"Don Young" wrote

It is pretty unlikely that your ignition system is
bad or off tim;ing, but the suggestion to try a new spark plug, even if
the present one is sparking, is valid.

Don Young

I had a guy come to do some concrete work. He had a nice mechanical trowel
with a Honda engine. After pouring the concrete, they couldn't get the
trowler to work. He gave up and started to trowel it by hand, which was
1,000 sf.

It had spark, it had gas. I poured a little in the intake. No luck.

I went and pulled a Honda plug from my mower, and it was a match. I put the
plug in, and it took off on the first pull. The guy was just about in tears
thanking me. The concrete came out okay.

Always keep a couple of extra plugs. You can mess with them and clean them
up with a pin in the recesses of the parts on a cold winter evening. But
when it's GOT to run, it's nice to have a quick replacement that you KNOW is
good.

Steve