Weak idle until hot

[DimitriT]

Hi folks, got a 82 GS550L with 60k on her. Daily ride. This season seems to have developed a problem where the idle gets weak when the bike is partially warmed up. Bike starts great when cold and idles on choke and off choke (after about a mile on a mild temp day). It also idles strong when fully warmed up (by that I mean a 20 min ride on the highway or something like that). But when the bike is half warmed up (like a slow 2 or 3 mile ride) the idle is really weak and needs a blip of throttle to keep running. I noticed this more after an oil change (Pennzoil 10w40). Also when the bike idles weak it will do a little better in neutral as opposed to being in gear with the clutch pulled in. Could the clutch be dragging? The oil change also seemed to bring on some gear change roughness but that cleared up after a couple of hundred miles. I posted this in carb section but this could go in the engine section.

Do folks run 5w40 oil?

Carbs feel well balanced and clean (rides smooth and strong off throttle). Ignition system looks fine. Yanking the ignition wires indicates that all cylinders are contributing but #3 seems a little weaker but not bad. I've had this bike for 20+ years and this is literally the only problem I have with it.

[Rob S.]

Could the clutch be dragging?

That seems obvious to me. Am I wrong?

[DimitriT]

What can I do about it? Only thing I know about clutch is the little adjustment wheel on the clutch lever. Also why would it idle ok in gear when cold but not when partially warmed up? Does the clutch tolerance change as it heats up?

[Buffalo Bill]

This seems normal to me, old air cooled bikes need to be fully warmed up before idling well, they're analog. It takes progressively longer as the weather gets colder.
PS: In the manual for the same vintage Honda CB750F the use of a thinner oil in winter is recommended.

PPS: As for clutch drag, test that by pulling the bike up on it's center stand and see if the wheel spins while idling in neutral.

[Cipher]

Hi folks, got a 82 GS550L with 60k on her. Daily ride. This season seems to have developed a problem where the idle gets weak when the bike is partially warmed up. Bike starts great when cold and idles on choke and off choke (after about a mile on a mild temp day). It also idles strong when fully warmed up (by that I mean a 20 min ride on the highway or something like that). But when the bike is half warmed up (like a slow 2 or 3 mile ride) the idle is really weak and needs a blip of throttle to keep running. I noticed this more after an oil change (Pennzoil 10w40). Also when the bike idles weak it will do a little better in neutral as opposed to being in gear with the clutch pulled in. Could the clutch be dragging? The oil change also seemed to bring on some gear change roughness but that cleared up after a couple of hundred miles. I posted this in carb section but this could go in the engine section.

Do folks run 5w40 oil?

Carbs feel well balanced and clean (rides smooth and strong off throttle). Ignition system looks fine. Yanking the ignition wires indicates that all cylinders are contributing but #3 seems a little weaker but not bad. I've had this bike for 20+ years and this is literally the only problem I have with it.

Sucking air till heat expands parts and seals.
unless your clutch has adjusted itself by means of cable stretch.
or the oils viscosity rating across Temps is some odd variable. Check Pennzoil site for specs. Iirc only two Temps are test points so........

clutch us easy to check use the fine manual if adjustment needed..