Troubles

My engine that has run well for about 3-400 mi.
It started skipping and a little backfiring. Sometimes it would run fairly well then start skipping or not run at all.

Checked the plug it was burining a little lean. Changed plug and wire with a known good ones(no change).

Checked wiring connections including magnito ground(looked good).

I thought it might be a fuel filter problem. Changed the filter(no change).

Next thought CDI!(wrong) As I was changing the CDI, I saw a tiny wear mark on the brake sw cable.

It had vibrated and worn thru the insulation on a bracket. turns out that was the problem.

I hope this might help someone when they are experiencing similar symptons.

I would assume it would be due to the nature of the wire vibrating and grounding. 1. late ignition, at the very end of the ignition cycle and the unburned fuel buildup in both the exhaust port and exhaust.

So all I can say is experiencing it is believing it. Once the wire was taped the problem went away 100%

Jim

PS: The first thing I did was check for a fouled plug that could have caused late detonation, but it was clean.