Back at it with the kz400. This weekend I wanted to start the official jetting process. Gotta take your time and do things in the right order and change one thing at a time. I struggled with the first part due to a few little hiccups stacking up.
First was the bike cut out on me a couple times. I didn't think much of it but usually out of habit the first thing I do is switch the petcock to reserve. No more cutting out. Of course I thought this was related to me messing with the mixture circuit and nothing to do with the fuel level because there seemed to be quite a bit still sloshing around when I cracked open the cap. WRONG. After parking and giving everything a once over I checked the tank again. Not empty but at the reserve line.
Next up was the fuel line fitment. When I first installed the line it was snug but after having some fuel and heat it started to swell just enough to not get a good seal which was causing flow issues. Stepped down a hair on ID of fuel line and now we are in business.
I decided to double check my timing with a light which drug me down another rabbit hole. On the left cylinder I get a beautiful light signal that grows with intensity to redline but on the right the light would break up a little and worsen to redline. I think this is due to polarity of the coil leads? Either way I swapped back to an old coil to double check, and confirmed it happens with both. Swapping caps didn't change anything and I think when the leads were swapped the issue changed sides. It took more time than I wanted to, but I felt like tinkering and getting everything solid.
Next up was a run down the road to check my mixture settings. I got about 5 miles out and felt some intermittent sputter. Decided to turn back for it to shut off on me. I could tell there wasn't spark but then out of nowhere it would start running again, get my hopes up and right as I was about to get on the road die again. Called the wife and had her bring the old coil, new plugs, etc. to fiddle with. Swapped plugs and thought I was good to go since they looked a little wet. I assumed it was just fouled on the right sight which has had a little more blue smoke from valve seal leakage(I think). Still didn't fix it so I decided to try and swap the coil back to an old one. That's where I found the culprit. One of the bullet connectors on the coil lead was way too loose and losing it's connection. I crimped it back tight with pliers and was good to go!
Mixture screw set 1.5-2 turns seems ideal so I decided to see where the needle settings would take me. I couldn't quite tell if I was rich or lean so I decided to move it down to the bottom clip and go rich first. The sputter I felt before was amplified by a million so now I need to lean it out. Moved the clip to the top and it's considerably better. Looks like I may need to lean down on the needle jet to an O8.
With the mid range feeling decent I thought it might be a good idea to run the same rich or lean experiment on the main. This time I decided to go leaner from a 180 to a 170 and it felt labored. Not like the fat rich feeling from the needle so I decided the safer bet would then to go to the biggest main I had available. Tossed in some 200 jets and it pulled considerably better. So I'm getting closer. Need to do some plug chops and top speed runs to confirm.
Current config:
6F9 jet needle - top clip (leaner side)
P0 needle jet - need to lean down a step?
25 pilot jet - may consider leaning down to a 20
200 main jet - may need to go up or down a hair
1.0 air jet
2.0 slide cutaway
2 full turns out on the mixture screw which is why I would consider leaner on the pilot
I also spent some time taking the MAJOR slack out of the cush drive system. Drivetrain takeup on throttle had a considerable delay and when I checked the "lash" of the cush drive it was about a 1/8" before engagement. See video below. I don't think they make new ones anymore, and after some reading saw mention of shimming the gaps with bike tubes. I got plenty of those and they did the trick! Much better now.
