Creeping Idle & terrible throttle response

OK, so I've been trying to work through this problem for a while now. I re-built my carbs from top to bottom. My symptoms are a creeping idle. While the bike is warming up, I get fairly good throttle response. When I rev the bike to 4000 rpm's she'll slowly return back to a 1050 rpm. However when the bike is warmed up, she wants to stay at a high 3000-4000 rpm's. I've shot flamable brake cleaning fluid around the carbs looking for an air leak with no luck. I've adjusted the idle screw & balanced the carbs. I've made sure that all my carbs did the clunk test and, they passed with flying colors. I still can't get the proper throttle response & I can't get the carbs to stop creeping back up to a very high idle. I must be missing something. Any help is always appreciated!

Thanks
Ken

 

could be a cracked diaphragm. the idea- as I learned from reading a post by Rick- is that once you crack the throttle, the diaphrams pull up with vacuum to expose the main jets/emulsion tubes. if they dont come up quick, you would have very little throttle response. also, the vacuum leak would cause the idle to return slowly as the engine is pulling the air and fuel in from the pilots.

just my .02

 

Hey thanks helmet, I had thought that I looked the diaphrams over but, I'll take another look. I do have some extras in the garage if I find a bad one. Makes sense that could effect the throttle response. I'll post anything that i find so that, it might help someone else out that is trying to work through the same problem.

Ken

 

I had the same problem. Idle would start out normally and then the hotter it got the higher the rpm's would go. Mine would max out between 2 and 3k after 30 minutes or so of riding. Really humiliating sitting at a busy intersection with the bike running away with itself. Someone here on the forum told me how to handle it. Sorry but I don't remember who to give credit to. I adjusted the rpm once the bike was at full temperature and full runaway idle. I set it at 1050 and it's never done it again. I will warn anyone though, either use pliers or wear gloves so as not to burn yourself.

Also, along the lines of what Helmet said, lube the diaphrams. My BIL worked my carbs and he used plain old Vaseline on the diaphrams. It worked (and still is) great.

 

Thanks Wyldman for the suggestion, I'll give that a try. Do you now have to choke your bike to get her to start now or, are you getting a rougher idle for the first 20-30 minutes? I just checked all of my diaphrams and, they all seemed good. I held them to the light and looked for pin holes while giving them a little stretch then, streched the edges near the piston to make sure that they were all connected. I'm running a K&N air filter in the air box and, I got some #109 main jets, as per chacal's chart for the K&N air filters. Could it be that I need a smaller size jet, due to the fact that the new air filter is pulling air more easily? Is there anyone else running a K&N air filter that had the same kind of problems? Another symptom that I have is, that when it starts to idle up higher, I'm able to bring the idle back down a bit by riding the clutch a bit with the brake on. This brings the idle down just for a bit but, as the engine warms up more, clutch riding becomes more useless as a control for the idle.

I'll keep looking
Ken

 

I would start by getting it warmed up and cranking the idle screw back. get it to a workable idle so you can actually tune the rest to the filter, etc.
I have a K&N filter, but according to them, no rejetting was required. i am going to some plug chops tomorrow and will report the results. then I get to finish painting

 

Ken my choke has never been a problem. Works just about like any other bike I've owned and is SMOOTH from the get go.

 

Hmmmm? Well I'm going to look for a UNI filter local and, if I can't find one then I'll be hitting up chacal for a replacement. That was what I had in the bike before the re-build and, seemed to have worked fine. I still have all of my old jets so at least I know what was working in the bike before I started having troubles. We'll see how that works and, I'll report back. Thanks for all of the input guys!

Cheers
Ken