Died, restarted with white to gray smoke

[Jerry]

Leaking petcocks do not cause carb flooding. At best, when shut off they can make the best of a bad situation. Problem is in the carbs, particularly the needles and seats. They are leaking when they are supposed to shut off gas into the carb(s). The vacuum operation was designed as a safety feature, preventing gas from flowing if the bike was not running, as in an accident or tip-over.

Fixing the petcocks is always a good idea, but it will not stop the carb flooding problem; if the fuel level in the carbs cannot be kept at spec your bike will run poorly. Do the carb work needed, replace the inlet needles and seats, and your cabs won't flood even if you leave the petcocks on all the time.

[skids]

You know what? I'll bet someone was rebuilding putcocks and got the handles imxed up on reassembly!

Originally posted by wildbill
Gas should only flow when on PRI.Some of these petcocks operate backwards,the one that looked like it was on RES might have been on PRI instead.I have had petcocks where to turn to RES,you would turn the left one one way and the other{right}the other way.It is easy to get mixed up.Check the petcocks again because gas should not flow freely when on RES.Good luck.

[Hepcat]

I've got an XJ too, and I'm not sure if my petcocks got swapped (left for right) but mine are off when pointed forward, Prime is to the rear, and on and reserve are up and down, respectively.

One thing I noticed about my petcocks that I haven't seen mentioned here is that the prime runs out of one spigot and on and reserve run out of the other. Prime should bypass the octopus whose function is (correct me if I've misinterpreted this here) to shut off flow of gas to the carbs when the engine is not running. If the left and right got swapped and the plates with the positions on them did too, it's entirely possible that the hoses are hooked up to the wrong spigots and prime travels through the octopus and on/res bypasses it. This would allow for gas to run unrestricted past the octopus when the bike was off, but the valve was on/res. The carbs then could overflow if the fuel valve was not seating properly. So check to be sure the fuel line going directly to the octopus is hooked up to the spigot that allows fuel through when in the on/res position.

I took my petcocks apart because they leaked fuel when in the off position. I flipped them over because the friction of turning the lever was tearing the edges of the holes and I wasn't getting a good seal after I turned the valve. When you flip them over, the other side, which was in good shape on mine, takes the wear and tear but is ok because it doesn't have the torn edges to flop over and weep fuel.

Hope that helps some...YMMV

[raul]

[QUOTE]Originally posted by Jerry
[B]Leaking petcocks do not cause carb flooding.

I have to disagree on that, since my exSF bled gas from the airbox and replacing petcock gasket cured the problem. The gas problem was so bad, the airbox was constantly overflooded, dripping on top of the engine. Be careful if that happens - it actually melted/disintegrated one of the rubber joints connecting the carb to the airbox not to speak of the foam(?) seal. I had to replace the whole airbox. I tried to cure by manufacturing new petcock seals - the ones with 4 holes, from different materials - using even Dr. Martens soles :-) and making the spring stronger. Good for one day. After I replaced with new petcocks - the problem went away.

----

I had a similar problem - engine dying on first run with my newly bought SH. Some dripped fuel as well, but not from the airbox. The bike had been sitting for 6 months with no gas in the tank. The battery was dead empty, charged it for 15 minutes and took off. I ended on the side of the road cause the bike would die no matter how much revved - kind of in a cyclical motion. All hope gone, my friend gave me a push and it started up again - I kept revs up and got back. After recharge it however cured the problem - although I have only driven one day since. The idle scew was way off mark as well...

[nashville_bill]

I think the point is that a leaking petcock can not cause leaking gas from the carbs by itself. If all four of the float valves are shutting the gas off then it doesn't matter if the petcocks shut it off or not. Of course, you want ALL of them to work.