, no gasket sealer anywhere). The liners look ok, not sunk, and yes I put new standard rings on the original standard pistons (no marking on the top).
Anybody got some insight? Should I just go ahead and try and start it?

Thanks!
Jack

[aerojack7654]

Yes, I honed the cylinders with a medium hone. I used one of those spring/stone types hones, which was pushed in pretty far so it had less pressure on the cylinder walls possibly, bqut I honed for a while until I got a pretty consistent cross hatched pattern.

[flathead]

Hello,
The dream engine has a 360 degree crank. Both pistons are rising and falling at the same time. When you turn the engine over you are compressing 305cc's into the crankcase. It has to go somewhere. I assume at normal engine speed for the dream that this effect is pretty much cancelled out due to the fact that your sucking out 305cc's when the pistons rise. I've got a 250 scrambler with a dream crank in it that we flat track. Crankcase pressure is a problem with this one at higher RPM and does cause seals to weep.
Mark

[aerojack7654]

Thanks Mark,
I hadn't thought of it that way, but unlike the 180 crank, which trades equal volumes of air as the pistons go up and down, the 360 crank will inhale and exhale somewhat as the motor rotates. I'm going to see if the exhale coincides with BDC, then I'll at least feel better about going ahead and putting the thing back in the bike and trying it out. Thanks for the insight!

Regards,
JAck