I just swapped out the chopper air filter for the stock S&S. It's been raining up here in northern Cal so no test results from the switch. I'll keep you all posted. I'm also betting this change will make a difference.

 

Wouldn't hurt to do a compression check either. Low compression makes for hard starting and poor combustion...

 

I never liked Champion plugs they seem to foul in my bike. When you put on the air cleaner did you have a passage for the fuel bowl vent, or did you take out the allen set screw? I've been running a stock model air cleaner on my E model and I had to make a spacer for it to fit. Made the passage in the spacer and drilled a hole in the cleaner back plate for it. With that passage not open it would run rich.

 

one thing that hasn't been talked about yet is ign timing. Make sure it's DEAD on, with a timing light. when i rebuilt my last winter, i kept fouling plugs and got a skip/stutter at idle. i bumped up the compression during the rebuild and upgraded to electronic ign. had a little ping on accel, so retarded the spark a hair. this was my issue. retimed it dead on, skip/stutter and fouling went away, but ping was back. so i had to resprocket the final drive back to stock and have had no isssues since.

shovels are really picky about ign timing. and a S&S carb on an 80" shovel should be running a .295 idle jet and a 72 main, this is a little on the rich side, but dialed in with the idle mixture and accel pump should not foul plugs and run a little cooler. and btw, champion are junk. use stock hd, autolite or bosch.