1982 ZZ750 wont run????

I have a new project,, new bike to me....,,, it's an 82 750 kz
I know these bikes are plagued with ignition issues... but im not sure if its a carb issue or ignition,,, or not.
****Unrelated I just tore apart the base of the engine to fix a starter clutch,,now its turning over great.*****
I tried to fire it and it would run for a few mins and rev up way too high then i shut it off,,,,, unsure what is up. Then i try to start it again...and it doesn't go, just a few sputters but never catches to run. I had a fuel overflow issue in the carbs a few weeks ago... but it doesn't seem to be doing that now. Im leaning towards carb issue but how do i test the coils for a good consent spark? When I pull the plugs i get spark but sometimes its not that good or weak looking but then it looks good.... maybe im not testing it right. Im just pulling the plug.. then putting it back in the boot and laying it on the metal engine and starting it to check the spark. is that ok?? Ir will this be weak because of the conduct with laying on the engine as apposed to being grounded well?

Also check you pick ups on your pulsing coil, located on right side engine cover, the pickups are located on the plate, there's two of them. Make sure there isn't any rust on the pick up, sand of rust with emery cloth or sand paper. If you haven't' cleaned or rebuilt carbs, do so. Might be pilot jets, clean out orifices and pilot jets. Pilot jet controls fuel from idle to quarter throttle

My bike did the same thing. Fired up record super high then I shut it off. Check your vacuum lines on the carbs and check your throttle cable. Wound up my throttle cable needed lubed and loosened a bit. That's just my experience with my 1983 kz750

Jsolonka89 wrote: My bike did the same thing. Fired up record super high then I shut it off. Check your vacuum lines on the carbs and check your throttle cable. Wound up my throttle cable needed lubed and loosened a bit. That's just my experience with my 1983 kz750

Yes ive checked the cable.. its fine. And throttle is in the closed position.

****UPDATE****
pulled the carbs, tore them down,,, cleaned them all up put em back on. and it fires up right away but will stay reving at 4000-6000 rpm till i shut it off.
I dont understand. Its running on all cly. really high. Thottle cable isnt stuck,,, throttle butterflys are all shut and operate properly when pulled open. Throttle cable adjustment set screw is backed off so its not even contacting the butterfly rods. I dont understand????
Am I missing something (carbs are keihin) I think all block off plugs are still in it? Vacuum hoses installed and working correctly.

Have you synced them?
Steve

i bench synced the throttle butterflys yes makeing sure they all open the same time,,, i didnt need to touch them they operated all fine.

Any time the carbs are done a sync is the final adjustment. One could be slightly off and will make it run high. You'll notice when you adjust that carb so it matches the rest, the RPM's will fall. You will reset the idle and do it again, blip the throttle and fine adjust again. This takes a while. The valves must be in spec as well as the timing with the advance working correctly. Carbs are the last thing on the list.
Steve

jcurriert wrote: . . . fires up right away but will stay reving at 4000-6000 rpm till i shut it off. . . Thottle cable isnt stuck,,, throttle butterflys are all shut and operate properly when pulled open. Throttle cable adjustment set screw is backed off so its not even contacting the butterfly rods. . . lock off plugs are still in it? Vacuum hoses installed and working correctly.

Symptom is often referred to as a "racing idle."

lock off plugs -- if referring to "anti-tamper" plugs, they are generally irrelevant to a racing idle.

Would suspect an air leak, whereby outside air is being sucked in, and which may also result from old cracked worn-out carb holders or a loose carb clamp or a cracked vacuum hose or an imperfect o'ring on the pilot mixture screw or carbs not pushed fully into the holders (and perhaps some others not immediately coming to mind).

If not already done, could begin by first assuring that carbs are pushed fully into the holders, and then assuring that all four carb clamps are snugly tightened.

It's okay to use silicone, Armor-All, or some other rubber-safe slick'm (maybe even KY jelly), to help seat the carbs inside the holders.

Good Fortune!

1- thx,,,timing advance ill pull off the cover and check it... if that was stuck on would it cause a really high rev?

Im sure that the butterflys are all closed during the high rev. When it starts it slowly revs from 4000 and goes higher and higher. What could I of missed when I cleaned it... is there a air ratio set screw or anything inbetween the throttle butterfly and the engine? How is getting too much throttle or fuel if the butterflys are closed?
2- If i tryed to adjust any carb setting with it running the way it is now,,, it would prob overheat and overrev and explode... it cant be run for more then a min currently.
If you see a good artical or vid on adjusting or checking the valaves let me know.. never dove into them before.
Thx
one sec i think i have a brain fart.......brb

A stuck advance could do it as well as leaks. You really should adjust the valves. They are the most neglected adjustment because they take time, work and a little money. Lots of threads here on that. Vacuum syncing is the only way to make all the cylinders run the same. Again, you need the gauges and that costs money.
Steve

Sounds like a massive air leak. The carbs must be properly sealed at the front to the head and at the rear with the airbox, with filter installed, before the bike will run properly.