any KZ gurus out there?

[oldschoolsdime92]

I have been working on a buddy of mines 77 kz650. Mostly stock other than a mac header and exhaust. I can't get the damn thing to idle right. I will get it to idle nice and smooth, and as soon as you rev it, sometimes the RPMS will just hang around 4k and then idle back down. other times its nice and crisp. The next issue im running into is, I will get it idling nice around 1500, and then the idle will slowly drop to 1000, and then it starts getting rough and acts as if it wants to die and sometimes will if your not quick enough on the throttle. anyone have any thoughts?

[ReconRat]

Lean fuel, either in the fuel feed to the carbs, in the carbs or it's the timing (cam timing also, like off time with the cam chain.)

Although the "die from an idle" is more of an idle fuel flow, and is often a vacuum leak between the carb and the engine.

By the description, it's the quantity of fuel flow when off idle. So that's either the amount of fuel coming from the tank, or it's one or more carbs, in the needle jet mid-range flow, or the main jet high-range flow.

I would actually take the fuel filters or screens out first, and clean them. Even take the hoses off, and clean and check them. The service manual should say how much fuel will flow in a certain number of seconds, when draining some from the tank. Each tank fuel feed hose should do that. Look for rust inside the tank.

Odds are that the carbs well need to be cleaned and/or re-adjusted. Air leaks around the intake manifold will sometimes go away temporarily if water is sprayed around the joints till the air leak stops.

[Strictly Street]

Other thoughts.

Idle problems on my 1980 KZ were helped by.

New spark plug wires, which caused me to also find that the wires weren't seated properly.

Low voltage on the coils, which is an issue for all older bikes. See this thread for info;

http://www.wgcarbs.com/forum/index.php?topic=263.0

A lot of good info there for "Vintage Bikes"

Between those two issues I got the bike running 40% better.

Lost a high speed miss, an idle issue and it became a much better behaved bike.

Starts quicker, jumps higher etc.

For carb issues see this guide:

http://www.factorypro.com/tech/carbtune,CV,high_rpm_engines.html

and this one:

http://www.kawasakimotorcycle.org/forum/vintage-motorcyle-info/103856-kz550-rough-running-float-height.html

Hope this helps.

[oldschoolsdime92]

so far you guys are a ton of help! thanks!

[Strictly Street]

so far you guys are a ton of help! thanks!

Glad to be of help.

I think that Recons comments are the ones you should try first. It's a more general solution so it's more likely to be true. Especially on a 1977 bike.

But if you have good fuel flow, take a look at those plug wires.

If they are not seated properly or arc/short out you get some real weird results. Like that strange come-and-go idle trouble you are having.

If you have to replace the spark plug wires you will find that nobody has them for less than a bajillion dollars for a bike that old.

So try NAPA part# 780310, you will need 4 of them ($5 each). I happen to have just done this mod to my 1980 KZ so I still have the NAPA box/P#.

One end has a spark plug fitting the other end you wont need.

Cut off the connector you don't need and push the wire into the coil tower so the little spike pokes into the center conductor.

Oh! make sure to put the twist on caps back on the coil wires to hold them securely in place.

Hope this helps.

Edited June 27, 2009 by Strictly Street
add info

[oldschoolsdime92]

excellent. Hes not wanting to put much money into it, as hes in the works of getting a triumph speed triple 955

[ReconRat]

I second the plug wires. Eventually they go bad or poor and need replaced.

I actually had one fall off, that's how I could tell it was no longer working, heh.