Gas in oil

[Guest]

First off, I'd like to thank everyone on this site for the useful information you've provided me in working on my bike. I have a 1980 550L that when I purchased would run fine for 10-15 minutes and then die. It would not start again until it had cooled down. In chasing this problem, I have done a lot of the recommendations from this site: carbs cleaned correctly with new o-rings, new boots, new petcock, and valve clearances adjusted. With all of this done, the problem stayed the same so I came to the conclusion it was something electrical (what I am least familiar with) that was being affected by the engine being warm.

This was all done last year and I let it sit for a few months during the winter. After starting it up for the first time this year, It started and after a few minutes I revved it a couple times. With this, gas started pouring out of the airbox. I did a little research on here and figured it was the floats sticking. I pulled the carbs off and replaced the float needles (which I had not replaced when I originally cleaned the carbs). I re-checked the float heights (it has the step-down floats) and found that I had accidentally verified the height of them at the top instead of the stepped down part. I adjusted the heights and then put the carbs back on for it to still do the same thing. By chance I thought maybe the gas was coming through the breather hose instead of the carbs and sure enough it was. I ran it with the breather hose free and a gas/oil mix poured out of it. This got me to smell my oil which reeked of gas. Up until this point, I had not changed my oil as I figured I would change it when it was road worthy so I do not know when the PO changed it last. Last night I pulled the oil drain plug and a gas/oil mix sprayed out. 10-11 quarts came out and it had the consistency of straight gas. I am thinking this could be bad piston rings? Is there a way this could be something with the carbs? I put fresh oil in it and figured I would see how fast the gas is getting back into the oil.

[tom203]

Since this is 1980, was your new petcock a lever less version? Is so, do you understand the prime position on it? If it's another style petcock, please describe...

[Gorminrider]

Up until this point, I had not changed my oil

given you put a new fuel tap on and much more without knowing what the oil was like or it's level! (=a pretty good clue that gas is getting in), it is hard to know if there is still a problem. I get that you can't comment on the original problem

run fine for 10-15 minutes and then die

until this new one is solved...sooo if your (finally!) changed oil gets polluted again, the fuel tap is still the first thing to check, new or not.
Be sure to observe the tank and attached tap on the bench. No drips unless turned to prime.
Be sure to suck'nblow into that vacuum activation pipe and thereby test it before hooking up the fuel to the carbs.
Be sure you have the vacuum-activation pipe attached at the right places.
Be sure it is NOT set to prime when running or stopped...this shouldn't matter but is good practise,IMO. it's only for starting a dry bike after the season...or a dropped bike too, I guess.
and then:

and replaced the float needles

and seats? how about the seats-the needles seal against the seats. ...messing with the assembled carb should include the simplest tests of the float inlet mechanism =turning the carbs upside down and blowing into the gas inlet =no go....flipping them upright and they should clear.
This isn't a guarantee of perfect performance, but can be refined by attaching fuel to the (level)carbs on a bench and observation of any overflow into the bore of the carbs. the which you can do right now without removing the carbs. Looking in with a small mirror from the airbox perhaps...
If you can say that the bike passes these simple tests, it would help pin down what's going on.

[Jake550]

Yes, the new petcock is the lever-less kind. I have been assuming that the arrow at the top is "on" and angling it to the left to "Pri" is having it on prime. Was i correct in this assumption or should i have it horizontal with the two dots for it to be in the "on" position?

I replaced the float needles and not the seats because I was thinking there was a possibility that the springs inside the old needles had broken down when I put them in the carb dip. The old needles seemed to be in good condition. I installed the new ones just to be safe.

[tom203]

"should i have it horizontal with the two dots for it to be in the "on" "

I think this is the "on" position, while vertical is the "pr" . But wait for someone to correct me as I've never had this style (and plan to avoid it)
best to replace those old o-rings/gaskets on needle seats- they probably don't seal well after 35 years whereas the needle could be fine.

[gustovh]

Horizontal is on.

V

[Cyrano]

Here's how your fuel tap works.

[Jake550]

Thanks for the help with that. I have it back to the horizontal 'on' position and have changed the oil again. Even though the petcock was on prime, should I be worried that almost 10 quarts of gas made it through the engine to the oil? Could this still be bad rings?

As for the original problem, I am going to start checking the electrical components. When I click on a link to the stator papers, I get an error. Is there a new link somewhere or does someone have a pdf copy of this?

[megatwin]

Rings,even on a brand new engine,don't make a liquid tight seal.Gas is very thin.