Backfire #2 Carb

[Guest]

I have been working on my 81 1000L fixing the regular issues with the bike.

However I have an issue with a backfire into the #2 carb, the one with the vacuum line to the petcock. I noticed it was backfiring into the carb as I can see fire when I look into the vacuum port. It isn't all the time, happens every few minutes.

There is an cracking sound when it happens and the carbtune spark plug flashes from blue to white when it happens.

What am I looking at here, burnt valve, tight shim? Am I on the right track?

[tom203]

I have been working on my 81 1000L fixing the regular issues with the bike.

However I have an issue with a backfire into the #2 carb, the one with the vacuum line to the petcock. I noticed it was backfiring into the carb as I can see fire when I look into the vacuum port.

You can look into vacuum port? so vac line is off and air is sucking in here causing a lean mixture?

[TheCafeKid]

You're probably looking at an air leak, or youve got a pilot jet or passage partially plugged up with gunk still.

Have you adjusted the valves, and replaced the intake boot rings? Also have you sealed your airbox properly? Checked the vacuum line for cracks or a hole?

[jhillier449]

Intake boot o rings replaced, air box sealed, carbs rebuilt.

I guess the valve adjustment is next.

Thanks for the tips.

cheers

john