gas in oil while running???

[eddiev]

Hi to all and thanks again for all the past help.
A few things to ask::

1) Does anyone know if it's possible for gas to get into the oil while the bike is running. And if so what a possible cause would be. I don't think it's the petcock because the fuel line doesn't leak when removed. I'm wondering about the carbs, if a float isn't working right.

2) Also, I don't really follow why a bike left on prime would cause gas in the oil. Wouldn't the floats close the inlet when they're full just as on a bike without vacuum controlled petcock?

3) Can anyone tell me what type of carbs I have on my bike? It is 1982 gs1100gl. The clymer manual is not clear on it.

Thanks again. Welcome to a new riding season and a new bike maintenance season.

Eddie V

 

[Steve]

1) Yes, it's possible, but you would have to have some serious problems for that to happen.

2) Yes, the floats should close the gas off, but sometimes they stick. When you have the combination of leaky petcock and leaky floats, you can end up with gas in the oil.

3) If you have stock carbs, I believe they should be Mikuni BS34 carbs.

.

 

[tkent02]

The VM carbs prior to 1980 had overflow tubes, if the bowls overfilled it ran out onto the road. The EPA mandated these overflow tubes go away, your CV carbs had none, if they overflow the fuel goes into the engine.

Overflow tubes CAN be added to a CV carb.

 

[eddiev]

Thanks for the replies. So the reason fuel gets into the oil on prime is because the floats are not properly closing as they should be. Is that correct? That seems clear to me.

Now, if a float is sticking, what would be happening while the bike is running and not calling for a ton of fuel. Ie: idling etc. I'm just trying to think this out. Where would the extra fuel be going. Just running the bike way rich???. It wouldn't get in the crankcase then right? It would burn in the combustion chamber? Probably badly and run like crap if at all. Correct?

 

[Redman]

..........
So the reason fuel gets into the oil on prime is because the floats are not properly closing as they should be. Is that correct? ..........

The float valve can leak a little and that is not a problem relative to how the engine runs, because even at an idle the engine will use that little bit anyway. So its not a big problem if the floats dont completley shut off. Because that is why there is a petcock, so if the float valves dont completely shut off the petcock does shut off the gas flow to carbs (well, unless you left the petcock in PRIme position).

THe petcock is ment to be a complete shut off, whereas the float valves are meant to regulate the flow to a little bit some times and allow more at other times as required to maintain the level in the bowl.

If the float sticks way open, well, that is a different story, then that is a problem that will effect how the engine runs. Have not had that happen to know first hand. I can, although, tell you what can possibly happen if leave bike parked with the petcock in PRIme position for 5 weeks .... arugh.
.

 

[eddiev]

Thanks a bunch Redman. Great explanation. Bikes with a manual controlled petcock would have the same issue if left in the "on" position then. Is their "on" position the same as our "prime"?

 

[SqDancerLynn1]

My VM's used to **** on the ground when running Until the float valves were replaced. What happens is the rear tire gets very slippery

 

[eddiev]

Thanks again.
Lynn: you mentioned vm carbs and steve: you said I have a mikuni bs34. Is the bs34 a vm or a cv or neither and I'm totally confused?
Thanks.
Eddie V

 

[Redman]

Thanks a bunch Redman. ........... Is their "on" position the same as our "prime"?

Yep, some other bikes (like my Honda Shadow500, and most bike prior to the 80s) have OFF and ON. THe ON being like our PRIme.

.

 

[SqDancerLynn1]

BS34's are CV carbs

 

[nisom512]

oh and Just make sure that you dont run the bike to much with gass in there cause it is "eh not eh so good eh"(in and italian voice)..

 

[Steve]

Thanks again.
Lynn: you mentioned vm carbs and steve: you said I have a mikuni bs34. Is the bs34 a vm or a cv or neither and I'm totally confused?
Thanks.
Eddie V

BS34's are CV carbs

Maybe this will help reduce some of your confusion.

VM and BS are different models of Mikuni carbs. CV is a generic type.

The Mikuni BS series is a CV-type carb.

Many other manufacturers also had CV-type carbs. I have seen in different places that the CV stands for "Constant Vacuum" or "Constant Velocity". Personally, I go with "Velocity", as I have connected a vacuum gauge and seen what happens while riding, the vacuum is NOT constant. CV carbs have a slide that restricts the opening in the carb so that there is enough velocity in the incoming air to properly draw air through the jets. As demand for more air increases, the slide is lifted with vacuum and the opening is increased, eventually allowing full opening.

.

 

[GSJim69]

You can get gas in your oil if one of the cyclinders are not firing. If the fuel-air mixture doesn't burn, gas will get by the rings and into the oil. You would probably notice if a cylinder wasn't firing.
Another possibility would be that it is rich enough that the fuel-air mixture isn't completely burning and some gas is getting by your rings.

Just a couple of possibilities.

 

[eddiev]

Thanks.
I've been feeling the bike is running very hot. What do you think of these plugs? I think the middle two are too hot and am concerned about #1. Kind of smelled like gas. Compression is 120psi and holding in all 4 and bike runs well except for being so hot.
Eddie V

 

[Guest]

Do all the exhaust pipes get hot? If you have a laser heat guage, its easy to tell and be accurate. If not don't touch them but get close enough and you will know if one is cold.

 

[eddiev]

Yeah, they all get hot. A few times when first starting it I would very quickly touch each pipe and see that they heated up evenly and they did. At least for the first 30 seconds.
Thanks.
Eddie V