'80 GS550 running issues

[robmilchling]

Despite many searches I didn't find much that seemed to match the symptoms I'm having. I come from a strong automotive background but this is my first time really dealing with carbs extensively.

A previous owner installed a kerker exhaust and pod filters and supposedly rejetted the carbs but I have no specifics provided to me.

Issues:
- it seems to be lacking in mid-range power and the exhaust is popping some. But, it seems to happen regardless of the amount of throttle input. It performs the exact same way from 1/2 throttle to full throttle. same lagging, same popping, same acceleration. But, this only seems to happen ~5k rpm to 7k rpm. Once out of that zone it seems to want to scream. This may very well not be a carb issue but with the other problems, I really dont have any idea.

-When starting the choke mechanism seems to be malfunctioning. Only on some occasions the idle will stay higher, often the bike just wants to idle low and die with the choke on.

-I constantly have to play with the idle to keep it running as it always changes, and sometimes after a bit of a run when I come to a stop it wants to idle at 3k.


I tried finding a few answers but only seemed to find fragments of what the possible problem may be. I am planning to do a valve adjustment soon and possibly clean and adjust the carbs a bit, but figured I'd ask around a bit before I started screwing with things.

Any help will be greatly appreciated. Thanks.

[tkent02]

If you don't know about the jets, you need to find out. Most everyone who messes with jets on these bikes is really clueless about what jets even do. It sounds like the carbs need a thorough cleaning anyway, new O rings, dipped, the works - not just "clean and adjust the carbs a little bit".

Cliff will be here soon to give you a "to do" list, it includes pretty much everything an old bike needs to have done once every couple decades or so.