Losing Power in higher gears at 5000-6000 RPM

[mr72]

Haha, I hear you. I've been following your progress with much empathy.

I only wish my problem was as simple as yours

Yeah, it basically is the opposite of what it was doing before.

I think that means: you fixed it!

And now you might have a new problem that is probably much easier to fix.

[rscottlow]

I think that means: you fixed it!

And now you might have a new problem that is probably much easier to fix.

I sure hope so lol. This one was a pretty easy fix...I just didn't know what to look for, so it took a long time for me to find the problem. I didn't get a chance to tinker anymore over the weekend, but I was out at my great uncle's house setting up tree stands yesterday--he's retired, and is always looking for something to tinker with--and he mentioned that if I can't get it running right before I put it away for the winter, to bring the carbs out to him and he'll play with them. Worst case scenario, of course, but at least it's another option to fall back on. That being said, I really hope I can get it running properly before I have to put it away for the winter.

[chornbe]

Other things I noticed...once I get it up past where power initially drops off (usually by letting off the throttle some), I can keep accelerating...but only to a certain point. For example, I couldn't get it above 10,000 RPM in first, 8,000 in second.


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FWIW, I just took mine to NC and TN after doing a full cleaning on the carbs (the bike sat in weather for ~3 years before I got it - the carbs were a mess inside). I have basically the exact same issues that are mild at sea level (I live in Delaware, our biggest hill is about 300 feet LOL) and severely exacerbated, to the point of "oh shaZam! I'm gonna die" at ~5,000 feet elevation.

I can't find anything else wrong anywhere. (I work IT these days, but my first career was in auto- and motorcycle-mechanics)

Bottom line: Jet kit ordered, and in your case I'd do the same (with a full needle kit and perhaps slide drill).

[chornbe]

Note: my previous response was before seeing you found an issue with the diaphragm.

When in doubt, back to basics. These bikes are basically 80s and 90s tech parts bin bikes, which means they come out of the factory running lean as all heck, rather than using modern fuel systems, to make the EPA happy.

Replace the diaphragm - it doesn't take much to damage them to the point of not working correctly, then get a decent stage-1 kit with needles, and follow the directions for stock airflow (filter and muffler - assuming they're stock).

If you suspect the carbs' cleanliness before doing the kit, FULLY disassemble them (don't be too intimidated and take pictures along the way), then soak the bodies in a can of this stuff for a few hours, rinse with water and blow them out with compressed air, making sure to shove lots of air in every single hole, orifice, etc. (wear safety glasses)

If that doesn't do it, you have another issue, and yes, it's *always* a good idea to thoroughly check the rest of the fuel system - ensure flow, that the petcock isn't hung up, the fuel pickup tube is clean-n-clear, etc.

Parts cleaner mentioned above (generally available at most auto parts stores, too):
https://www.amazon.com/Berryman-0996-Chem-Dip-Carburetor-Cleaner/dp/B00DSMEL2A

[rscottlow]

Finally ordered the replacement diaphragm this morning. I'm crossing my fingers until it arrives, in hopes that all of my problems will disappear upon installation...

[rscottlow]

So...you want to talk about checking the simple things first? To make a long story short, I think I've fixed it...

Somewhere along this painful journey of not being able to ride my GS, I pulled the right spark plug to try to determine whether it was running rich or lean. When I did, I was being lazy, and only took a couple of the right side fairing screws out and kind of held the fairing out of the way instead of taking it all the way off. When I put the plug back in, I must not have reconnected the spark plug wire. 

When I re-seated the diaphragm, the carbs issue was resolved, but it was still running all around sluggishly. I ordered the new diaphragm in case the old one still wasn't sealing correctly, and I installed it this morning. I took it out for a test ride, and it was hardly improved. I decided to check the plugs again, so this time I removed the right side fairing. Lo and behold, I've been running on one cylinder. So I feel like a total dummy, but I reconnected the spark plug, started it up (to a much healthier sound...I don't know how I didn't notice it before), and let it run for 20 minutes or so to clear out that right cylinder. I reset the idle, and it seems to be running fine. I'm working from home today, and I get off in 15 minutes so I'll take it out for a ride to see how it's running under load. I don't want to jinx it, but I think my problem has been solved 

[rscottlow]

Hahaha I'm a dummy. But it's fixed, and that makes me happy lol.


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[qcbaker]

Great to hear you fixed your problem! Ride safe mate.

[Big Rich]

I would've never said "connect the spark plug boots"..... haha.

Glad to hear you're all fixed up!