So my GS has been having some highway troubles. If I'm cruising along a flat highway, I can't get past 75mph. If I'm at 70-75mph in 6th gear at 6,000 RPM, with the throttle all the way twisted back, it refuses to go over 6,000. I usually have to ride in 4th-5th gear just to get it up to 70. Downhill it can obviously go faster, and uphill is a real drag. I have to downshift into 5th just to keep the bike above 65. And don't even get me started if there is a headwind WHILE going up a hill. I'm not a huge guy either (175 lbs.).  Anyone having the same problem or have ideas??

I recently took my carbs in for a cleaning, and they only took off the top pieces. They didn't even bother opening the float bowls to clean them. It only cost me $45, but I feel like they didn't care so I'm done taking my stuff into Suzuki.

Are you sure it is running on bother cylinders?  What kind of fuel mileage are you getting?

-Jessie

I would check the cylinders as well, if that's not it try running the bike on prime.

Quote from: BaltimoreGS on July 16, 2010, 03:32:11 AM
Are you sure it is running on bother cylinders?  What kind of fuel mileage are you getting?

-Jessie

Both exhaust pipes feel hot to the touch. I'm not sure of any other way to check if it's running on both cylinders or not. I am getting a terrible 35-40mpg.

pull the plugs and see if theyre the same color on both sides. if there's a different color between the plugs, switch them and see if the color follows the plug or stays to the cylinder. could be a bad coil if one cylinder isnt firing

What kind of bike shop only takes the tops off the carbs to be cleaned,the crap ends up in the jets in bottom what jackass`s!If its not the jets carbs need a tune,unless you have a ropey chain,sticky brakes.
Combo Jay.

The brakes aren't sticking, already checked that. Could it be that I need a carb synch? I have never had that done and have put over 8,000 miles on it.

if you have stock exhaust, they have that crosspipe that allows for exhaust to equalize between the two pipes, which also allows both pipes to heat up even if only one cylinder is firing. unless you can confirm that both pipes are heating to the same temperature, it's still a possibility youre running on one cylinder.
things i would look over would be:
1. how the exhaust looks and smells
2. color of the plugs (post up pictures if you dont know what plug colors mean and someone can hop in to help and tell you)
3. condition of the petcock.

good luck figuring out the issue

I would go to harbor freight (sears probably has them too) and pick up the cheapest infrared thermometer you can. I got mine from HF for under 5 bucks. That will tell you if both exhausts are heating the same. Check the plugs, if they're similar in color, post up what color they are (options are white, brown, or black (wet or dry). Does it make any popping noises or sputtering when you try to accelerate?

Taking the tops off the carbs won't do anything, and if they lost the tiny little o-ring could have made it worse. I think its a carb problem, either dirty, out of sync, or needs a different jet. You need to take the carbs off and really clean them. Then make sure you don't have a vaccuum leak somewhere because they forgot to put a cap or tube back on.

If it is only running on one cylinder all the time (not just under load) you can pull off the spark plug wires one at a time.  If it keeps running with the wire removed then the opposite cylinder is working, if it dies when you pull the wire off then the cylinder with the wire still attached is not working.

-Jessie

When were the valves last adjusted?
I bought my 98 with badly maintained valves, and as soon as I fixed that it felt totally different, powerwise.

I had weak engine, hard starting and poor mileage until that was sorted out.

I don't think it will go anywhere near 75 on one cylinder. Also it would shake.

Nobody else thinks he has fuel starvation issue? I say check out petcock and lines and float valves.

Quote from: johnny ro on July 19, 2010, 04:19:20 AM
I don't think it will go anywhere near 75 on one cylinder. Also it would shake.

Nobody else thinks he has fuel starvation issue? I say check out petcock and lines and float valves.

I am confident that the floats are the problem now. The engine is running too rich which has semi-fouled the plugs. The floats bowls need to be cleaned really good and readjusted. Hopefully that will sort the problem out.

I had exactly the same problem, in my case it turned to be the right carb diafragm spring that broke inside the carb and froze the intake all the time closed, that way that cylinder couldn't get mixture enough to run properly.

As you said you've been servicing the top of the carbs, well might be it. A spring out of position could do the same.