cold engine fine, hot engine idling fast

i'm stumped.
everything is tight and runs tops as far as i can tell. but recently i've noticed some odd behaviour from the engine/carbs.
when the bike is cold, say for the first 10 minutes or so, the idle is bang on.
but once warm/hot the idle runs as high as 3k. yeah, no joking.
i remember at the end of the season last year the foam pad inside the airbox was removed, or what was left of it, otherwise no mechanical changes at all.
bike is a 75 cb550f with only 8000 miles on it. everything engine-wise is total stock.
any ideas/tips/tricks for me to correct this bother?

much thanks,
andrew
ottawa, ontario

bluayeddvl said:

i'm stumped.
everything is tight and runs tops as far as i can tell. but recently i've noticed some odd behaviour from the engine/carbs.
when the bike is cold, say for the first 10 minutes or so, the idle is bang on.
but once warm/hot the idle runs as high as 3k. yeah, no joking.
i remember at the end of the season last year the foam pad inside the airbox was removed, or what was left of it, otherwise no mechanical changes at all.
bike is a 75 cb550f with only 8000 miles on it. everything engine-wise is total stock.
any ideas/tips/tricks for me to correct this bother?

Click to expand...

Had the exact same problm with my seca.

In my case, the spark plug boots needed to be replaced (had old metal ones on there - which apparently suck bad). I also had the carbs cleaned / synced at the same time, so either sould have been the source of the idling problem - more likely a combination of the two... And my motor (aside from a 4-into-1 pipe and a UNI filter in the stock airbox) was also stock.

My idle always goes up as the motor gets warm.
Kinda the nature of the beast in my opinion...

Same issue. I just turn the main Idle screw counter clockwise and vola.. no problemo..