[backfiring w new pointless distributor]

I recently had old distributor replaced with electronic pointless distributor on my R-1. Plugs and wires were also replaced. Engine runs beautifully EXCEPT I get backfiring (popping sound) between 2,500-3,000 rpms on decelleration/coasting from that rpm range. This was NOT present with old distributor. Any thoughts on what is wrong?

[Intro and Question]

I have a '63 R1 with electric windows. It appears as though i have to replace the motors (ok going down, slow or no go going up). I have the Avanti Mag article that describes one way to get the motor out of the door. Does anyone have any better ideas? Does anyone have a write-up of this procedure? I would appreciate any hints.

p.s. I will take pictures when I do it for future reference.