rough idling - GSX 600!

[Cruiser]

hey ppl,

just bought a 1990 gsx 600f, got a problem with it tho, think it could be carbs but not too sure...

when starting it from cold it needs choke for about 10 minutes to keep it from stalling on idle, and when warm enough the idle seems to be lumpy, not staying at a steady rate (between 1600 and 800rpm).
when using the bike as well, its as if theres not enough fuel or air getting into it an struggling to make enough power, however it will sit at a steady speed so still usable. then when slowing down, it will go down too 2000rpm for about 15 seconds, then drop down to the rough idling stage again (1600-800rpm). im thinkin possibly something to do with carbs? sinc buying it ive give it some good long runs (70 miles ish each) hoping it would clear out but after 200 miles with fresh fuel nothing has changed.

any help would be much apreciated!!

thanks

[Finglonga]

Was it from a dealer? If so take it back, garage or private you should have noticed that on the test ride and got it sorted before handing over cash.

If not when was it last serviced? How clean is the air filter when were the carbs last balanced?
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Andy Sez....
F.Y.Y.F.F.

[Pete.]

Sounds like the float levels need raising. Remove the carbs and give them a thorough clean. Turn them upside-down and measure the height of the floats at any point (usually the highest) above the carb bowl mating face. Choose the one that is lowest and drop it half a millimeter then make all the others the same by bending the tab that presses on the float valve. Now re-fit the carbs and check the balance, see if it improves.

Also, change the spark plugs.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Ichy]

check all the vacuum hoses and manifold connectors for leaks.

I've known a few of these to have problems simply down to dirty plugs creating an erratic spark. Change the plugs rather than clean them. If your feeling a bit dangerous pull each plug cap off while the bike is running, I wear rubber gloves! Revs should drop, if they don't you've found the dodgy cylinder.

Next I would check the mixture screw. Screw each one back in, counting the number of turns, until you just feel resistance. Make sure they are all set the same. Standard is around 1 1/2 turns.

Float height should be 14.6mm +-1mm BTW.
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