Engine revving out of control with throttle closed

djturnz wrote:

...Looking at my top hole, it is slotted. Is this an adjustment? Like, if I don't get it just right when I put it back on, my timing will be off or something?
The other two holes don't appear to be slotted at all, so I can't imagine it could ever be too far off, but I'd rather know now, that after the fact.

It's okay to just ignore the slotted top hole.
Timing on this oem electronic ignition is permanently set, and not intended for any later adjustment.

The ignition timing may be verified with a timing light while the engine is running, which is to assure proper functioning of the advancer by watching the F mark align with the case mark at idle, and seeing the "II" advancer marks align with the case mark at higher rpm with increased throttle.

If the advancer is malfunctioning, it sometimes needs lubing, or both cleaning and lubing, as already suggested.

Good Fortune!

Motor Head wrote:

It can only go back on in the same spot, you can always make a mark on the plate and case where it was if it bothers you.
Did you try to turn the advancer? It should move freely with only the 2 springs as resistance, then move back smoothly on its own.
Do you have a good service manual?

I have not been with the bike since my post last night, so no, I have not tried to turn it.

I have been holding out on a manual. The previous owner said he had one, but couldn't find it. He said he would call me when he did, so I have been putting off buying one.

There are some links here in the forum, for downloading a .PDF version of some manuals.
TEll everyone your year/ model and it will appear!

Try this for a .pdf manual:
www.metrovationinc.com/christemple/KZ750.pdf
It should be pretty close and have what you need.

Illustration of view without the round backing plate.

Thanks. Someone posted me a link for a scanned PDF of the manual in a different thread. All the pictures are very dark, and some of the writing doesn't always line up with the next column, but that is what I used when I was refrencing my wiring and stock specs. I haven't tried to use it for more than that.

I probably won't get a chance tonight, but I'll get into the advancer this weekend for sure.

I REALLY hope that is what it is.

Thanks guys.

I did state that my carbs were very clean inside. I forgot to mention that on 2 of them, when I pulled the top plate off, the plastic cylinder was a little tough to remove. When I did, I found black residue on them. It flaked a bit like paint. I removed the flaky stuff and when I went to put them back in, they fell in (meaning, there was resistance getting them out, but none going back in). Was that carbon?

[Click on image to enlarge view.]

It's generally unnecessary to hand turn the crankshaft when using a timing light to verify ignition timing and proper advancer function.

Hand turning by using the 17 mm nut is used when dealing with cams, etc. to align the T mark with the permanent case mark for "top dead center."

The T mark is irrelevant incident to ignition timing and advancer function. Sometimes the T mark is erroneously used and mistaken for the timing mark. :pinch: The "T" is Top dead center, NOT timing. The "F" mark is for ignition timing.

Good Fortune!

I had a couple minutes last night to look at it again. I ran into another snag though. The screws that hold the ignition plate on seem to be very soft. Two of the three started to round out the phillips head almost immediately, with very little pressure from the screwdriver.

I did fire a shot of penetrating oil through the witness hole onto the advancer.

Very difficult to work on a bike without a "IMPACT DRIVER".
You should buy 1, the bit is the part you want to spend some money on as the cheap ones break easily. I suggest a Harbor Freight Impact Driver and Snapon couple of Impact Bits. Otherwise you will round out more screws. In the mean time, if you have a good punch, with a small tip, put in the phillips center, and smack it hard a few times, this will loosen it most likely, or a chisel along the head of the screw in direction of rotation, anti-clockwise. If not get out a drill and drill the head off, then replace the screw, preferably with a Allen cap head. Righty Tighty & Lefty Loosey.

Sorry to divert away from the ignition topic, but have you checked to make sure there is some slack in your throttle cable when at idle? The adjustment on mine is at the lower end of the outer cable, just above the carbs. At one time, I had no slack in my cable, and when sitting at idle, if the handlebars were turned away from center the engine would rev to about 4,000 RPM until turning back to center.

Just thought you may want to check this if you have not already done so.

I am going to harbor freight tonight, so I'll look at the impact drivers. I assume you mean the kind that looks like a torque driver and you hit the back to make the bit turn?



Yes there is slack at the carbs. I am going to need a new cable though. Which sucks because I was reading in another thread that the cable for the 82 KZ750 isn't available, though I don't know if thats the LTD cable or the standard cable.

My adjuster at the carb end (threaded stud piece) doesn't spin freely from the cable sheath. When putting my carbs back on, I had to spin the carbs to screw it in. There is slack though.

The wild revving at idle has stopped now. But it still seems to want to hang in RPMs when I clutch and release the throttle, it just wants to hang there for a few seconds. It does it when I release the throttle and pull the clutch and just coast. The RPMs will hang at whatever I leave them at for a few seconds, then they start to come down. Even idling, if I blip the throttle and let off, it comes down slowly.

I also noticed that I must not have my right side muffler "slipped on" all the way, because I can feel some exhaust pulses at the clamp location. I don't think it's related to the revving, but I did notice that last night.