Cylinder 3 still not working?

[Guest]

All carb passages were clear and we have been through them/soaked and they were checked again when rejetted. However because I have been through the carbs many times and still have not figured out I may just start over with a new one. I have been looking on Ebay but can only find a set of 4. I'm not going to build my own from carb body because it could be a screwy part. The carb was injecting gas however the bike would not backfire? I figured I would see at least a little fire out of the pipe. There was gas leaking out of the pipe? We did make sure that the bowl was not overflowing but even if it was I would expect the occational backfire?

Post in the wanted parts forums here. There are many guys with lot's of spare parts.

-Dave

[DerekofMaldon]

GS1000 #3 cylinder Wet/Not firing

I know this is a late post. But maybe it will help those searching the archives.
If the#3 cylinder is not firing, no spark, Wet plug, Heavy smell of gas at the tail pipe.
CHECK THIS NEXT. THE PETCOCK DIAPHRAM!
The fuel valve/petcock is operated by vacuum connected to the #3 intake. The diaphram has failed and raw fuel is being drawn straight to the cylinder. A failed petcock diaphram will allow gas to run to the #3 intake even with the engine off. fuel will get in the cylinder and can at the very
least seep into the crank case, diluting the oil. At worst the combustion chamber may hold enough fuel to fill and bend a rod if the other cylinders fire on the first attempt. causing major crank/rod/engine damage.

Took me a long time to figure this one out. The diaphram only cost $9.Took the carbs off and rebuilt them twice. I took the head off thinking I had broken valves or hole in the piston. Finally picking up the fuel tank to re-install it and fuel was leaking out of the vacuum line onto the garage floor.

Good Luck.

[tom203]

I know this is a late post. But maybe it will help those searching the archives.
If the#3 cylinder is not firing, no spark, Wet plug, Heavy smell of gas at the tail pipe.
CHECK THIS NEXT. THE PETCOCK DIAPHRAM!

Took me a long time to figure this one out. The diaphram only cost $9.Took the carbs off and rebuilt them twice. I took the head off thinking I had broken valves or hole in the piston. Finally picking up the fuel tank to re-install it and fuel was leaking out of the vacuum line onto the garage floor.

Good Luck.

If you had found this site earlier (and found the common petcock problem), you would have missed all the experience you got pulling the carbs! But please note that CV carbs tend to get their vacuum off #2 carb, while the older VM got it off #3. That assumes that #4 carb is under your throttle hand.
Diaphram for $9 ???? I'm tempted to try fixing mine, despite all that I've read here- I must be feverish!

[Big T]

I know this is a late post. But maybe it will help those searching the archives.
If the#3 cylinder is not firing, no spark, Wet plug, Heavy smell of gas at the tail pipe.
CHECK THIS NEXT. THE PETCOCK DIAPHRAM!
The fuel valve/petcock is operated by vacuum connected to the #3 intake. The diaphram has failed and raw fuel is being drawn straight to the cylinder. A failed petcock diaphram will allow gas to run to the #3 intake even with the engine off. fuel will get in the cylinder and can at the very
least seep into the crank case, diluting the oil. At worst the combustion chamber may hold enough fuel to fill and bend a rod if the other cylinders fire on the first attempt. causing major crank/rod/engine damage.

Took me a long time to figure this one out. The diaphram only cost $9.Took the carbs off and rebuilt them twice. I took the head off thinking I had broken valves or hole in the piston. Finally picking up the fuel tank to re-install it and fuel was leaking out of the vacuum line onto the garage floor.

Good Luck.

Wrong carbs, BS series vacuum is on carb #2