engine revs don't drop down

Hi all! Some of you may remember me from a year or two ago. Things got heavy in life and I wasn't able to focus on getting my bike on the road, but I'm back! I got everything back together, and started her up the other night. First time she moved under her own power (in my tenure, at least). First off the engine wasn't running great (haven't really adjusted the carbs yet), and secondly, after revving up to 5k RPMs, the engine would sometimes take 4-5 seconds to fall back down to idle levels after I release the throttle.

I'm pretty sure the throttle cable is not sticking, as it feels pretty smooth when the bike isn't running. Could the carbs be causing this? One more thing is that the engine was only running for 5 minutes, so it may not actually be a problem when it gets real warm, but more of a cold engine issue. However, I'm still curious what causes this. Thanks!!

BTW, I did a few searches and couldn't find anything (didn't really know what to search for), I'm sorry if this is a re-post.

Sure sounds like a sticking throttle cable to me. When you release the throttle, do you notice whether the connection at the carbs bottoms out?

I had that problem on a 750 twin, and it quit after I lowered the float levels a little.

If you got CV carbs the slides could be hanging up. Need to clean and adjust carbs and double check/lube throttle cables.

Look for airleaks around the carb boots and the airbox.

A sticky spark advancer unit may also be your problem. (the weights not returning into place with the throttle closed) It's located behind the points. These should be relubed yearly with dielectric grease. Give it a try, set the ignition timing and let me know. Good luck!

Just to second two earlier posters:
If the throttlecables are not the culprit, it'll be the intakeboots. Had the same trouble a while back.
Jeroen

Thanks for the help! I'll do the WD40 test tonight, as well as lube the advancer.

If your idle adjustment is too high it will cause your problem. If your engine wont idle down corectly without the idle set too low, then you need to sync the carbs.
You need air for it to rev.

I had pretty much this exact same problem.. it was two things for me.

1) The carbs were badly out of sync. I don't totally understand the science here, but if one carb is puffin harder than the others, it'll force the others to work harder, too. I think this is most likely the culprit.

2) The rubber on my choke plungers was bad and it wasn't sealing, so the mix was constantly overpowered. Also fouled my plugs up.