Hi all,
I've searched every way I can think of, and can't seem to find the answer to this issue.
My GS is running pretty good I think, but I finally had a chance to take it on the road for more than a short spin.
I'm noticing that at full throttle (80%+) the bike bogs down and loses power, even losing speed in some cases. I notice it most at speeds over about 40mph, but it may be happening earlier.
If I let up on the twist a little, to maybe 3/4 throttle, it recovers and accelerates, although not very quickly. This could just be the performance limit of the engine, though.
I feel like this issue has been covered before, I just can't find it. Can anyone help?

Maybe outrunning the fuel flow 

Give it a try without an air filter, if it helps, search for a different one.



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Yeah, reading other threads made me think of trying it without the filter.
I'll give that a shot as soon as the rain stops.

Any other suggestions, in case it's not the filter?

Without air filter?.. clogged filter aside... that's gonna play merry hell with your mixture ratio!

Umm. . Also.... filters... no inline fuel filter on the bike at all?

QuoteWithout air filter?.. clogged filter aside... that's gonna play merry hell with your mixture ratio!

Good point, hadn't thought of that. How can I test for air restrictions other than removing the filter entirely?

QuoteUmm. . Also.... filters... no inline fuel filter on the bike at all?

Hmmm...I do seem to recall there being a very small filter-looking thing on the fuel line. Maybe I need to remove that thing and try without it.

Good ideas Janx, thanks!
I'll give those things a try and check back....IF it ever quits raining here. 

Is this above a certain RPM? in a certain gear?

I vote check your battery if it happens at higher RPM. This happened to me and I found that a failing battery can lead to not enough energy for the coils at higher revs - can bog it down...

If you check with a multimeter across the battery terminals you should see 13.6 ish volts at idle - increase the revs and see if the voltage dips below say 10Volts you may need to check your battery / regulator.

The battery is brand new, less than 1 hr of operation.
It's still possible that it's a charging issue, but I'm leaning heavily towards lack of fuel at high throttle openings.
I'll test it without the air filter, just to see what happens.

It may be a couple days before I can try, though. We went from rain to ice to 3 inches of snow.
I really miss summer. 

Give it a go anyway - mine was a faulty new battery (one of the cells had failed internally) - easy thing to check before you take the tank off to check the carbs at least.

I won't speak of the last three months with only 4 days of rain here then... 

Ok, will do, thanks.

I got the same on mine, when I repaced the stock air filter with a $12 chinese clone.
The new airfilter is more free flow, so chances are you just need to upjet (larger main jet), or get a more restricted air filer.

You realize that's the exact opposite of what everyone else is saying, right? 

..... usually..... :rolleyes:

Hahaha right!

Ok folks, the weather FINALLY cooperated long enough for me to work on the GS a bit more.

Here's what I did:
- Removed all the old automotive style (reinforced) fuel line and replaced it with Tygon 1/4".
- Removed tiny inline sintered fuel filter
- Cleaned stock air filter and replaced

The results:
There's still some bogging at throttle openings above ~60-70%, but the bike didn't die.
This is at all speeds/rpms/gears.
However, I've noticed that in the lower gears (1,2) that if I just hold the throttle open, it will spit and stutter, but eventually claw it's way out of the dead area and resume acceleration up to redline.
In gears 3-6, this doesn't happen, and the bike just bogs and chugs until I let off the throttle a bit, then it cleans up and accelerates normally. I assume this is due to increased wind resistance?

Any of this help you guys troubleshoot?
Not sure what else to check at this point.
The bike runs ok, and is rideable, but that fueling issue worries me. I never know if it's gonna die on me a long way from home. 

I'm also having a similar issue with my 92 GS... wanted opinions before i try to troubleshoot myself.

Loses power at highway speeds but only when on full throttle (>80%), this happens both in 5th and 6th gear. Usually end up losing power completely and have to pull over on the highway, after sitting for only about a minute it will start back up and run with no issue until i put it past 80% throttle again. (This only started happening about a month ago and its very frustrating...)

Well, at least I'm not alone!
I never did get any help with this problem, hopefully you'll have better success.
I was able to somewhat get around it by removing a small sintered cone fuel filter that someone had installed, and by removing and cleaning the gas tank vent as suggested in the FAQs.
That seemed to fix my total power loss problem. However, I still have the issue of losing power at large throttle openings.
I'll be interested to hear if you find a solution.

So I Have a small update:
-worked on the bike for about an hour and half just checking for anything unusual. Nothing too noteworthy but heres a couple things I found/did:

-took off the gas tank, checked air filter, seems fairly clean and free of any blockages, could probably be changed soon but is likely not my issue.
-Discovered that the Carb Vent hose was pinched between the battery. http://i.imgur.com/4xEvDlV.jpg
-Checked my spark plugs, appear to spark properly, cleaned them as well, this is what they looked like before cleaning. http://i.imgur.com/P23qCRW.jpg
-Cleaned the air intake on my fuel tank in case theres not enough air getting back into the tank when at maximum fuel flow.
-All fuel lines seem okay and without blockage.

About to head out for a small ride to see if any of this made a difference. Next step is probably checking out the carbs

Well, i was having the same issue with my 08 gs. Tried everithing in carbs, changed jets, used the stock filter, stock exhaust, k&n drop in filter whit and without restrictor, checked diaphragms. Nothing seemed to help. Then me and my mechanic went to a valve clearance check, and for our surprise, we found that the timing in the bike was wrong, luckly it didn't blowed up the engine. We managed to get the engine in the right timing and the problem went away. The diference in performance was incredible, before fixing the timing issue, the bike was tanking off like a 250cc or less.

Maybe it's not your case, but try to check the timing, if you already checked everything in the carbs.