Crazy Idle rpm's! What gives?

[Anonymous]

The engine idle drives me crazy on my 1980 GS1100ET. Sometimes it idles very high, between 1500 & 2000 rpms. Then all of a sudden it will idle down correctly, around 1000 rpms. "Sometimes" I can get it to idle down by revving it up very high, but not often. Often it idles in a mid-range of 1400-1500 rpms. Anyone know what is up with this? Other than this the bike seems to be running great! It has just started feeling like a little missing is going on when taking off a little hard, around the 5000 rpm range, but smooths out quickly. That has just started and I figure its simply time to adjust and tinker during the upcoming winter and is not related.

Any and all help is appreciated guys so thanks in advance.

Steve

[gsBert]

are your slides maybe staying stuck open?

when you have the airfilters/airbox off, make sure the slides dont scratch or bind, they should move freely with jsut the spring resistance to be felt.

[Tarbash 27]

CHECK THE THROTTLE CABLE'S AND MAKE SURE THEIR NOT KINKED OR STICKING. HAPPENED TO ME TODAY. TOOKE ME ABOUT 5 MINUTES TO FIGURE OUT WHAT IT WAS.

[gsBert]

yeah, what tarbash screamed could be it also...

hey tarbash: WE ARE NOT DEAF! typing in caps is considered screaming and rude, do a google search for "netiquette" please...

at least it makes it really easy to find which posts are from you... my trade mark used to be i would not use the space bar, soallmyemailswouldbeonelongword...

did you finally get your jets?

oh, heyblue: what kind of carbs do you have? one of my bikes has mechanical slides and i have 2 throttle cables on them, one to open and one to close, if the close cable is loose, that could also possibly cause it...

[Billy Ricks]

Cable could be a little tight or gummed up as well. You should have a little play in the cable before it tightens up and and acts on the carbs.

[gsBert]

i just notices tarbash's sig: he removed the push cable. if its gummed up or seized, (or removed, or simply cut) your carb slides would only lower by spring/gravity... any little resistance in either system(spring, cable or gravity) could keep them up...

of course this only applies to a 2 cable push-pull throttle setup.

if you have regulat cv carbs, make sure that the slides ar lowering (same thing basically) here you'd look for a worn rail that the slide slides in, or a binding throttle cable, (but that would keep all 4 slides up)...


remove the airbox and push your slides up and down by hand (if you have cv carbs, if push-pull, activate the throttle a few times, empty your float bowls first if you have an accelerator pump), is any of them harder to move? if yes, you found your problem, tear them apart and replace the slide rails and/or the slides. might as well do all 4 because if one just went, the others might soon as well...

mind you this is just speculation, your problem might be elsewhere too, but its an easy thing to try...

my 750 did that before, and it eventually stopped doing it. i remember changing the throttle cable; the old one snapped and i had to use the choke to be able to continue riding the expressway till i got home. but i can't remember if i changed it before or after the problem went away...

oh, one more question: does it only do it after the bike is warmed up really good? like only after 15- 20 minutes of hard riding?

[Dark Jedi]

OOH OOH!

A helpful tip: Dry lube, like graphite, is great in cables. Pull the caps loose at each end and wash them out with a mild solvent, then blow air through them to dry thouroughly.

Then blow graphiter in to them. Make a huge mess, graphite everywhere. Cap them back off and marvel at how easy they move.

[Desolation Angel]

GEE, LOOKS LIKE IT COULD BE ANYTHING, HUH?

[KEITH KRAUSE]

Try adjusting the throttle cable for about 1/8" slack as you twist the grip. There should be a little play in the grip before the throttle actually starts opening the carbs.
If still doing it, spray some electrical lube on the ignition mechanical advancer. Make sure it operates smoothly.
If still doing it, your description could be an intake leak. Try tightening all the manifold clamps first and test. Try to set the idle to the correct speed, about 1,000/1,100 rpm's. If the rpm's are also slow to return to correct idle, this also suggests a lean condition/intake leak. If the bike idles significantly higher after warming up, this also suggests an intake leak. Most likely the manifold o-rings but possibly the manifolds too. Takes only one carb to effect the rpms this way.