GS450S firing on one cylinder

[doggscube]

Timeline of the problem:

1. Petcock failed, started leaking gas into the LH carb. Pulled and emptied tank.
2. Bike sat for week waiting on new petcock.
3. Petcock installed, started on one cylinder
4. Pulled plugs and cranked engine to clear combustion chambers.
5. Cleaned LH spark plug.

What's the next step?

Thanks,
Jeff

[chef1366]

Did you try a new plug?

[doggscube]

No, I didn't. Would swapping the plugs diagnose a plug problem? I don't have extra plugs, and the plug appears to be fine.

I went through this process before, except I rebuilt the petcock. It worked fine after the above steps.

Jeff

[SPARKSS]

Swapping your plugs wouldn't be a bad part of your troubleshooting. You said you cleaned the plug.......what did you do there? Can you confirm that you have spark voltage at the dead cylinder at this time? If you have spark voltage and by swapping or cleaning determine that the cleaned plug is able to fire, then you might either check compression in that cylinder or just squirt a little engine oil down the plug hole before reinstalling which often helps a cylinder, washed down with gasoline, reseal to the rings (regains compression).....this may or may not be a temporary problem.

That is where I'd be, based on what you wrote

[doggscube]

I verified spark.

Swapping the plugs shows that it's the cylinder, not the plug. I do not have the means to do a compression test. I'll try the oil in the cylinder idea. The bike ran well before.

ETA: the oil did the trick. Thanks!

Jeff