Misfiring 1100..?

[terbang]

I just recently re-ringed my 1100 E and for the first 500 K's it was fine though I rode it fairly quietly. However now it has developed a misfiring band. When it's cold it seems to be fine but when warmed up, when I open the throttle fairly wide It starts missing and surging at around 4-5000 RPM then it clears and its off (nearly tearing my arms off). When gently revving the engine static it backfires on rundown but seems to rev freely and smoothly.
I suspect things are a wee bit lean and will have to tear my carbs down and have a look.
What do you guru's out there in GS world think..? Any advice..?

[49er]

Did you do any work on the carbs during your re-ring job?
It sounds as if your needle positions are too lean. The fact that your engine pulls well higher in the rev range means that your main jet is not causing any part of the problem. When the engine pops on rundown, this indicates a lean condition in that part of the rev range, caused by either an incorrect needle position/slightly lean pilot circuit or a leaking header pipe/pipes. If you're still running an airbox, check that all the rubber boots and covers are sealing properly.

[terbang]

When I had the engine apart I whipped off the float bowls just to check the condition and for any crud. They were fairly clean. I am using a stock airbox and will check that out along with the needle positions.. The plugs are a fairly light colour so It really seems to be a lean issue.
Thanks BR

[terbang]

Hmm had some fun today. Checked all the airbox boots and covers and they seem to be fine and I had replaced the intake manifolds (the rubber ones) and they seem to be fitting well. I raised the needles up (to rich) one notch. As before she fired up beauty and seemed really responsive however after she warmed up again it ran real rough, way rougher than before. Even at static it is now running real rough. Have I got an ignition problem..?

[49er]

Hmm had some fun today. Checked all the airbox boots and covers and they seem to be fine and I had replaced the intake manifolds (the rubber ones) and they seem to be fitting well. I raised the needles up (to rich) one notch. As before she fired up beauty and seemed really responsive however after she warmed up again it ran real rough, way rougher than before. Even at static it is now running real rough. Have I got an ignition problem..?

Bruce, I might have put you crock from your first post. You said that the bike misses and surges, then clears at around 4-5000rpm and nearly pulls your arms off. I took this symptom to idicate a leanness on the needle setting. The fact that it runs ok when cold but gets worse when hot indicates that you have a rich condition. This seems to be confirmed by the fact that you say it is now worse since you raised the needle position.
Did you shift the circlip closer to the taper or further away from it?
Cheers
Ian

[Suzuki mad]

Doesn't sound like ignitor (CDI) unit as it runs well at high rev but could be the advance unit on the end of the crank with the contacts not working due to springs.

It may well be a blocked jet in the carbs as the main jet works in a different way.

Is the choke coming off fully on the slides? These do have a habit of keeping slightly open if the cable is old or there's rubbish on the slider between each of the carbs.

Suzuki mad

1981 GS1000ET
1983 GS(X)1100ESD
2002 GSF1200K1.

[terbang]

Well I sure had some fun, tearing out what little hair I've got and went right back to basics. What would you know I changed fuel caps with my 400 and 'ping', problem fixed. Dismantled the 1100's cap and there was all sorts of crud on the tiny wee hole in the body of the cap... Fixed...
Thanks for the input on the thread as it stimulated me to start searching in the right direction.

[chef1366]

Dang, fuel tank ventilation. Good call.