Mystery petrol leak

**mwr09** · #1 4th April 2009

Hi all,

My 2002 XT600E has (another) wierd fault. I was riding home recently and stopped at a junction and thought I could smell petrol. Carried on home, and had a look around the bike. Petrol was literally pouring out of the drain hole on the bottom of the carb all over the starter motor, the same with the engine running and when it was stopped. It only stopped when I turned off the fuel taps. The tube which is supposed to be attached to the drain hole had been missing since getting the bike.

I assumed the drain screw had come loose, but looking at it later it seemed as firmly in there as ever. Started the bike and ran it for a while, no leak in evidence. What's going on?

I've replaced the tube to more safely direct any fuel away from the hot engine should it do it again. However, the drain screw is completely rounded off so I can neither tighten nor remove it. Any tips for getting this out?

I've had the carb in pieces a while ago checking its condition. It all seemed fine, and had been running no problem. Please help!

**djorob** · #2 5th April 2009

Had a similar prob a while back.
Was (Somehow) a blockage stopping the float needle valve closing properly causing the carb to intermittently dump fuel via it's float chamber breather (overflowing).
You've probably thought of this one but a good o'l fasioned carb clean and blow out may help.
Check for wear on the float needle (a worn groove ect).
Removing a worn screw= a nice sharp and small centre punch can be used to carefully persuade a stubborn screw to turn. Use it on the outer edge of the screw head to turn the screw anti clockwise thus loostening it. Get a good purchase (centre punch a nice indent) with the punch on the screw head and change the punche's angle to "knock" the screw round! Works wonders with stuck phillips/posi and other heads.
Dave.

**DAVSATO** · #3 5th April 2009

sounds like someone has hamfistedly overdone the screw, probably with the wrong driver, so that now it wont do up properly or undo. it only needs to be done up barely finger tight with a small electricians screwdriver. some people dont even know there are different sizes of slots, or different types of cross heads. some people shouldnt be allowed out.

you need to get that screw out without damaging the sealing face or thread of the carb body and replace it with a brand new one.

**BlackDogZulu** · #4 5th April 2009

A worn float valve, or something holding it open, would be my first guess. Also, it's not unknown for floats to puncture and cease to float, which gives the same symptoms. The test with the old alloy floats was to take them off and shake them, listening for any fuel inside sloshing around. I don't know if the more modern nylon floats are prone to this. But a float that isn't floating (or where the float height is set too high) would have the effect of flooding the float chamber any time the fuel tap was on. (Or, if the problem is a sticky float valve, any time it feels like it.)

I think a complete dismantle and inspection, and a clean with an airline, is called for.