Our Clark GCS30 with a Mitsubishi 4G54 motor had been starting and running poorly for some time and we only use it intermittently. It finally quit and would not start. I put a Century C-RK-J 3 kit in the regulator/vaporizer according to instructions and a diaphragm in the mixer/carburetor. I carefully cleaned all components, although I didn't open or disassemble the governor only cleaned the bore. I also put a new distributor cap and rotor on along with liquid and vapor hoses plus a filter which was absent previously. The vacuum lockout had been replaced with a solenoid shut off and although it seemed to be functioning I pulled the plunger for the time being to be sure I have fuel.
I cranked it with great anticipation, but there was no joy in forkland on that day.
I had to adjust the governor (inner) screw to get it to run at all after the rebuild and it needed 2-3 turns to get it to quit hunting, I did not adjust the outer nut since the rpms don't seem excessive although I haven't put a tach on it yet.
It won't start without pressing the primer button, but starts every time and runs excellent at middle to high rpm with great throttle response but dies at high idle. If I hold the primer button partially open it will idle, so it seems to be lack of fuel rather than a flooding situation? There is no spitting, sputtering, or coughing, it either runs or dies so I don't think it's spark/timing related. I tried running the idle air screw all the way in with basically no change. I used a minimal amount of silicone gasket sealer on the carb/governor bodies as there weren't gaskets in the kit. Then I checked for possible vacuum leaks with soap water spray.
One possible fly in fuel line is that for some reason there was a VERY similar spring (same wire size, diameter and coil, one is only 1cm longer) on the work bench when I was putting the C-J kit in. There was not a new spring in the kit and I have no other regulator that it could have come from, just an odd ball spring from some other project. Neither has a blue or orange color to them, although the one I didn't use was a stainless steel color but it's magnetic. So I put the shorter older looking one in, thinking it looked used.
Any suggestions where to go from here would be appreciated. I'm thinking the governor adjustment is making up for a problem somewhere else, but it sure does run well this way.