No spark under compression

They're talking about high voltage arcing problems at altitude where the atmospheric pressure goes to zero as compared to 14.7 psi at sea level.

Ok sports fans, on a given engine, the combustion pressure at cranking is roughly 80 to 150 psig. So that 's about 10:1.

That means that the voltage required to fire your plug outta da engin is 1/10 the voltage required to fire it in da engin at cranking rpm's.

So yus need to be chasing the elements of a weak spark.

So those who chose the coil, or the points, or condenser or whatever it takes to get 1/2 LI squared into the coil soas you can bang de plugs wins this round.

Mechanisms, mechanisms, mechanisms, stuff's caused, it doesn't just happen..... mechanisms..... ..

Nuf said.

• Harleys and more.

Now I believe those are two stroke motors that run either way for forward and reverse.

That being the case it may have two sets of points. Of which one set is used for each direction and switched for reverse after stopping. (a guess) or some other means of re-setting the timing by considerable amount to achieve this effect.

But anyway a fouled plug may fail to spark under compression.

A bad condensor can also make for a weak spark, so try that first, as it's a lot cheaper than a coil, or temporarily swap in a known-good used condensor.

Mark