Topic: CB550k - Wandering idle

[MrBaklava]

Hello folks,

The idle on my cb550 seems to be wandering. It’s not surging, but tends to creep up, idling higher and higher as I ride, it starts from 1250 and creeps up to around 3000. When I release the clutch it will then drop back down to 1250, and stay there for a bit, before starting the process over again.

It's almost as if the carbs or the choke is staying open - the throttle releases quickly back to the original position, after being lubed recently. Before that it was a little stiff to return.

Any advice would be greatly appreciated.

[RAFster122s]

Likely an air leak at the carbs to carb intake. They grow a little when hot and when old tend to develop leaks. New Honda OEM are the way to go, many aftermarket do not hold up. Check South Sound Honda of Olympia, WA… low prices and low shipping cost…pick up several parts you need now or in future for distributing shipping cost over many parts…

[C317414]

Check that the ignition advance mechanism is not sticking.  It may need to be cleaned and lubed.

[RAFster122s]

It is not sticking high and dropping but creeping up with time after you have brought it down points to air leak.
Never hurts to lube your advancer yearly, but it will require you to reset your points plate after removing it to get to the advancer...keep that in mind. 
A throttle that takes a long time to come down to idle level can point to lube issue on advancer or cable issue on throttle cables...

[bryanj]

What year and model bike

[HondaMan]

This can also happen when the spark advancer springs are loose. They get heat-annealed from use. I have to cut about 1/2 turn off each coil and re-shape both ends of the springs on these advancers, as they have sacked out from heat-treating by the engine. Some have to lose 1 full coil on at least 1 of the springs. The 750 suffers this even more than the 500/550.

[TwoTired]

Have you done the routine 3k tune up process including carb vacuum balance?

[newday777]

This can also happen when the spark advancer springs are loose. They get heat-annealed from use. I have to cut about 1/2 turn off each coil and re-shape both ends of the springs on these advancers, as they have sacked out from heat-treating by the engine. Some have to lose 1 full coil on at least 1 of the springs. The 750 suffers this even more than the 500/550.

Is there a spring test to measure?

[Deltarider]

The advancer doesn't need lube. If you must - I repeat must - half a drop of light oil is sufficient. I mean the cam's inside ofcourse. The cam's outside does need to be lubed.

[C317414]

The advancer doesn't need lube. If you must - I repeat must - half a drop of light oil is sufficient.

I would not be that absolute.  Any metal sliding surface whose function does not depend on friction can benefit from lubrication.  This will allow it to work better and wear less.  I have always lubricated advance mechanisms on motorcycles and cars.  I normally use a small amount of light oil intended for firearms.

[HondaMan]

The advancer doesn't need lube. If you must - I repeat must - half a drop of light oil is sufficient.

I would not be that absolute.  Any metal sliding surface whose function does not depend on friction can benefit from lubrication.  This will allow it to work better and wear less.  I have always lubricated advance mechanisms on motorcycles and cars.  I normally use a small amount of light oil intended for firearms.

I use a thin smear of grease on the center post for the spark cam. Contrary to popular internet lore, it does NOT '...melt out and end up on the points, fouling them...", or at least, it hasn't since 1968 when I started doing it.