TOPIC:

Hello, I recently replaced the fuel tee on my 1980 KZ440 after it started leaking. Now that it is in and the bike is back together it sounds like the left cylinder is either not firing or has a very weak combustion. I have also had trouble getting the carbs to sync after putting them back together.

Here is a quick summary of what I have done so far:

• pulled carbs out and installed new fuel tee
• cleaned out the jets
• put carbs back together and back on bike
• while syncing, found vacuum leak at carb boots. made sure carbs were seated, no more leak
• current state: will start with choke and idles at ~2500RPM. Idle and A/F adjustment does not seem to lower idle, only raises it
• while the bike was running, pulled off left spark plug wire, no change. pulled off right wire and it sputtered for a few seconds and died.

Last year I checked the compression in both cylinders and both were okay (can't remember exact numbers). I also adjusted the valves around that time.

Other than the fuel leak, the bike ran fine before the new fuel tee, so I am not sure what could have changed after the install (maybe its not getting fuel?). When trying to sync, the left cylinder ( which doesnt seem to be firing) also pulls the most vacuum.

How can I check to see if the carb is allowing fuel into the cylinder? Is there anything else I could try?

Here is a picture of the left spark plug as well. The right looked almost identical.

Thank you!

For the fuel issue, I just went out and drained both carb bowls, started the bike, and checked the bowls again. Both had fuel in them.

Leads me to think the issue is something else.

while the bike was running, pulled off left spark plug wire, no change. pulled off right wire and it sputtered for a few seconds and died.

sounds like your left spark plug cable is arcing to ground before the spark gets to the spark plug.
You can find it by running the bike in the dark and taking a spray water bottle and spraying a fine mist of water along the cable. The spark should be evident.

I did not have a water bottle but I tried lifting the cables off the frame while it was running to see if anything happened.

Oddly, now I can get the bike to start and idle at ~1000rpm when the right cylinder is unplugged. If I leave both cylinders plugged in then the bike will start and idle at about 1000rpm (left cyl only?) and then it spikes up to 3-4k rpm (when the right cylinder starts to spark?).

not sure if that would be solely a grounding problem or a carb sync issue. I replaced the ignition coils last year.

Are your throttle plates open the same amount at idle?
If you tried to sync the carbs while you were having issues, the throttle plates may not be matched in the amount they are open.
That may explain the rpm jump if the second cylinder suddenly came online.

You mentioned ignition coils in the plural. Are you running 2 coils or just 1?

uggggh
duplicate post

I am running one coil. The bike has two cylinders so that is why I used the pural.

When I was having issues syncing, I pulled the carbs and tried to eyeball the throttle plates since the vacuum method was not working. So they are close-ish.

If the right cylinder isnt firing at first, would that cause that cylinder to pull less vacuum? I was thinking if I waited for the right cylinder to fire and THEN attached the vacuum tubes, maybe I could get it to work.

Alternatively, why would the cylinder wait to start firing? could that be a spark plug issue or coil issue?