Revving high between shifting

I have an 81 KZ750 that I just got back on the road, and everything is running pretty well, except when I let off the throttle to shift. The rpm's take a while to decrease after I let off the throttle, and I usually need to wait a second or two after letting out the clutch before I give it any more throttle.

It's not really that big of a problem, but I'm just wondering how I would fix it so that the rpm's drop as soon as I let off the throttle. I checked the troubleshooting section of the owner's manual and it didn't have anything that seemed to address this issue — probably something too obvious to even put in the troubleshooting section!

thanks for any help you can provide

Chris

Some possible reasons:

1. Air leake on carb boots?
- Spray some starter-spray on carb boots when idleind. If it affect engines run there´s an air leake. Get new boots from for example Z1 Enterprises
2. Throttle cable too tight?
- There must be a little loose on the cable. Otherwise throttle will stick. If you have 2 cables there should be only very little loose between thos 2 and the one pulling slides down should be tighter.
3. Idle screw set just a bit too high?
- This will make revs stick a bit. Run the bike hot and adjust idle at 1.000-1.300 revs.
4. Running too lean on idle?
- Are the carbs clean, synchronized and tuned?

I would also check cable routing, make sure there are no sharp bends in cable(s). Check cable ends to make sure there is no rust of fraying and finally when is the last time you lubed the cable(s)?

You may also need to check that the mechanical advancer inside the timing cover rotates and returns freely. The advancer not returning freely could cause the revs to hang momentarily.
A light spray with WD40 or some dielectric silicone oil should free up the mechanism.
Grant.

Hi, Chris. I had the exact same problem on my 81 KZ1000, and it turned out to be a carb sync issue. As soon as I synchronized the carbs, the problem was resolved and never reocurred. I use the Morgan CarbTune.

My kz1000 also had this problem. Went through it today and found out i just had a gummed up throttle cable.

Grantl wrote:

You may also need to check that the mechanical advancer inside the timing cover rotates and returns freely. The advancer not returning freely could cause the revs to hang momentarily.
A light spray with WD40 or some dielectric silicone oil should free up the mechanism.
Grant.

I had that one! I removed the advancer as per manual, and lube everything good with some wheel grease, slipperier the better.

Cheers.