1980 KZ 750 resurrection

Looking real good !! & I can see some black pin stripping in the future,
Pete

I cleaned and inspected the carbs, everything on the new set matched with what the manual called for (jet numbers etc.). I then installed them and started the bike up for the first time . The engine sounds good and appears to charge properly, shifted through the gears (didn't ride it yet) but I couldn't adjust the idle any lower than 2800 rpm.

I double checked the cable and linkages and they seem fine. I will check the carb boots later today. I have the factory service manual but it doesn't have a good diagram of all the vent and vacuum hose routing for it. Does anyone have a diagram showing where each port goes? I did plug all the vacuum ports so they wouldn't suck air but I think there may be something I am missing with these that may be part of my problem.

Did you bench sync the carbs?
Steve

swest wrote: Did you bench sync the carbs?
Steve

I did the bench sync and set everything to the book settings.

Thinking you set the idle screw too high and now can't lower it anymore.
Steve

A little more progress today. I have sorted out the vacuum lines and have everything going where it should. I loosened the boots, wiggled the carbs again and re-tightened the clamps. It still didn't idle right. I then looked at the spark advance unit and found my problem. It was froze up and needed to be taken apart, cleaned and re-lubed. And one of the weight springs was broken, fortunately I had another unit like that from something else but the springs were the same. It will idle right down now and seems to rev much smoother.

It now appears that the right two cylinders (3&4) are running richer than the left two (1&2) based on the exhaust and the black spark plugs on 3&4. I checked the compression and found 3&4 at about 120 psi and 1&2 were significantly less than that but had nice coloration on the plugs and nice exhaust which makes no sense to me.

I'm thinking I will need to check the valve clearance and probably make some adjustments. I checked the carbs, they were each adjusted the same but I still may pull them again to verify the floats are all adjusted properly and not leaking. Any other thoughts?

I was thinking about this a little bit more and I never opened the throttle when I tested the compression. With that in mind I think the carburetors for 3 & 4 must be open a bit more than 1 & 2 giving me a higher compression reading and also causing them to run richer than the other two. I will probably pull them off and check the bench settings again to make sure they are all closing properly.

Also looking at the manual it looks like there are some specialty tools to sync the carbs with a set of vacuum gauges, do you guys have/use these or have you made your own custom tools for this?

brokenspoke wrote: Also looking at the manual it looks like there are some specialty tools to sync the carbs with a set of vacuum gauges, do you guys have/use these or have you made your own custom tools for this?

This thread is the first one in the "tools" forum... www.kzrider.com/forum/21-tools/601385-carb-sync-tool#716301

I see that, I was also thinking that they show some specialty wrenches to hold the adjuster screws/jam nuts. I haven't looked to see if I can just use a socket wrench and screwdriver.

brokenspoke wrote: I see that, I was also thinking that they show some specialty wrenches to hold the adjuster screws/jam nuts. I haven't looked to see if I can just use a socket wrench and screwdriver.

www.amazon.com/Motion-Pro-Carburetor-Adj...0W66XHWG5YZR556GSSGX

Nessism wrote:

brokenspoke wrote: I see that, I was also thinking that they show some specialty wrenches to hold the adjuster screws/jam nuts. I haven't looked to see if I can just use a socket wrench and screwdriver.

www.amazon.com/Motion-Pro-Carburetor-Adj...0W66XHWG5YZR556GSSGX

I have one of those and it works very well. Ed