Weird Idle Problem

[MickaelKZ]

Well I had that pesky little fuel leak pop back up today. So I pulled off the carbs and had a quick little look at them to see what I could do to fix the problem correctly.

Well I pulled them apart and changed the o-rings on the fuel fitting and added two new ones around the "T" section of the valve to stop the leak. It worked like a charm. Also while I had the carbs off and pulled apart I sprayed them down nicely with carb cleaner. The looked like new when I was done with them, on the inside that is.

So I put them back on and check all the fittings to make sure that everything is snugged up properly. Then I fired it up to check it all out. When I fired it up the idle jumped up way to high. Probably around 10 grand on the tach. I couldnt tell for sure the exact RPM's because I no longer have my tach on the bike. But I know they were way too high.

Now I had to adjust the idle screw kind of high, around 3500 RPMs before the cleaning, to keep it running when idling at a stop. With the idle screw any lower it would die out. Also, I didnt fully take the carbs off, I just pulled them off the motor left them intact and sprayed carb cleaner down through the throats.

So could my problem be something as simple as the idle screw was set too high to compensate for the dirty carbs prior to the cleaning? Or could this be something worse?

They are CV carbs off an 82 KZ 305.

[StarGate]

Make sure you didn't get your throttle cable kinked or in a bind. Key off, open the throttle all the way and let it go. Does it snap back to idle position? Did any vacuum lines or caps get knocked off or left off? Adjust the idle screw back out to make sure it's not too high. Did you get the carbs seated back into the holders good and all the clamps are tight? If it's none of the above then get the carb cleaner out and while it's "idling" (yea I know you can't really call it idling ) and spray the cleaner around the carb holders to see if theres an air leak. Could be a crack in one of them. Just listen for the rpm to change while your spraying.

P.S. I hope you used fuel resistant (aka Nitrile) o-rings.

[MickaelKZ]

My throttle cable is good. It snaps back freely and everything. There were no vacuum lines hooked up to my carbs though. There are some hoses hanging freely from the bottom but thats it. My manual says they are supposed to hang freely. Everything was seated good and tightened down firm. I know my carb boots are cracked a bit, but no worse then they were before I did the work. I checked eveyrthing as best I could for air leaks and all that.

Im gonna try the idle screw first tomorrow and see if thats it. If not then I am going to go back over everything you have listed. I appreciate you saying those cause come tomorrow when I go to start working on it I would have forgotten the most simple things.

And yeah the o-rings were good for use on fuel lines and such. I triple checked that. lol

[StarGate]

If you know for a fact that the carb holders are cracked, you need to stop wasting your time trying to get that engine to run right until you can get some new ones installed. No amount of adjusting on idle or mixture or changing jets is going to make it run right. Because that rubber expands and contracts with temp changes and it's just a never ending fluctuation of the mixture the engine is receiving. And just to be sure we're on the same page here, when I say carb holder, I'm talking about the rubber that connects the carb to the cylinder head not the rubber that connects the airbox to the carbs.

[MickaelKZ]

Well right now I cant get any. I just cant afford to drop another $60 into it this week. And I cant be without it. Right now its my only vehicle. I just dont know what the problem is. I adjusted the idle screw all the way in and its still idling really high like that.

Could it be that its trying to cycle out whatever remaining carb cleaner was left inside the carbs?

[Stormdragon]

Originally Posted by MickaelKZ

Could it be that its trying to cycle out whatever remaining carb cleaner was left inside the carbs?

No.
It's most likely exactly what Stargate said. When you pulled the carbs off, you flexed and stressed that cracked rubber even more than it already was, which happened again when you reinstalled them. You are most likely sucking air directly through small cracks in the carb boots. If you really want to prove it to yourself, start the bike up, and spray carb cleaner directly on the boots, and listen to the idle change as the engine sucks the carb cleaner through those small cracks in the boots. Then go get yourself some new ones.

[MickaelKZ]

Well I pulled the carb boots and inspected them. They were cracked around the base and in a few other spots but I couldnt see any cracks that went all the way through.

When I pulled the carbs off, I noticed that the rear butterflies where partially open. So I adjusted the idle set screw so that they were back closed.

I have put some RV silicone gasket maker over the cracks and worked it into them really well. Im going to try letting it dry then using the gasket maker in the re-installation of the carb boots to see if there are any spots that the bots werent sitting flush against the motor and to try and completely seal it all back off. This isn't going to be a permanent fix, but I'll see if it fixes it before I go and spend the money to buy new carb boots.

Thanks for all the help guys, and I'll keep yall posted as to how things work out.

[MickaelKZ]

Ok, so I figured out the problem. It was an air leak. But not from cracked carb boots. They were cracked but not enough to let air in. What had happened, is when I put the carbs back together the bottom bar holding them together had been installed upside down. So it was causing the carbs to not sit flush in the boots thus having an air leak.

I noticed this today when I pulled everything back off and fixed it. Also the bike had a bit of a problem running with the choke all the way open and maintaining idle while stopped and also idling high normally. Somehow taking the carbs off and just spraying some carb cleaner in them fixed just about all of this. So the bike runs great now.

I'm still missing the grips for it, but I will post some pics of the finished product tomorrow.

[StarGate]

Air leak causes all the problems you have been describing. Fixing the air leak is what took care of the problems. Now do yourself a big favor and start saving up to buy some new boots as soon as you can.

It wouldn't surprise me if you still had some air leaks that just aren't as severe now and they will start to show up randomly.