Would Someone Explain This One To Me

[OldVet66]

I have been having trouble with my right two carburetors for a while. First of all number 3 would not fire, so I rebuilt and synced the carburetors the winter before last. It ran perfectly and showed me that I had finally learned how to dial it in. Shortly after the spring riding season began My RA started flaring up again and I did not get to ride much at all. The bike sat for quite a while, ridden once in a while on good days and last winter number 3 started working sporadically again. This spring number 4 went cold so I decided to rebuild again and also replace the float seats and needles. When I went to drain the tank I found the petcock would not flow on prime, only with vacuum. That was fun, I don't have a vacuum pump. I ordered a new petcock from Z1, a KL part number. I just replaced the petcock (the dreaded '80 petcock) put fuel in the tank after being off the bike for several months and it fired up immediately on all four running perfectly. What is up with that! I expected it would not fire up normally. There is a common fuel T. Obviously it was fuel starvation. You would think it would affect all cylinders but 1 & 2 were hot and would idle the bike, 3 & 4 were dead cold. I am thankful that I use StarTron, it kept the carburetors clean through a lot of down time. What are the mechanics of what happened? Buy the way, The KL petcock looks like it came out of the same factory as the Suzuki part I bought for the '80 tank when I put it on the bike. About half the cost of the factory part.

[JTGS850GL]

If the bike was sitting on its side stand, then the carbs on the high side (4 and 3) would drain down first before the ones on the low side (1 and 2).

[2BRacing]

Just a shot in the dark here - Do you leave your bike on the centre stand or sidestand?

If leaning over to the left on sidestand, it may explain why carbs 1 & 2 had fuel while 3 & 4 were dry?

EDIT: Ha, JTGS850GL above typed faster than me!

[OldVet66]

Center stand. That's what I thought the first time.

[JTGS850GL]

Fill it, Prime it and run it. Quit sweating the little things. If she runs fine, once the carbs are all filled then ride and enjoy.

[Steve]

The old petcock MAY have worked on PRIme, it just operates a little differently.

You have to turn the selector to PRIme, then crank the engine so there is at least one 'puff' of vacuum to open the petcock. It will then flow until it runs out or you move the selector.

.

[OldVet66]

That's the way it should work, I know but that is not the way it was working (it had to have constant vacuum on prime and run to flow). That's why I replaced it. It may be repairable but all I hear is that rebuild kits don't work very well. My question is why it didn't affect all 4 cylinders and just two. It doesn't make a lot of sense to me. It runs perfectly with the new petcock. It is the petcock with the little nylon screwdriver slot horizontal for run and vertical for prime. Been riding it, can't believe it purrs so nicely as long as it sat.