Gas in oil won't go away

I have some strange problem with gas getting in my oil on my XJ550 SECA. I have Done the following:

1)replaced my float needle jets with a brand new set and rebuilt carbs w/lower carb rebuild kit.
2)Wet synced carbs 3 times to make sure.
3) rebuilt the petcock with kit/new rubber parts
4) changed the oil 3 times now
After this last oil change I immediately started up the bike and rode it a short loop around the block, then immediately checked the oil for the gas smell. It smells like gas?? The crank case exhaust vent is vaporizing steam like crazy, probably about that of a person exhaling a cigarette. The steam smells like gas. What the heck is going on here? The gas pretty much had to accumulate in the oil while I rode it, is that even possible? Help a guy out here if you know what might be happening. It's riding season in Boise. I am afraid to destroy the bike though w/gas in my oil.

 

Oh yeah I also bench tested the carbs with a gas source hooked up to make sure gas is not flowing out of them. It passed.

 

Just flying blind here, but maybe the petcock is malfunctioning & letting gas down the vac' line.

 

Very good possibility. Here are some others:

Did you replace the o-rings on the outside of the float valve seats? It could be dumping fuel past the float valves and it wouldn't necessarily reveal itself during a wet-set.

Is it possible one or more enrichment plungers isn't shutting off completely? Again, this would not reveal itself doing a wet-set on the bench.

Or, the breather is plugged/kinked; or the air filter clogged up;

OR--- have you seen this? http://xjbikes.com/Forums/viewtopic/t=31872.html It could affect breather function.

What do your plugs look like?

 

bigfitz I appreciate the response here. I did replace the whole valve unit including screen needle oring and brass cylinder. Not sure how to test and see if these new parts are working correctly or not but things are clean and free moving when I inspected it visually.

Regarding the breather, you are speaking of the crankcase right? It did have a plastic like build up in the tube when I first inspected it. Not sure what the heck that was?? But I cleaned out the tube and it is smoking so it must not be clogged.

Plugs are dry and slight tan. Seems good and the bike idles great.

I checked the link but my bike has no airbox at all. It is removed and the breather has a little filter on it. For my air intake I am using a new K&N. Should be clear.

My real confusion was that it seems gas entered the oil while riding. I immediately rode for 15min after changing the oil and then checked the breather before turning it off, decent amount of fumes are coming out smelling like gas. 3 oil changes now so it seems it couldn't be remnant fuel.

What can I do to try and nail something down?

 

This may be a dumb question, but did you change the filter when you changed the oil? If not, the filter element would be gas soaked which would pollute the new oil, making it smell like gas. Has the oil level increased in the sight glass since you changed it last?

It's also possible that the float is sticking open in one or more carbs. I just had this issue when I was wet setting the floats on my maxim x. Pull the carbs and set it up like you're wet setting the floats. Hook up the gas line and fill the bowls. The offending carb/carbs should reveal itself.

 

I will need to carefully monitor the oil level in a controlled position and temp. If the oil level is not changing then I imagine I am OK? But then why would the case breather fumes smell like fuel?

 

yes I did change the oil filter. But I don't think the oil level is going up. Maybe it's just the smell happening. It's throughout the oil and blowing out the crank case exhaust. It's enough to cause worry but if oil is maintaining level then I'm OK right?

 

Are you sure that you are not smelling blowby gasses?
Have you done a compression/leakdown test?

It is highly unlikely that you are draining gas into the crankcase while the bike is running. This would result in wet, black fouled plugs.

Ghost

 

Did you smell the old oil after you drained it, and away from the bike?

If you have a milk jug of oil that smells like gas smells then its a problem.

 

It is very possible this is fume gasses getting by old rings. I suspect the rings being as old as it is aint so tight. If that is the case then I suppose I'm gonna survive for now. I think the oil level is the thing to watch here. If it's not going up then there is not likely gas building in the case.......right?

 

How about this, the level stays the same, you're burning oil & it's being replaced by gas.

 

Haha the possibilities are endless. Well the exhaust is not smoking. Plugs look good. Maybe lean a tic if anything.

 

my "haha" is me laughing instead of yelling! Just one problem after another to solve on this bike and just like the carbs, this problem is super hard to pinpoint. If I am getting fuel into the case then the oil should get pretty much watery right? Would it change color? I wonder if you can put color addative to the fuel to test for this?

 

I would say you are right about the oil level not changing for the most part. Just depends how much is being dumped though. As for your tank, if it doesn't seem like it is leaking with the tank off the bike (or feed line not hooked to the carbs) then you can eliminate the tank as possibility. With regards to the tank, has it ever been cleaned out? A lot of people clean out the carbs but neglect the tank. Which just ends up fowling the carbs again. I always use a clear gravity type inline fuel filter as a precaution, since I can never get the tank 100% clean.

 

Yes I do have a new pepcock rebuild and a clear inline fuel filter. The tank is not leaking at all in the ON position and hose disconnected from carb.

 

Rode my bike fpr part of the day. All the while concerned that I could be killing the motor "IF" in fact gas is mixing into the oil. But, the oil level is not rising. Gas like smells are vaporizing out of the crank case and quite visible once the engine warms up. Then stops immediately when the engine is turned off. Engine sounds great and no real problems seem to be occurring so I am left to guess what's happening. I am thinking it could be gases getting past old rings and the smells are mixing into the oil.

 

Did you ever find out what happened?