Need help - high idle - 81 KZ750 LTD

Hello all. I'm new to this forum as well as new to an owner of a KZ.

I discovered this website/forum while endless browsing the net in search of some help. I think I found the right place, as everyone seems very knowledgeable about KZ's around here.

Here's my story.


I have an 81 Kawasaki KZ750 LTD. I'm having problems with the idling ONLY after I've been riding it for a little while. When I start the bike, the idle is fine. I'm aware of the idle knob, but that doesn't seem to effect my problem.(Also, what is the ideal idle RPM so I can set it?)

After riding around for a little while, I'll come to a stop sign/light, and when I shift down to 1st gear(and have the clutch pulled in) or put it in neutral, the idle is really high - somewhere in between 3500-4000 RPM. Remember, this is ONLY after riding around for a little while, NOT when I first start it. For instance, I'll pull into my driveway, park the bike while it's running, and the idle will be really high.


I purchased the bike a few weeks ago, the guy I purchased it from declared it had been recently tuned up; carbs cleaned, spark plugs, oil change, etc. I believe the bike was sitting a good while before he cleaned/tuned it up.

Anyone have an idea of what my problem is?

I have not ridden my bike in almost three years so I am no expert but . . if I remember right you just have to adjust the choke after it warms up.

Welcome to the site dankest.

The idle should be set at about 1300rpm and you should set the idle when the engine is fully warmed up. You start the bike using the choke and as the engine warms you reduce the choke. I'll start using full choke, put on helmet, reduce choke a tad, ride to end of the street and reduce the choke to half. By the end of the next street I can switch the choke fully off. Another 5 min and at the first set of traffic lights the bike should be idling at 1300rpm.

If that's not working for you then likely causes are a sticking throttle cable which may be tight or kinked or maybe needs a lube or else an air leak somewhere around the carbs.
Good luck

Post edited by: JR, at: 2007/07/23 10:16

Welcome to the site. You will find a lot of good information here.
I also have an '81 KZ750LTD and I experienced a high idle same as yours. My problem turned out be an intake leak where the carbs plug into the motor. The rubber was not providing a good seal. If the person you bought it from removed the carbs to clean, this could be your problem as well.
You can test this by spraying WD-40 (which I had no luck with but have heard that it will kill the bike if there is a leak) or starter fluid which will make your engine rev if there is a leak (worked for me).
Also, you need to check the throttle cables for proper routing and ease of movement. There is emissions equipment that can leak as well if still in place and not in good shape (it is easy to remove).
Good luck.

I keep forgetting that you guys south of the border got that emmissions tubing and stuff on you rides.

Dang, I already love you guys. lol


I'll go through each troubleshooting advice and see where that leads me. I'll be sure to keep you guys posted.


Thanks a million!

what ended up happening with your problem? b/c my '80 750 LTD does the same thing. I've isolated the problem to the throttle assembly. The throttle cable itself will go lax but the actual throttle connected to the carbs doesn't fall back down all the way(if i push it down with a screwdriver the bike will go to its normal idle).

my money is on the 3 screws that seem to be adjustable (throttle stop screws?) that connect the throttle to the carbs, they have a spring around them and are in some threaded housing.

anyone have any tips for the proper way to adjust these?