reading plugs

[1034am]

Hello, I finally got my 'project' bike running, still not ready for the road, but it starts right up when cold. (valve adjust, carb rebuild, new rectifier, tune-up)
I decided to pull the plugs to see if they were the same, and they were not. The right side is med-gray, looks like a used plug. The left side looks almost brand new. There's a little gray soot, but it looks a lot different than the right side. While it was idling I felt the exhaust and the right side was normal burning hot, left side was significantly less. (Left side did have spark when I checked it.)
Without the advantage of a test ride, are these results pointing to something specific? I've read possibly fuel mixture, or carb synch.

Thoughts?

[Big Rich]

If you have spark and compression (good on you for doing the valves, but did you actually test compression?), then I'd look at fuel delivery.

You can do a bench sync if the carbs are off - just need to know the butterfly valves are as close as possible. But if all the bike did was idle, you were only running off the pilot / choke circuits so I'd make double sure those are clean as possible. Either that, or the fuel level is so low on the left carb that there's nothing making its way into the intake.

[1034am]

What would cause 'low fuel' on the left side? A bad float?
I can do a compression test over the weekend.

thx.

[Big Rich]

If the float got caught on the bowl gasket, sticking float needle, that tang for adjusting the float needle is bent out of whack, or an actual blockage in the fuel line to the left carb can all cause low fuel issues.

But check the float height with a clear tube before anything. That will tell you if it's a float height issue or a dirty carb circuit.

[1034am]

Ok, thanks. I'll check the float height to see where it's at.
Regarding the compression check, is there a preferred method of shutting off the ignition, or is grounding the plugs/wires the way to go?

Thx.

[Big Rich]

All you have to do is remove both spark plugs, leaving the plug boots hanging around. Just make sure you're holding the throttle wide open when you hit the starter - only takes a couple revolutions to get a max psi reading.

[1034am]

Ok, some of the online instructions indicated unplugging the 'ignition system' so nothing gets fried. I was thinking of unplugging the rectifier, but I can just ground the plugs.

Anyway, the float was way off. Thanks for the tip. It was below the bottom of the carb. And while checking, I cracked the fuel bowl outlet when I attempted to close the valve. New fuel float, and if I can find one, new fuel bowl before much else gets done.

One step forward, two steps backward....

Thank you for the assistance.