fuel leak at crankcase drain hose

[Dougr]

I have a 1981 CB650 it has just started to leak gas from the crankcase breather systems drain hose when parked after a ride after it has cooled down. Any body have any ideas?

[GeorgeSweety]

I have a 1981 CB650 it has just started to leak gas from the crankcase breather systems drain hose when parked after a ride after it has cooled down. Any body have any ideas?

If I understand your post correctly it sounds like one or more of your carbs could be flooding, have you got CV or PD slide carbs? If you have CV carbs it could be your vacuum fuel off valve gone bad.

[GeorgeSweety]

Try removing your side cover and air filter and check for fuel inside your air box.

[Dougr]

I do have the CV style Carbs. was no fuel this morn in the air box just a oily residue no external leaking at carbs. rode it yesterday in cool foggy weather stopped for coffee about 1 hr. forgot to shut off petcock and there was a puddle of fuel under the bike was dripping from that drain hose. also the autoshut off valve has been removed due to leaking

[GeorgeSweety]

If you see fuel dripping again then try tapping your float bowls with a screwdriver handle one at a time to see if it is a sticking float. You may be able to work out which carb it could be (if it is a sticking float) by seeing if a quick tap stops the drip. Its always a good idea to switch the fuel tap off on these old bikes just in case.