Jetting or electrical?

[Jonzilla]

Bike is an 82 GS1100G. Starts easily and idles great once warmed up. While sitting in neutral I can blip the throttle with great response and it drops back to 1000rpms just as it should. I can also open the throttle wide open and rev to redline with no studders or flat spots at all.

However, while riding the bike it seems to hit a wall at about half throttle or more. It happens the worst at about 5000 rpms, but seems to be related to throttle position. I can loft the front wheel in 1st gear by applying 1/4 throttle but as soon as I twist a little further is sounds and feels like I've hit a rev limiter.

I have a stock airbox and filter but only have a 4 into one vance and hines exhaust (I purchased the bike this way). I don't know if jets are stock but am thinking this sounds like lean main jetting. I've never played the jetting game but am thinking I'm about to have to learn... Any suggestions for these symptoms? Would lean jetting show these symptoms only under load (while accelerating/riding) and not at all in neutral?

[Guest]

Have you dipped/cleaned/rebuilt the carbs?

[Darin Jordan]

Bike is an 82 GS1100G. Starts easily and idles great once warmed up. While sitting in neutral I can blip the throttle with great response and it drops back to 1000rpms just as it should. I can also open the throttle wide open and rev to redline with no studders or flat spots at all.

However, while riding the bike it seems to hit a wall at about half throttle or more. It happens the worst at about 5000 rpms, but seems to be related to throttle position. I can loft the front wheel in 1st gear by applying 1/4 throttle but as soon as I twist a little further is sounds and feels like I've hit a rev limiter.

I have a stock airbox and filter but only have a 4 into one vance and hines exhaust (I purchased the bike this way). I don't know if jets are stock but am thinking this sounds like lean main jetting. I've never played the jetting game but am thinking I'm about to have to learn... Any suggestions for these symptoms? Would lean jetting show these symptoms only under load (while accelerating/riding) and not at all in neutral?

Honestly, based on my past struggles with my 850 to get it to run right with a 4-1 and K&N Pods, it sounds like it's too rich...

As most of the guys will tell you here... you'll need to go do some plug-chops to know for sure.

You'll also need to know WHAT jets you currently have...

[Jonzilla]

Have you dipped/cleaned/rebuilt the carbs?

no. And on the subject of cleaning the carbs, I have rust in my tank and need to clean/kreem it while I'm at it. Can you point me in the direction of a reliable carb rebuilt kit? I have seen them all over and realize there's some cheap imitation stuff floating around...

[Jonzilla]

Honestly, based on my past struggles with my 850 to get it to run right with a 4-1 and K&N Pods, it sounds like it's too rich...

As most of the guys will tell you here... you'll need to go do some plug-chops to know for sure.

You'll also need to know WHAT jets you currently have...

I have a set of k&n pods. I may try them out and see if it makes any difference. I realize there is no substitute for proper jetting, but maybe trying the pods would shed some light on if it had actually been rich with the stock airbox/filter. Maybe... I need to do plug chops too. Can this be done in the garage or do I have to shut the bike off while the symptoms occur (while riding) to get a proper reading?

[cowboyup3371]

You don't need a carb rebuild kit - just get a set of orings from www.cycleorings.com and a gallon can of Berryman's dip from Autozone or OReilly's. Follow the procedures found on Basscliff's site.

[koolaid_kid]

You will also want new intake orings (cycleorings sells them also) and fuel bowl gaskets. There is a rebuild guide on BassCliff's site that is very well written.

[Darin Jordan]

Guys... with all due respect... I know it's always better to start with fresh stuff, but if the guy goes and completely rebuilds the carbs, and comes back to find the exact same issue, then....

If the bike runs great EVERYWHERE... but when you go past 1/2 throttle and hit 5000RPM or so and it feels like someone just kicked in a rev-limiter (gurgles/flutters/stops accelerating, almost like the ignition is cutting out), then it's possible it's way too rich, which could mean a restriction in the airbox, or something more routine like that. I think it would be good to make SURE it's NOT one of these "settings" type issues BEFORE we go tearing everything apart and end up right back to square one.

I'm only suggesting this because, on my bike, even after I did pretty much everything suggested on BassCliff's site, and here, I still had the issue. Carbs DID need going through, but the underlying problem still existed when they were completely fresh. That was very frustrating.

If the guys bike is running GREAT in all respects, but is having issues when asking for power at above 1/2 throttle, starting right around 5,000 RPM, that sounds EXACTLY like what mine was doing, and it turned out to be the fact that I put the Dynojet Stage III in (165 mains), but left the factory air-intake stacks on inside the K&N Pods, causing the overall mixture to be restricted as if it were stock, but jetting as if it were open... re: RICH... I removed the air-intake stacks and it was suddenly almost perfect.

I'd suggest that you remove the float bowl on one of the carbs and find out exactly what jets you currently have and work from there.

If you remove the stock air cleaner, and the problem gets better, that'll also tell you which direction you need to go (this would show it's currently jetted rich).

I DO agree with everyone here... it is BEST to have everything new, clean, and verified before you start chasing your tail too much, but if the bike is running well all over, and you just are having issues in this one area, I'd see about running that problem down first.

See what Mains you have installed and let us know... The PO may have tried to jet it to match the 4-1, and has gotten it wrong. Check the Air Filter as well, and give it a run without the air-filter installed, if the bike will idle/run that way (Mine would NOT at first, Not without the Dynojet kit installed...).

[Jonzilla]

Thanks for the replies. I'll get the oring kits. I may skip the bowl gaskets since I've had the bowls off and on already and they don't leak. I'm trying to do this thing on the super cheap. This is a $400 bike.

One question I keep throwing around in my mind however is: If it was a carb related issue, would this be happening while revving in neutral also? This missing/sputtering/wall is ONLY happening under load. I realize the carb rebuild is a must do on an old bike regardless. But I'm wondering if a lean or rich condition would only cause the sputtering under load and not in the garage too.

[Darin Jordan]

One question I keep throwing around in my mind however is: If it was a carb related issue, would this be happening while revving in neutral also? This missing/sputtering/wall is ONLY happening under load. I realize the carb rebuild is a must do on an old bike regardless. But I'm wondering if a lean or rich condition would only cause the sputtering under load and not in the garage too.

My bike, with fresh carbs and everything else done, would rev just fine in neutral, and ran around town, down the freeway, and everywhere else, pretty nicely... It would even accelerate pretty hard at WOT... RIGHT up to the 5,000 RPM point, then it was like it had a rev-limiter.

NOT saying that a carb rebuild isn't the answer... it's NECESSARY, even if everything looks OK... but it might be nice to eliminate the possibility that there is another problem before you tear it all apart.

[Jonzilla]

I wrote that last post before seeing your last post, Darin. I was thinking the same thing about a test run with the filters. If anything, its easy and free. I had the carbs off to do a bench sinc a month ago and did not check the jet sizes. I need to do that for sure. This bike has so much potential. I just want to feel it pull all the way to redline as it should... Only 16,000 miles on this thing.

P.S.: anybody got a headlight laying around to sell me? I recently did the "windjammer delete mod" (aka get more chicks mod).

[MisterCinders]

If your problem arises at about 1/2 throttle, it sounds like it is the needle position/size. I don't know if your carb needle adjusts like the needle on my VM carbs, but the slide needle is responsible for mid-range throttle. So you should do a plug chop at that throttle position (cut motor, coast to a stop, pull plugs, curse at burned fingers, pick up hot plug with rag and check for rich/lean). Then move the needle clip or change the needle size (whichever is right for your carbs) accordingly.

[Guest]

First thing I would do is rebuild the carbs. If you do it right you'll know its not the problem. You have CV's on your bike. They're easy to clean.
No build kits needed. www.cycleorings.com and order ALL the o-rings including the intake o-rings. But be forewarned, the intake screws can be a bugger. Don't bust em off.
If you don't have an impact screwdriver, get one. Can be had at most tool and hardware stores for about 15 bucks.

Post up when you get ready to do the carbs and you'll get tons of advise and guidance from folk how have collectively done thousands of carbs.

[Pendulum]

To answer your question about why it only does it when you're riding, it's because the load on the engine is near zero in neutral. In gear, it's got to spin the transmission, chain, rear wheel, etc. Put your 160+ lb self on it and the load goes way up.

[Jonzilla]

Update

So this morning I took it for a test drive with no filters. BINGO! she was running a little weird right off the line (expected) but about 2000rpm up she just kept pulling and pulling!! Would this mean I'm probably rich on the main jets?