Backfire/popping when I let off and dead spots in throttle

[newell]

I have been toying with my 79 for a while now, lately I have been getting a backfire/pop when I let off and I have had the carbs off and cleaned them twice this summer... I run a two into one exhaust with stock needles and jets. I had the right side carb back out of the boot the other day and am wondering what would cause that and the backfire (sounds like a gun shot) on the deceleration. Thanks

 

[5twins]

Check for air leaks. If you find none then I would re-jet and check the timing. If the timing is off just a little, you can blow carbs out of their mounts like that - been there, done that, lol.

 

[newell]

Thanks for the knowledge

 

[Ironsled77]

you can blow carbs out of their mounts like that - been there, done that, lol.

Sounds scary! Never seen that before.

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[grizld1]

Newell, you can't fix ignition grief through the carburetors. As 5twins says, what you describe is typical of ignition trouble, and it's particularly a symptom of a defective automatic timing unit. Check your timing in both advance and retarded modes. If it's too far retarded at idle when dialed in correctly at full advance, replace the ATU. If you want to try correcting the curve, don't tamper with the tabs on the ATU rotor; remove the bob weights, clamp them tight in a padded vise, and peen the tips until they spread out to a width of .160". Clean up any rough spots with a fine file and 600 paper.