TOPIC:

I just recently had the carbs off my car for a routine cleaning.

now when its running and I rev it up to around 3-4k, it seems to take a long time for the engine to come back down to idle.

engine idles ok, knocks, but still idles fine, so I'm not thinking its the throttle cable.


also, while shifting, the rpms dont go down, and sounds like I'm still holding the throttle, but I'm not.


any clue as to what I messed up when I put the carbs back on?

jiggle the handle?...err..choke lever...next time it revs high at a stop. If that doesn't affect it, Inspect the throttle cables for binds/rough spots. The throttle should SNAP shut when you twist it back and let go, with the bike not running.

I'm assuming you meant "bike" not "car"...

Post edited by: Werewolfx, at: 2006/06/18 04:52

yeah, I meant bike..oops.

after looking thru the service manual, I'm thinking it could be the pistons in the carbs not moving like they should.

cause it started doing it when I rev on it at a stop or something, it will take maybe 3-4 seconds to drop down to idle again.

but it could be that I just put the throttle back on again wrong....first time messing with a bike and carburators too.


oh well, I'll figure it out sometime when I'm just fiddling with it, not even trying to fix it.

1983LTD750 said

oh well, I'll figure it out sometime when I'm just fiddling with it, not even trying to fix it.

You should definitely find the problem and fix-er-up right imho...you really don't want your throttle to stick open manuevering among heavy traffic in town (or anywhere for that matter). Having your cable snap is no fun either.

Sometimes your rubber grip on the handlebar can be pushed up too tight on the throttle barrel assembly or be rubbing the break lever assembly and binding. You could need a cable lube or have a rusted pivot shaft on the carbs or even a weak throttle return spring. I'm betting the problem is with the cables or at the carbs.

Just my .02 cents, but we don't want anyone getting hurt around here!

I just had the same problem with KZ750E. Took off all four carb tops while still on bike. Found one slide would not return to bottom with only gravitational pull. Removed all slides. Cleaned needles, slides, cylinders. Oiled slides, cylinders. Checked for submission to gravity several times. Re-assembled.
Works beautimously. Bugs on teeth again.

1981 KZ750E 13,000 miles

83LTD750... I know you have your bike year/model in your handle but edit your profile to add your bike year/model and your location... look at Steve Eliots posting at the top of the section for tips how to do this.

OK... first thing is, do you have Keihin or Mikuni carburetors? Both use one throttle cable to open the throttle I believe. You should see visible slack in the cable where the exposed part enters or connects with the throttle on the carb assembly. If your cable is tight, it will behave as described. Loosen the barrel adjust at the right switchgear and turn it toward you to gain some slack. LOOK AT THE CABLE as you do it to ensure the correct amount of slack. You should see slack in the cable.

Did you take the carburetors apart for the cleaning. The butterlies on a Keihin set can get sticky if you didn't reassemble properly. The last thing, did you remove the mixture screws when you had them apart for cleaning?

Air leaks can cause this symptom, I had similar problems.

Check first to make sure it's not a mechanical problem: make sure that your throttle grip's not rubbing, your cable's not sticking, and your butterflies are closing when you let off the throttle. To do this, twist the throttle with the ignition off, listen for the butterflies closing in your carbs.

Once you've eliminated all these possible causes, start the bike and check for air leaks. There are a couple ways to do this, one being to squirt WD-40 on different parts of the carb assembly while the bike is idling. If the idle drags down, then you've found the leak. Another, cleaner method is to use an unlit butane torch. Open the valve on the torch and hold the end to suspect areas on the carb assembly. If your idle goes up, you've found your air leak. Possible trouble areas to look for are the tubes connecting the carbs together, around vacuum nipples, around the lids holding the diaphragms in.

Let us know what you find...