1981 KZ750 LTD Idling Issue

After much work on the carburetor and new ignition coil, I finally got the bike running really good. The only problem right now, is it won't keep idle.

When I start it, I have to increase the idle adjustment to keep the bike running. Then, once the bike warms up, the idle is too high.

Just wondering if there is anything specific to check?

Also the bike only runs really good with the pilot adjustment screw at 1 turn out from seated or less. Anything above that and it has no power and doesn't run good.

This bike has the Keihin CV34 carburetors. The Clymer manual I have says when you turn the pilot screw in clockwise it is richening mixture and counterclockwise leaning it out.

I checked my spark plugs to see if that would help. And they have no residue on them, I am wondering if I am running it too lean?

Spray some carb cleaner around the boots mounting them to the motor and to the air box side. If there is any change in rpm you've found a leak. You might want to run some injector cleaner in your fuel too. No residue on the plugs is a good thing. Are your headers bluing? They will blue rather quickly if you are running lean.

I have checked for leaks before, but I will try it again.

I have black painted pipes on so the blueing thing won't work.

Thanks.

How long are you using the choke for? Mine idles really low if I take it off choke too soon.

brox wrote:

After much work on the carburetor and new ignition coil, I finally got the bike running really good. The only problem right now, is it won't keep idle.

When I start it, I have to increase the idle adjustment to keep the bike running. Then, once the bike warms up, the idle is too high.

Just wondering if there is anything specific to check?

Also the bike only runs really good with the pilot adjustment screw at 1 turn out from seated or less. Anything above that and it has no power and doesn't run good.

This bike has the Keihin CV34 carburetors. The Clymer manual I have says when you turn the pilot screw in clockwise it is richening mixture and counterclockwise leaning it out.

I checked my spark plugs to see if that would help. And they have no residue on them, I am wondering if I am running it too lean?

Hi Jon

Idle adjustement should be done when engine is completely warm. This usually means rinding a few km/miles to warm up carburettors too. If adjusted before engine is warmed up it will have a high idle when warm.

Pilot screw. I´ve heard a pretty simple rule determining the operation of pilot screw. If it´s located on the intake side of carb body (between carb body and engine) then it probably is fuel/air screw. This means that opening it gives richer mixture and closing makes it leaner. If it´s located on the air filter side (between carb body and air box then is is air/fuel screw.And operates opposite: opening makes it leaner and closing makes it richer.