Shim, rejet, or else?

[Anonymous]

Greetings all:

I am hoping I can find some good advice from you all. I am having a bit of trouble with my GS, which I think is running painfully lean.

Trouble started when the weather got cooler. The bike, which had been running well up to this point, started to pop quite a bit. I think it is backfiring.

First thing I did is remove all the California emissions junk. I figured it was adding drag to the fuel delivery, but after removing the canister and the hoses and connecting the hose that leaves the tank directly to the T-connector that feeds the twin carbs (as it does in the non-CA models),the popping persisted. Since the seat was removed and I had easy access to the airbox, I actually was able to feel the pressure caused by one of the backfires.

So here are a few for the experts:

* Can Sta-Bil be the reason for the popping? The problem did not start until I added Sta-Bil to the gas. Within minutes of adding Sta-Bil the condition appeared. I tried to run the gas tank empty and replace with fresh high-test gas, but the popping remains.

* Will shimming the carb needles solve the problem?

* If not, where can I find jets for these old carbs? What jets need replacing, main or pilots?

* Is there a way to make the mixture richer without rejetting or shimming the needles?

* Will my bike suffer damage by running it with the choke lever on? All popping disappears when I pull the choke lever more than half way, which is why I am convinced that my engine is running very lean. However, this seems to be a very unusual and ghetto way to solve the problem, definitely not the cure I am looking for.

And finally, since it is Christmas and internet allows you to find courage in anonimity, I will actually be fresh enough to ask this: Does anyone live close enough to me (Williamsburg, VA) that you'd be willing to meet (your place or mine) and help me with this project? I am trying to learn to work on my bike myself because there are NO decent bike shops in the Hampton Roads area, but I need someone to show me the ropes a bit.

Thank you in advance for your kind help. Any input is welcome.

... and happy holidays to all!

[AOD]

how far is Williamsburg from Asheville, NC?

It sounds like you're describing a lean condition popping...but you need to answer whether it's all the cylinders running lean, or one in particular. Run the engine and get it to pop...shut it down and pull the spark plugs one a time. White around the ceramic is lean; take pictures if you want our opinions on here.

If they're all lean I'd say you're next move is pulling the carbs, cleaning the bowl vents, fuel inlet, and spraying out the jets to make sure you don't have an issue there. You may also want to clean your petcock assembly on the tank.


Removing the california emissions stuff could lean out the bike some because it breathes better. If that's the case, yes you may have to raise the needle a notch.

Keep us updated,

~Adam

[lhanscom]

If you have, or know somebody who has a manual for your bike (anybody out there?) they will tell you what the stock jetting should be, for california, and for everybody else. You may need to get the jets for the 49 state model, but only if they're different. Another option if the jetting is different is to find a set of carbs on eBay. My bikes have always run a bit crappy with Stabil, so that doesn't surprise me, however it should go away as soon as the Stabil is gone. Did you put new gas in before you pulled off the CA stuff? The stabil may have caused the problem first, then pulling off the CA stuff made it do it even without the stabil. How complex is the CA stuff? Could you put it back on to see if it solves the problem?

[Anonymous]

Thank you very much for your replies!

how far is Williamsburg from Asheville, NC?

Wow! Thanks... but I am not THAT fresh... :mrgreen:

Asheville is not reasonably close, I'd really be embarrased to even ask.

It sounds like you're describing a lean condition popping...but you need to answer whether it's all the cylinders running lean, or one in particular. Run the engine and get it to pop...shut it down and pull the spark plugs one a time. White around the ceramic is lean; take pictures if you want our opinions on here.

If they're all lean I'd say you're next move is pulling the carbs, cleaning the bowl vents, fuel inlet, and spraying out the jets to make sure you don't have an issue there. You may also want to clean your petcock assembly on the tank.

I'll print this and get to it ASAP. Thanks!

If you have, or know somebody who has a manual for your bike (anybody out there?) they will tell you what the stock jetting should be, for california, and for everybody else. You may need to get the jets for the 49 state model, but only if they're different.

I have the manual. I will check this when I get home.

My bikes have always run a bit crappy with Stabil, so that doesn't surprise me, however it should go away as soon as the Stabil is gone. Did you put new gas in before you pulled off the CA stuff?

I did. I first ran half the tank empty, and added high-test gas. It did not help at all. Then I ran that tank nearly empty and replaced with high-test gas again... condition persisted.

Only then I removed the emissions stuff. But I am curious... Isn't the CA emissions equipment a canister that carries gasoline and/or gas vapors? The hose that leaves the gas tank goes into this long loop that takes it to the metal canister, then back to the T-connector that feeds both carbs. Is there something else that is CA-only that restricts air intake?

The stabil may have caused the problem first, then pulling off the CA stuff made it do it even without the stabil. How complex is the CA stuff? Could you put it back on to see if it solves the problem?

I thought so at first. Last night, after posting my query, I remembered at least two previous occasions where the engine had popped/backfired. Both times the engine had been fairly cool (running less than 5 minutes). I am guessing that it had always been on the leaner side, and that the cold weather + Sta-Bil just made the problem really obvious.

[Jeff Tate]

Stock GS's ran lean from the factory as did about everything else due to emissions. If yours isn't stock which I gather it's not, it's probably running lean. Cooler weather raises air density increasing air intake causing a leaner mixture. My 1100 has a stage 3 jet kit which is jetted mainly for warmer temps that I prefer to ride in. During the winter it does pop on decel more than any other time of the year(4-1 headers also make this more pronounced). As long it is only a jetting problem and nothing else then raising the needles alittle will help and also going up one size on the pilot jet won't hurt.