Still popping...

[TitanNeil]

My GS1100GK is driving me nuts. I just rebuilt the petcock (kit) but there was no gas going down the vacuum pipe (as I had suspected and others pointed out) to cyl. #2 anyways. When starting from cold it pops out the exhaust on the left side, and sometimes the 2nd pipe doesn't heat up like the rest, but the 3rd is hotter than the other three. I just changed all the plugs and boots. Carbs, filter cleaned, o-rings replaced. I have good spark but it almost seems intermittent on cyl #2 as it pops a fair bit - I even adjusted the air screws to no effect.

At least while I was doing the petcock and boots today I recovered the seat with a B#H cover I had ordered. At least now it looks super, if not running super.

More hints?

[Steve]

More hints?

I saw no mention of valve adjustment or carb sync.

Also, you don't have "air screws", they are "idle mixture adjustment" screws. They control a pre-set mixture for idle and low-throttle applications. Start with them all out three full turns from lightly seated. After the bike is fully warmed up (go for a 10-mile ride), turn each one slowly, listening for highest engine rpm. You will likely end up with them about 2 to 2 1/2 turns out, but 3 turns is a good starting point.

.

[kruppy761]

I don't know if this is a common problem but I have been working on my GS a 81 750L, and today I was trying to figure out why I was so lean and decided to shim the needles, anyway the part that may relate to you is when I went to pull the #2 needle jet and slide it wouldn't come out, somehow between the time I cleaned the carbs and now which is about 6 months(the were never refilled with gas) that slide had gotten stuck and I found there were some rough spots on the slide area so I smoothed it all out gently with steel wool. I don't know exactly what effect this would have on that cylinder but once I shimmed the needles and fixed that the bike ran much better

[Danjal]

Check your plugs, coil, air filter, pinholes in your exhaust, exhaust gaskets, also. Mine sat for 13-14 years. It started popping after it was up and running right. Specially at 3k RPMs and it just went away after a while. Guess she just needed ran some.

It sounds to me like you need to clean and synch your carbs. Since one pipe is hot and one is cold. Sounds unbalanced.

[TitanNeil]

Thaks Steve for pointing that out - I forgot to mention that I DID do a valve adjustment (bike has 92,000kms so some clearances were tight) 2 weeks ago but not a carb sync. I just got back a few minutes ago from a 2 hour ride around ottawa, just to see if I could locate an oil leak and if the popping would clear up. The leak has stopped, thankfully, but the popping at a constant RPM above 2500 and on deceleration is still present. Idle seems o.k, though.
Once the pop is fixed I am really going to enjoy the bike...

[TitanNeil]

I might add that the fuel milage was really not that good tonight. I started with a 1/2 tank and was on reserve after an hour.
Could I have a sticking slide?

[azr]

You mentioned the pipes are not heating up consistently. That sounds like a carb problem. What did you do when you cleaned the carbs? Looking at your pics you have a custom muffler on her, do you think some jetting needs to be done?

[TitanNeil]

Nope, stock exhaust. I have another pic up of my other GS1100G that does have open pipes - that one doesn't run well, either!

I think I will bring it out to my friends' shop this week and sync the carbs properly. The bulk of the comments about this seem to point to carb adjustments - i'll post an update after the sync. Thanks everyone
!

[Larry D]

Yes, sync the carbs. I forget now which one it was...but, one of my cylinders wasn't firing correctly until the carbs were synced even though I did, what I thought, was a good bench sync.