K301 intermittent misfires
 

My recently rebuilt K301 is suffering from occasional misfires. It has about 3 hours on it now, I'd guess.

It runs pretty good, and I'm pretty sure I have the carb adjusted correctly.

When it's running, idle, half, or full throttle, there are times where it will miss one or two strokes, and then run fine again.

At first I thought it might be valves seating, but now I'm not so sure.

Anyone have any suggestions on what to try?

New Kohler points and condenser. Timed with a multimeter to see points open right at the mark.
Aftermarket coil. New. Internal resistor.
NGK spark plug (I thought I ordered Autolite, but the supplier and I have a disagreement on how a description should read, or be read).
The plug is gapped per the manual, 030 or 035? (I forget what exactly).

It acts like it just didn't get spark on one shot, then recovers. Happens maybe once or twice every 1 to 5 seconds, never really goes away. This is annoying as heck, especially with a new rebuild!

Help?

Thanks,

Jim

If you are sure there is no short in any of the wires or ignition switch or plug wire or plug...those are easy to examine and relitively cheap to replace....then I suspect a bad coil.

Scott


edit-

If it misses consistantly....you know it's going to miss....then I would hold a test light on the positive side of the coil....if light does not flicker when it misses then there is nothing wrong with the power supply (wires, switch) and it has to be points or coil or plug or plug wire.

Is the condenser grounded well? When you repaint an engine, all the ground connections get messed up unless you mask off spots here and there to keep all of the sheetmetal and everything attached to it grounded.

Well, I just changed out the plug. It appears to have been the problem.
It was gapped at 30 (my bad), and I gapped the new one at 35 per the manual.
It was somewhat fouled from oil.
I'm thinking it might have been from the break in, the rings aren't seated yet. It does puff a bit of smoke, but not bad. I guess a little oil goes a long ways, especially when it comes to fouling a plug.
I'm still going to try to find some autolite plugs. What's the number again? 316?
Thanks for the recommendations! I watched the voltage via a light, no change. I checked for a bad connection at the coil or condensor, things were good. I guess I know all the other stuff is good now, I'll just swap in a new plug if it starts doing this again. It sounds a LOT better now!
Jim

Autolite 216. Off the top of my head, correct if wrong!