GS1000G #2 Missing-Ideas?

[Guest]

I finally have my 1980 GS1000g running, however #2 is dead. The bike is idling and revving well aside from missing. I have fire to the plug but it soaks with gasoline.
Here's the stats;

1085 wiseco kit in fresh bores
Fresh head work
Bs34 CV Carbs, Freshly cleaned
Mixture screws at 2.5 turns
137.5 Mains
47.5 Pilots
5D57 Needles in stock positions
Floats 22.5mm
Pod filters
New intake manifolds and clamps
Accel coils and wires
Dyna S


pulling the plug made no difference
I swapped and cleaned plugs, no difference
I did a fire test with the plug out of the engine; spark is very strong
Compression is a bit low at 120, but even across the four cylinders.
Checked for vacuum leaks, good there

My thought is to check float level, fuel flow to the carb...
Any other ideas?

[tkent02]

Your petcock diaphragm is probably leaking fuel down the vacuum line. It connects to #2, and that's a very common problem. It dumps fuel right into the carburetor bore after the venturi, goes straight into the intake port. Pull the vacuum line off the #2 carb, if any fuel at all comes out that's the problem, it should be bone dry in that line.

[Big T]

Put a vacuum cap where the vacuum hose goes on #2 carb
Turn petcock to prime and run it

If that cures the misfire, get a new petcock

You may have a petcock without a prime position. If so, connect a remote fuel tank

[Izukes]

I'll try it, but not sure. I have a new aftermarket petcock. I tried pulling the vacuum line off today. I got no fuel through it and it made little difference in the way the engine ran. The plug is wet and the piston looks too clean through the plug hole. It could have washed down the cylinder. I'm going to try putting a little oil in the cylinder as well....

[tom203]

Go deeper......Get some clear tubing and stick on petcock vacuum fitting and suck on opposite end- any gas headed your way? If no, then it's a carb #2 problem.

[Katarat]

Plugged pilot jet

[Izukes]

Possibly. I checked the petcock today by plugging the vacuum port on #2. No fuel through the petcock vacuum line nor any change in running. I'll take the carbs off tomorrow and check pilot jet passage; however I just cleaned the carbs and installed new pilots and mains...

[hjfisk]

Check your needle and seat , float height

[jdvorchak]

When you rebuilt the carbs did you change the o-ring on the needle seat? If not fuel can leak around and flood even though the needle is seating and set correctly.