83 GS1100E backfire(popping) right side exhaust

[chris_rich]

1983 GS1100E
Hello eveyone,

I have read a bunch of posts on this topic but am having a hard time relating anything to the problem that i am having.

This is my first bike which i just purchased this spring, that being said i know very little about motorcycles but am learning as i go. I already had to troubleshoot my charging system and replaced my R/R which solved that problem so i am gaining confidence as i go on.

The problem i am having is my bike backfires through the right side exhaust when starting with the choke on full, after about 60 sec i close the choke. Using the throttle and holding it at about 3000rpm to let the bike warm up it does not backfire. It will also backfire on deceleration.

Checked the plugs and the bike had NGK D8EA, according to my owners manual the standard plugs should be NGK DR8ES-L so i changed them. The old plug on cylinder #3 looks rich(black/sooty) while the rest look a little lean. Is it possible that i have both a rich problem causing the backfire with choke and a lean problem causing backfire on decel or does that even make sense?

What should be my next step?
Valve adjustment
Carb sync
Airbox seals and boots
or maybe all 3

Thanks

[lurch12_2000]

1983 GS1100E
Hello eveyone,

I have read a bunch of posts on this topic but am having a hard time relating anything to the problem that i am having.

This is my first bike which i just purchased this spring, that being said i know very little about motorcycles but am learning as i go. I already had to troubleshoot my charging system and replaced my R/R which solved that problem so i am gaining confidence as i go on.

The problem i am having is my bike backfires through the right side exhaust when starting with the choke on full, after about 60 sec i close the choke. Using the throttle and holding it at about 3000rpm to let the bike warm up it does not backfire. It will also backfire on deceleration.

Checked the plugs and the bike had NGK D8EA, according to my owners manual the standard plugs should be NGK DR8ES-L so i changed them. The old plug on cylinder #3 looks rich(black/sooty) while the rest look a little lean. Is it possible that i have both a rich problem causing the backfire with choke and a lean problem causing backfire on decel or does that even make sense?

What should be my next step?
Valve adjustment
Carb sync
Airbox seals and boots
or maybe all 3

Thanks

You should check the valve adjustments anyway.
Seal up the airbox and then check the intake boot o-rings at the same time since you'll have the tank off to get at the valve adjustment.
Carb synch should be last.
I was amazed that when I replaced the 4 o-rings that were broken and had 1/16" gaps, how much better and quicker the bike warmed up, ran without hesitation, and the backfire/popping was all but eliminated.

[anikmankar]

lean

You are running lean on the 3 or 4 cylinder. Pull the plug and see the color.

You may require to screw the air screw out (1/4 of a turn at a time) and then see if this makes any difference.

[rapidray]

Also, the 83 1100 does NOT have orings in the intake manifolds. You still need to check them for cracks & leaks. I will bet it is something in one of the pilot jets or the mixture screws being set wrong. Ray.