Jonathan,
I was unfortunate to have one of those engines prone to kicking back and have
been
trying everything possible to fix it over the years: new battery, battery
moved forward to shorten the cables, preheating when cold. These provided some
improvement but did not fix the issue. Then I installed a Soft Start module and
the new flywheel hub with delayed timing. Then I had to replace the ignition
units with the last version with integrated soft start. This again provided
a great improvement but there were still an occasional weaker kick back. I
finally
replaced the sprag clutch (that was 3 years ago) and then the problem was
completely solved.
I asked myself the same question as you did: Why should there ever be any
kick-backs
at all, even with a tired battery, as there is no spark possible before
3 degrees ATDC while starting? I do not have a sure answer but I believe what
we then perceive as a kick back is not a kick back. It would call it a
kick-stop:
during cranking, the sprag clutch slips occasionally, then the prop stops
turning for a fraction of a second, giving the false impression of a kick back.
However this situation will not last long, as these repeated quick-stops will
for sure accelerate the damage to the sprag clutch, ultimately causing a
constant
slipping and preventing to crank the engine.
One thing is sure: with an engine fitted with the delayed/retarded ignition
system
and an undamaged sprag clutch there is no kick-back nor kick-stop at all,
even with a very weak battery.
Remi
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=487874#487874
|