1980 kz550 LTD super high rpm on start after rejet and mods

So I have finally decided to upgrade my 1980 kz550 LTD. I went with a Mac 4 in to 1 header, pod filters and sigma 6 rejet kit 100 main jets 37 pilot and 2 needle shims on the needles. Problem is that upon start up it revs to around 4K rpm right away with choke or no choke. Any suggestions?

That all sounds too rich in my experience. The Mac, if it is the reversing-flow type muffler (rather than the straight-through Kerker type) won't need much extra fuel for higher throttle openings. It will need a bit of pilot jet and needle shim, but I think you might be too rich overall. I'm not familiar with what actually comes in the sigma 6 kit.

Because they are mechanical slide carbs, you should be able to pretty much close the throttle completely. However, if you installed needle shims, there is a chance one of the slide holders is not seated properly. This could cause the other 3 slides to hang open and will prevent the idle adjustment from allowing the slides to close all the way.

See the TK22 site for details on how to properly shim the needles in a way that doesn't bind the needle clip and hopefully prevents the slide holder from binding in a crooked manor. Also see the section about setting the throttle stop position for 100% throttle. When you shim the needle, you alter the position of the slides relative to the idle adjustment and 100% open stop.

s3.amazonaws.com/gpzweb/TK22mainPage/TK22mainPage.html

I have removed the baffle from the exhaust so that it’s completely open. I checked all the slides before I put it all back together and they all seemed to be going up and down as they should. Only thing that made me scratch my head was that one of the doors for the choke was either bent up or missing. Could that make it run that way? Also could the float level make it run that way? I had the bottom covers off while cleaning it and could have bent them out of whack.

It sounds to me like your choke flaps are open too much at startup. Did you synchronize them?

Not sure. But the flaps are closed all the way when the choke is on besides the one that’s missing/ bent up. Picture is of the choke half way closed

You have to get that choke flap repaired so that it works correctly. Here is a website with info on your carbs.

gpzweb.s3-website-us-east-1.amazonaws.co...ge/TK22mainPage.html

The choke flap won't affect the throttle slide positions.
But the choke's fast-idle feature could if you are running with the choke on. When the choke is off (lever down) the fast-idle feature not applied.

Bottom line is, if the slides are closed, the RPMs can't run up, much less idle, unless there is a lot of air getting in through a huge vacuum leak while there is a simultaneous overflow of fuel in that same carb.

The most likely cause is a single slide causing the others to stay open, either through mis-adjustment of the sync or some mis-installation of the slide holders. It's even more suspect since we know there was shim installation done. Was it done with the method described in the link? Without that method, a double-shim is a high stack which will de-stabilize the slide holder during install.

If the slide holder is cocked, the slide can still go up and down smoothly, but the other slides just won't close all the way.

All you need to do is inspect the slides visually and verify the WOT position per that link (maintenance link). If they all are at the same height, then they should all be able to close when you unscrew the idle knob (which I assume you have been doing, as that is what controls the idle).

After I checked it out further with the choke just slightly on it starts up and runs like a champ. Going to test it out after I get my new headlight and tail lights in. Also have to take the center stand off since the new exhaust, the old bracket held the bump stop for the center stand. Going to just take the center stand off.

Yes, I take off the center stands as well, but keep them around as a very handy device for maintenance.