Crank case vent: How much smoking is ok/too much?

Thanks for the replies, guys. I don't recall an odor standing out, but I'll have to check the odor tomorrow since its a bit late.

I ran conventional oil for the first 800-1000 miles and drove it as hard as I could on the street to break in the rings. I want to say I noticed the smoke just before I switched to synthetic oil, so there is no correlation with oil type and smoke.

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Broken ringland, stuck rings and mismatched pistons, That's what caused my smoke.

That's a substantial amount of smoke! I'm not anywhere near that. To even see it at the vent, I have to shine a light through it...

Other than doubt a wet/dry compression test, is there another way to check for broken rings?

A leak down test would tell you if you have an an excess of combustion gasses able to leak past the pistons rings and if so which cylinder.
You should google the process and equipment needed to perform the test, but the long and short of it is....

Compressed air is introduced in to the cylinder through the spark plug hole.
Some of the compressed air will always escape past the rings due to ring end gaps on a "perfect" cylinder bore, but excessive air leakage will be shown on the leakdown
gauge. If excessive air air loss is shown. You can then listen to identify if the air is escaping through the intake or exhaust ports (bad valve seats, incorrect timing, bent valve..etc), or if you hear excessive air hissing from the crank case breather port, that means incorrect ring gaps, a broken ring, broken ring land....or it's even possible that the rings have rotated to where the ring gaps are all aligned and it is a path of less resistance for the air to escape.
If the leakdown test shows all cylinders are all within normal limits, then you may just have to ignore it until it becomes worse. I have a feeling that numerous older/rebuilt engines pass vapor such as this, but it all disappears into the airbox and gets reburned and the owner is oblivious. It can go unnoticed for years until it becomes so bad that oil begins
pooling in the bottom of the air box, or until they switch to pods.

Just food for thought.

Thanks draft. I'll acquire the stuff for a leak down test and try to get it done this week.

A leak-down test injects air pressure through the spark plug hole to pressurize the combustion chamber.

Can perform a poor-man's leak-down test by introducing compressed air into a spark plug hole and listening to where it escapes from the combustion clamber. This may be done at TDC or any other cam positions where both valves are fully closed. Top dead center (TDC) is when the piston is at its highest position. An easy way to tell TDC is by alignment of the T mark with the case mark when viewed through the timing window.

May introduce a spurt of compressed air by using a rubber cone-tip blow gun (rubber air nozzle) held into the spark plug hole. And of course keep holding it in position to keep air from coming back out the spark plug hole while listening for escaping air at other places. The air compressor should not be running while listening because the noise will likely drown out any sound of escaping air. Or just use a portable compressed air tank.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates loss of compression past head gasket (perhaps due to a blown head gasket).

A leaking valve may sometimes be resolved by adjusting the clearance to within specs.

A leaking head gasket may sometimes be resolved by torquing the head fasteners when the engine is stone cold (such as after sitting overnight).

Good Fortune!

Is it for certain that the crankcase oil hasn't become contaminated (diluted) with gasoline?

When this happens, it may cause smoke out the exhaust and out the crankcase vent.

Even with perfect leak-down test results.

Good Fortune!

Thanks ,Paton. I'll likely just borrow a leak down tool from autozone since there is one just around the corner. It would give me peace of mind knowing a ring issue is ruled out.

I have no smoke from the exhaust and no smoke from the case vent when the bike is cold.

I would think the smoke would be present at both warm and cold temps if it was a ring issue. It really only happens when the engine is warm, which supports oil contamination issues.

Did the bike sit for a long time. If so, it might clear up after running it for a while.
Steve

It hasn't sat but about 2 weeks over the last few months. The 810 kit was put in about 3-4 months ago.

It doesn't look like a lot to me. Put a filter on it or route a hose to chain area for oiling. If it runs good ride the piss out of it. :lol:
R

It's possible the rings were installed wrong or broken.
Steve

With my 810 kit I get a little blow by smoke out of the breather after I bust it's ass pretty hard.
I run a small k-n type filter on my vent it get's oily and I see a little smoke from time to time
but don't worry about it much.