leaking gasoline on 1978 r80/7

[jaapovergaag]

Hi,

rode my broher's r80/7 yesterday. All of a sudden on the left side, gasoline was dripping out at a high rate. It dripped at the bottom of the carburator. Shut both fuelvalves off and it stopped. Gasoline is dripped while bike is running and when it is shut off. The fuel lines from the fuel valve until the carburator is dry.

Any ideas?

Jaap Overgaag
1986 r1100rt
1978 r80/7 (my brother's)

[Bob_M]

If the bike has not been ridden in a long time, or if it is old, the float bowl gasket can dry, harden or just stop working. Hopefully this is a simple fix. Cork gasket a couple of bucks, labor 3 minutes.

[donbmw]

Your fuel lines could be fuel soaked and need to be changed. Some of the fuel line that you can get will go bad over time from the fuel being in it.

Don

[FrankT]

If it is dripping out the small hole on the bottom of the float bowl, that is the overflow tube outlet from the float bowl. The most likely suspect is a sticking/worn float needle or small debris in that area preventing the float needle to seat and shutting off fuel supply to the bowl. While you are at it, replace the fuel line if it's old.

[James.A]

All early airheads that have not had new floats and needles need 'em. Your best bet is ro re-new everything that is releveant. While your'e at it, spend $10 for the Bing book. You won't be sorry.

[RandyB]

http://www.webbikeworld.com/bing-carburetor/

Well worth the $8 and change.

[Dylan76]

If it is dripping out the small hole on the bottom of the float bowl, that is the overflow tube outlet from the float bowl. The most likely suspect is a sticking/worn float needle or small debris in that area preventing the float needle to seat and shutting off fuel supply to the bowl. While you are at it, replace the fuel line if it's old.

Remove clip and take off the bowl. Spray everything down with carb cleaner and gently work the float and valve. Clean out bowl and replace. Hopefully this will get you running again. Very simple and the first thing to try.

[pmdave]

It's possible that all you have is a piece of debris in the inlet ("float") valve, and blowing it out will cure the problem. Temporarily. It helps to have inline fuel filters close to the carbs. The transparent variety allow you to see what sort of gunk is sliding downhill.

If the fuel lines are shedding bits of rubber, the problem will soon reoccur. If the fuel lines are braided on the outside (stock BMW) but older than 4 or 5 years, it's time to renew them. You can either use the same braided rubber hose, or go to the expensive snowmobile fuel line (typically blue translucent) that always stays flexible and never seems to disintegrate.

It is not unknown for the tiny brass overflow tube in the float bowl to crack, allowing fuel to dribble out the bottom even if everything else is OK. The fix is to replace the float bowl.

The old Bing carbs have plastic foam floats that gradually disintegrate and soak up gasoline (especially gas laced with alcohol). A soaked float sinks lower, allowing the fuel level to rise to the overflow--not to mention allowing the engine to run rich and maybe even allowing a cylinder to fill with gas while parked. Consider replacing the floats and valves and resetting the level. The more permanent (but outrageously expensive) fix is to replace the floats and bowls with the "alchohol proof" versions from the Bing man.

Time to get your hands dirty. Remember: gas is dangerous stuff.

pmdave