On Jul 25, 9:20*pm, "Bill" wrote:
I have a 10.5 hp gasoline engine on my wood splitter which sometimes kicks
back when I pull the rope to start it. (Just once every few days, but that
is once too many times.)

This kicks back with a lot of force! And I am pulling with a lot of force as
well! Not good. (I've noticed this same problem with smaller engines too,
but not so much kick back force, so no problem there.)

I got to thinking that I was going to break or injure my hand/arm if I kept
starting this engine. I searched the internet for injuries from starting
these larger engines and there were in fact quite a few injuries including
some broken bones. So I decided to solve this problem by installing an
electric start. No more problem now for me...

But I got to thinking about this and why this happens. And could something
be done to prevent this? (And the reason I am posting this.) A lot of you on
these groups are quite clever, so maybe someone can come up with
something...

I think the problem is that the spark is firing right when the piston
reaches the top of the stroke or slightly before it reaches the top. Then
sometimes this will cause the piston to go backwards instead of forwards.
(And it needs to be this way of course to run properly.)

My idea is to delay the spark just a little for starting. There could be a
switch to start an engine which delays the spark. Then once the engine is
running, you would flip the switch and it would spark and run like normal..
But when starting, kickback would be impossible because it would not spark
until the piston was its the way down.

Anyway I thought I would pass this idea along. Maybe some rocket scientist
out there could come up with something which would attach between the spark
plug and the spark plug wire???

Maybe the timing is off from Pin Shear