787 Backfiring

[TarHeel Challenger]

hey guys


I am helping my father re do his Challenger 1800 (97) and the left motor is back firing and starting hard. It back fires and runs sketchy for a while and we are playing with the throttle to make it run better, and then from 3000 rpm up it runs like a champ, and then you throttle down, and back to sketchy running again. the right motor runs great, and then we had a little issue at low idol.

Could this be a gas issue? Timing issue? I don't know what do next? what do you guys think?

 

[Dr Honda]

a true back fire is caused by a lean condition... but on a 2-stroke, more than a lean run is needed.

if you are getting a pop back out the carbs... I would look at the rotary valve timming... but unless you've had it apart... it shouldn't be able to jump time. It could have excessive clearance though.


Did you clean the carbs yet?