Right Exhaust Fart

[mixelpix]

Howdy,

1980 LG, when I am in second and revving up around 6k and close the throttle leaving the clutch engaged, I get a back fire out the right exhaust - not the carb. I am assuming this prolly is indicating that the carbs need a little balancing? No farting when I do the same /and/ pull in the clutch.

Any sugs would be appreciated.

Otherwise she's got 38K, the PO was the 2nd owner and had a valve job done recently. Otherwise she's got even compression and is in great shape - notwithstanding a lil oil leak from the cam chain tensioner. But I'm getting to that one soon enough...

Thanks!
-Patrick Kennedy

[TopCatGr58]

Hey there Patrick,

Somebody explained a while back about backfires, and how since the coils fire a waste spark during the Exhaust cycle of the entire cycle that IF there's unburnt fuel getting into the exhaust, then when the spark fires, it can ignite that unburnt fuel and POP/POW....backfire! So....I would think you're on the right track in needing to check out the carbs. However, you might also need to recheck the valve clearances to make sure that they aren't too tight, allowing incomplete combustion or leakage. And do a cam chain slack adjustment as well, if not been done in a while!

With the clutch engaged, the rear wheel is spinning the engine so to speak when you close the throttle, but there's a variance in the vacuum signal going to the timing plate, so it may be turning more or less than needed as well? You may want to check it for free movement, no vacuum leaks on vacuum hose, and that the vacuum unit is holding vacuum. And you may want to verify timing with a light!?

Also, are you sure there's no exhaust gasket leak? Good Luck!
T.C.

[mixelpix]

Thanks for the insight!

Great tips TC!

[Dragonrider]

Also, check for air leaks into your exhaust. There is always unburnt fuel at rpm when you chop the throttle, particularly if you are decelerating against the engine.

Air leaks into the exhaust will allow/help it to ignite...pop!