A/F Adjustment Questions

[ricko]

After re-rebuilding my carbs that have been sitting over 16 years, I got the bike running well. The only issue is some popping during slightly choked warm up. The A/Fs are 3 turns out now, can getting them dialed in correct the backfiring? Is the proceedure to screw each in till idle suffers and then out till it gets rough again and put them in between those spots? It has a Stage1 kit and no Vboost. Does that make a difference in adjusting the A/Fs since each cylinder is always drawing from 2 carbs? Does adjusting these change the sync? And finally, how can you tell which cylinder is the culprit with a 4-1 pipe?

 

[maleko89]

It's next to impossible dialing in sync or a/f screws w/o vboost. I'd close it if it's still installed and get them dialed in. Some popping is normal with choke/warm-up. Only set sync and a/f screws with bike warmed up.

 

[ricko]

Thanks, the Vboost is long gone, just straight tubes. I kind of thought that was going to be the answer. I thought about plugging the passage to adjust and then opening it back up, but it's really ridable now and I'm tired of taking the carbs off and putting them on. It would be the same issue if I took it somewhere to have the o2 read wouldn't it?

 

[maleko89]

Yeah, a plug would work ok assuming it's a tight seal. An O2 meter would work I would think. You would have to go back and forth between each side to determine if the off reading is due to carb #1 or #2, for example. To sync, you can get a Weber carb tune as that reads by sticking it in the intake of each carb.