GS1100G Power flat over 6000rpm, 85mph in 5th

not to hijack a thread here but im having a very similar problem i was hoping someone had a sugestion where to start adjusting at. mine runs great any throtle position from idle to around 4.5k and from about 6k and up. in between those ranges however it stumbles horribly like its running out of gas but only in that range. i do currently have it tuned a bit lean due to my jet kits not coming in yet but why only in that range?

[Big T]

I think you need to focus on how it runs in 1st and 2nd gears, and 5th will then be taken care of.

If you're in 1st, can you open the throttle and will it go to 9,000 RPM? It should shoot right up to 9,000 RPM, forcing you to hold on tight. Think a 300HP 327 Corvette for comparison.

[Nessism]

Idle screws won't make much if any difference at WOT. The problem is elsewhere.

Didn't read every reply, but on fuel starvation as possible cause, make sure no kinks or sharp bends in the fuel line. I was riding one day, noticed no power at higher rpm, and it was a sharp bend in my fuel line preventing max flow.

[rustybronco]

In the Clymer manual, I haven't found suggested idle screw settings, can any of you give me some?

http://www.thegsresources.com/_forum...ad.php?t=73723

Another thing I can't find is, how would I adjust or reset the needle depth?
Thanks.

http://www.thegsresources.com/_forum/showthread.php?p=690498#post690498

Some of yous guys have real smarts.
In the Clymer manual, I haven't found suggested idle screw settings, can any of you give me some? Another thing I can't find is, how would I adjust or reset the needle depth?
Thanks.

i believe between 2 and 2.5 turns and tweak it from there.

[Buffalo Bill]

Carb adjustment questions:

Some of yous guys have real smarts.
In the Clymer manual, I haven't found suggested idle screw settings, can any of you give me some? Another thing I can't find is, how would I adjust or reset the needle depth?
Thanks.

[bwringer]

Agreed -- you don't need to modify anything. You just need to get it running as it was designed to. The only setting that should be changed is to richen the idle mixture slightly.

I bet it's running badly in the low end, too, but you don't know it yet -- once you get it running right, it'll probably scare you silly.


I also agree that letting a "pro" touch your bike is sheer madness and despair. Did this "pro" use the shoddy junk jets and needles from a rebuild kit? You must clean and re-use your original hard parts, or buy new OEM.


Just throwing this out there, but I've also encountered a couple of "pro" carb rebuilds where the float heights were set totally wrong. This setting is crucial and precise -- plus or minus 1/2mm either way makes a difference.


Also, make sure your airbox covers and air filter are sealed perfectly. This is simple, takes about $1.99 for foam weatherstripping and an hour or so of your time, and it is mandatory.

6000rpm your throttle should not be close to wide open. You should be a half or less. I would suspect a vacuum leak not pulling the slides up or the slides not moving freely in the carbs.

Don't forget the gas cap vent. This will cause this problem. try running bike with the cap popped loose or off, just not with a full tank so it doesn't splash.
Then check all the other stuff mentioned. Def. sounds like fuel starvation or sucking alot of extra air somewhere.

torque/power peak at 5000? peak power is at 9000 and peak to is something like 7500 for my bike.

[tkent02]

The carbs were pro cleaned and set. I believe the floats were set correctly.

This would be the first thing I would check.
Pros suck unless it's their own bike.
Don't take enough time to do anything right, just do enough to get paid. Anymore a newly trained pro probably doesn't even know how carburetors work.
And most don't give a hoot about anything old.

[Buffalo Bill]

Rode it 60 miles this morning.

This lack of power is only at WOT. When I accelerate, I shift on the torque/power peak at 5000. If I open the throttle slowly, the power gain is smooth. If I open the throttle quickly, there's a little stumble, like the gas flow can't keep up with the engines need. At 6000RPM the throttle is almost wide open, opened slowly or not, only slow acceleration.
The carbs were pro cleaned and set. I believe the floats were set correctly.

[tkent02]

I'm new to bikes, but my background is sports cars. You boomers remember how the factories dropped horsepower in their cars from the mid 70s thru the mid 80s. The '69 Corvette 350 with 350HP, dropped to only 180HP in '77, and only 200HP for '82. Speedometers read only up to 85mph, likewise the Speedometer on this bike.
My theory is: because the power plateau is at 85MPH, the carbs were leaned out for WOT by the factory.

Suzuki did go as lean as they could from the factory to help pass emissions standards, gas is different now, your engine is different now, lots have changed and that super lean factory setting may not be working any more. Some bikes were leaner than others it seems, some still run well enough with the original settings, some don't. Raising the jet needle and using one size bigger main jets would fix this if it is indeed the problem

Before changing anything are the fuel levels in the float bowls correct?

Is every other engine adjustment adjusted correctly?

Is this problem at wide open throttle only, or smaller throttle openings as well?


Also, a clogged exhaust can cause this same symptom, I bought a bike once with a huge ball of steel wool stuffed into the collector of the 4-1 pipe for some reason, it had no power at all except at low RPM. Maybe you have some partial obstruction, dead animals, pack rat nest, cocoons, could be anything.

And, what do your spark plugs look like?
Run it in the dead RPM zone a little while and do a plug chop.

This situation you describe, losing power at a certain number of rpm's, should not happen to a GS1100G. I have a GS1100GK, 1984, same engine, and the power keeps on coming well past 85 mph.

A good state of tune is absolutely necessary for the performance the 1100G was designed to put out. Valves, carbs, plugs -- these are the ones to check out first.

My GK with 130,000 miles pulls like a dream throughout the rpm range. No hesitation, no flat spot, no missing, nothing unexpected. Just smooth, predictable power delivery.