Oil from the carburetors

Hi have been getting an ongoing issue with oil drips from the carburetors. Seems to be on all four. In the past there was an issue with stuck needle valves but fixed that a long time ago and I don't think this is an issue anymore. Seems like there is some kind of mist maybe. This oil has a mix of fuel with it, but since it is coming from the carbs that is to be expected. The oil site level always seems to come back to normal when checked after it cools after a ride. And I can't smell fuel at the oil filler cap. I suspected the oil breather so I moved the breather filter away from the carbs. I also tried to take the breather apart in order to clean it. But, I couldn't take the two screws out, not even with an impact (impact is at an angle cause the frame top is in the way). So I just shot some air in the passages. It seems like since then I have made things worse and it now smokes when I first start it. I imagine from the oil sitting in the carbs. Here is a picture of the oil site right after a 10 min ride.



I still suspect some kind of oil vapor pressure having to do with a malfunctioning breather. Any idea's anyone? Or am completely of track?

O.K., did some research on the foam. Found the following:

"Bubbly is normal. Your oil is returned to the tank and gets pretty aerated. The oil retuirn line is at the top of the tank.

The oil supply line is off the bottom of the tank, so by the time top oil reaches the bottom, the bubbles are gone, or remain on top and are harmless. It's normal.

A tanish, milky "foam" is water mixed with oil.....common with cold weather riding, especially with a bike taken from a heated garage into cold temps. It will disappear after the engine is warmed and the moisture in the oil is "cooked" out and disepates via the head vents."

Today was the coldest I have ridden this bike, about 55 degrees. And was in the garage. O.K., so not worried about the foam and have never noticed it before. So I guess the oil in the carburetors is the main thing I need to concentrate on.

Could be that with the foam, it is getting into the airbox through the breather, then sucked into the carbs. Did you crack the filler open and see how high the foam is. Thinking out loud.

Haven't noticed any foam at the filler. But I don't think the foam is an issue any longer. From what I have gathered from other posts, foaming is normal when taking a bike from a warm environment (garage) out into cool weather. I never had foam issue before today and it is cold out. As for the breather, no air box but pods. I have routed the breather filter via a hose, same as the carb overflow hoses. So it now resides near the center stand.

The oil shouldn't foam. What are you using? Ed

KZJOE900 wrote: ... As for the breather, no air box but pods. I have routed the breather filter via a hose, same as the carb overflow hoses. So it now resides near the center stand.

Perhaps compression in at least one cylinder is low due to being lost into the crankcase and causing excessive pressure inside the crankcase which escapes through the breather hose exiting underneath the bike.

Could help confirm such condition by performing a compression test on each cylinder, followed by a wet compression test on each cylinder.

Could also perform a leak down test -- even a poor man's leak down test would suffice -- to determine extent of blow-by from each combustion chamber into the crankcase, by listening to the volume of air escaping from the crankcase breather vent.

Good Fortune!

Patton wrote:

KZJOE900 wrote: ... As for the breather, no air box but pods. I have routed the breather filter via a hose, same as the carb overflow hoses. So it now resides near the center stand.

Perhaps compression in at least one cylinder is low due to being lost into the crankcase and causing excessive pressure inside the crankcase which escapes through the breather hose exiting underneath the bike.

Could help confirm such condition by performing a compression test on each cylinder, followed by a wet compression test on each cylinder.

Could also perform a leak down test -- even a poor man's leak down test would suffice -- to determine extent of blow-by from each combustion chamber into the crankcase, by listening to the volume of air escaping from the crankcase breather vent.

Good Fortune!

I would guess that is the most probable situation. I know last I checked the compression was 115 all across. Haven't checked it since tearing the top end and putting it back together. I guess I will have to live with it until I install new piston and rings along with the required boring. That won't be until next summer. I may do the compression test and leak down test again just for kicks. I guess I was hoping it was something simpler like the breather itself. Thanks for the info Patton.

Ed, the oil I have in there is Valvoline motorcycle oil 10w 40. But if what I read on the net is correct, the foaming was due to moisture in the oil along with the warm / cold running of the bike. In other words, I started in a warm garage and rode in cool weather (50 to 55 degrees) for a 10 min ride. Not what I read is bs or not, but I am hoping the foaming is not an issue.

KZJOE900 wrote: if what I read on the net is correct, the foaming was due to moisture in the oil along with the warm / cold running of the bike. In other words, I started in a warm garage and rode in cool weather (50 to 55 degrees) for a 10 min ride. Not what I read is bs or not, but I am hoping the foaming is not an issue.

I have ridden in much colder temps than that and never saw foam in my oil.

Do you not have any breather on the bike?

That will let condensation get into the crankcase.

Yes, I have one of those red breather filters you can get from Autozone. Maybe the humidity down here is a factor and the fact it was such a short ride and there was not enough time for it to evaporate (cook) out of the oil before shutting the engine down. I don't know. But I will warm up in the next day or two and I will go for a longer ride and check it again afterwards.

The Valvoline 10w40 motorcycle oil should work very well, so I'm sure that's not an issue. The longer ride will probably boil off the moisture and reduce or eliminate the foaming. Ed