Friday, November 16, 2007
I have been having a problem with fuel leaking out of the overflow tubes on the carburetors for some time now. I figured that it was simply some dirt in the float needle and it would eventually work it's self out. Unfortunately it didn't and it was getting worse. I tried the simple, quick fix where you spray carburetor cleaner in the drain screw hole and tap on the outside of the float bowl in an attempt to dislodge the dirt from the float needle path. Well, that didn't work either.
The Float Bowls on the Mikuni Carburetors on the 1982 Yamaha XZ550 Vision are accessible while the carburetors are still mounted on the bike. The tops of the carburetors come off with the floats attached to the top of the carburetor. When I disassembled the carburetors, I found that the rubber O-ring on the jet above the float needle had shrunk considerably. Fuel was simply bypassing the jet, float, needle all together and over filling the float bowl.
It's good to have spare parts! I took apart another set of carburetors I had and found brand new jets in my spare carburetor! It appears that someone tried to rebuild this set of carburetors and quit. A quick check to see that the jets are all the same size... A quick swap and everything was put back together. Fired the bike up and blammo, no fuel leaking anymore. Problem solved and I didn't even have to re-synchronize the carburetors.
Next Fix: Shift Shaft Seal Leak (I've done it before, don't want to take the side cover off again to do it. Procrastinating...)