Hi guys, I own a GS500 from 1993. Everytime the engine reaches 8500 rpm it falls dead. Cleaned already the carburettors, changed the needles, air filter, fuel filter, .... Even changed the electronic module. Nothing seems to help. Has anybody had the same problem or an idea to solve the problem? Thanks.

I would be checking the main jets.

What do the spark plugs look like?
Not sure what area you are riding in. Here in chicagoland I always change jets based on the season. You need bigger jets in the cold weather or you will be running lean. Try restricting the air intake with some tape and see if it gets better or worse.

I'd also check main jets, what size do you have in there? I'd suggest too big. Bikes run well when slightly lean, until they blow up.
plugs are good?

Check brain, always worth checking brain first...
frequently wrong...

mine did exactly this with too large main jet.

So did i, also wot accleration were coughing and struggling to gain speed. Changing mainjet to smaller size fixed it.

Old GS:s are the best   I live in northern europe so quite cold out here. My GS works perfectly (at least if you ask me  ) and I changed this setup last summer: ORIGNAL air filter (vacuum carbs so original is the best), main 127.5, idle 40, needle one groove up from middle (assuming you have same adjustable needle) and mixture screws 3 full rounds open to compensate new bigger idle jet.

works great, mine did not work at first due to hi-flo airfilter. With original, everything works great 

where di you get original Air filter? I struggle to get them in EU?.

Thanks

Quote from: nurms on January 07, 2021, 03:52:46 AM
Old GS:s are the best   I live in northern europe so quite cold out here. My GS works perfectly (at least if you ask me  ) and I changed this setup last summer: ORIGNAL air filter (vacuum carbs so original is the best), main 127.5, idle 40, needle one groove up from middle (assuming you have same adjustable needle) and mixture screws 3 full rounds open to compensate new bigger idle jet.

works great, mine did not work at first due to hi-flo airfilter. With original, everything works great 

This may be cold weather only kind of thing.

In the summer, my GS with 127.5/40 and a UNI air filter was too rich. I think I'm back to 125 jet. Maybe 122.5 (stock). I can't remember. But 127.5 was way too much in the TX summer. It was like 95F+ every day.

Where exactly are you?

Going from your description it sounds like your bike could be restricted.