Fuel in crankcase?? What's happened?

[KapitalKat]

Just bought a 1/1983 GSX250 twin in really good nick but has fuel mixed in with the oil in the crankcase. Bit of a mystery to me has anyone got any idea what is causing this. Talking about a lot of fuel here, as seems to be running freely from the tank. Any help would be appreciated.

[bikechump]

your float level could be incorrect and not allow the needle to close on the seat and let fuel down past your rings. It could also be a faulty petcock allowing fuel to pass down the vacuum line to your carbs. (result the same)

i would check the petcock first and if that isnt at fault your going to have to rip those carbs apart. when looking at the needle check for any pitting or ridges and clean the seat with a q-tip. (remove the seat entirely and check the o-ring. it could be at fault as well.


if none of those work post again
good luck

[feelergaugephil]

Put an inline fuel stop/switch on the main fuel feed to the carbs, put it in the OFF position when you dont use the bike, you'll never have the gas in the engine problem again.

[rphillips]

For this to happen, both the petcock, & a needle & seat must be bad. If the petcock is bad, the properly working needle & seats will stop the gas flow. If the needle & seats are leaking, a properly working petcock will prevent the problem. You can rig the problem with an in line fuel valve, & it will work fine, or you can fix it. Whatever is best for you.

[bwringer]

The needles and seats in most GS models are not designed or able to hold back gasoline while the bike is parked for long periods.

While you may get away with leaving the petcock on prime (or having a bad petcock) over a long lunch or a day at work, gas can work its way past the float needles over a couple of days, even if the float needles and o-rings are in perfect condition.

Your first priority is to replace the petcock. Then, if it overflows when it's running, then you may have bad needle seat o-rings. You can get new ones at any Suzuki dealer, or get enough o-rings for two complete rebuilds from Robert.

http://cycleorings.com/

The inline fuel valve is just a workaround -- replace the petcock ASAP.

[SqDancerLynn1]

Most problems with the BS carbs are caused by a bad petcock & bad O rings on the needle seat !!!!

[Surly]

I'll be doing all that this week!

I ended up with gas in the airbox. I think I was spared the gas in the engine. I found an NOS petcock on ebay for a great deal and I'll be changing that out this week. Pulled the carbs (again) and am going to pull the bowls and clean the needles and seats (less than a year old) with q-tips. Throw it together and try again.

Best of luck to you.

[t3rmin]

Just had a similar problem. Gad pouring out of the airbox drain tube. Dismounted the carbs, pulled the bowls/floats/valves, cleaned them (I thought), put 'em back on, same thing. Narrowed it down to the outside left carb, took off the bowl with carbs still on the bike, pulled out the needle, and lo-and-behold, a big chunk of debris fell out. Musta missed it 'cause I didn't take the little metal screens of the needle seats -- thank you, gravity! Put it back together, and no worries!

[rphillips]

Don't just think the "O" rings are probably all right, I'd give it a 50/50 chance needle & seat or "O" ring.

[jeff.saunders]

For this to happen, both the petcock, & a needle & seat must be bad. If the petcock is bad, the properly working needle & seats will stop the gas flow. If the needle & seats are leaking, a properly working petcock will prevent the problem. You can rig the problem with an in line fuel valve, & it will work fine, or you can fix it. Whatever is best for you.

Not true - if the vacuum diaphragm starts to leak, then fuel runs down the VACUUM hose into the carbs high up on the body - this fuel then makes it's way down into the combustion chamber washing the cylinder clean of oil, and down into the pan where it dilutes the oil - often to the point of a catastrophic failure.

It's not so bad in the roller crank engines, but a plain bearing engine can die very quickly if this happens.

I'm not a fan of vacuum petcocks one bit - especially the way the vacuum takeoff is positioned on most carbs.

[tconroy]

If the petcock checks out fine then it's your 0-rings in the needle valve seats.Also check the float height while your there.