As there was only one reaction to my post, it seems that only two of us have
this
recurrent kick-back problem. Based on old threads years ago, that is surprising.
That is why I repeat my message below:
Hi all,I am the unlucky owner of an engine (912ULS) which is prone to kick back
on cold starts. During the 6 years and 500 hours of operation I have tried
EVERYTHING
suggested by the Rotax factory, Rotax distributors worldwide and operators
writing on this forum, including the SoftStart module from Conair. All
these alleged solutions have had some positive effect such as a reduced
occurence
of the kick-back and a less violent one, but none of them, even when combined
together, managed to withdraw the kick-back completely.
Now the good news is that Rotax has introduced (at last!) new ignition modules
and a new flywheel hub to fix this problem (see SI-912-020 R4). The new ignition
modules do exactly what the SoftStart does: they prevent the ignition timing
to switch to the 26 degree before TDC as long as the starter motor is activated.
In fact the switching to 26 degrees occurs a few seconds after the starter
button is released. The new flywheel hub features extended trigger cams giving
a 3 degrees after TDC ignition timing during the cranking phase instead of
4 degrees before TDC. Obviously the engine cannot kick back as long as the
ignition
happens after TDC, so I strongly believe this change is a radical solution
to the kick-back problem. I do not need the new ignition modules as I already
have the SoftStart. So I will replace the flywheel hub only.
Here are my questions:
1. The price of the new flywheel hub is 315 Euros, French VAT included. To avoid
spending that amount, I am thinking at modifying the existing hub. I would weld
a 7 millimeter extension to the trigger cam trailing edge and machine it on
a lathe or adjust it with a file. It is not necessary to modify both cams as
only one is used with the SoftStart module, the other one being inactive during
the cranking phase. Does anyone know what material (presumably a variety of
ferromagnetic steel) the hub is made of? Any suggestion on how to do this cam
extension?
2. Removing the flywheel hub is very easy, even without removing the engine from
the aircraft. But a special tool is needed to extract the hub from the
crankshaft
tapered end. This tool (Rotax P/N 877377) cost 76 Euros VAT included. This
is not very expensive but is too much for a tool I intend to use only once!
Does any one have this tool available and would lend it to me? Are there many
other owners who want to do this mod? If yes we could ask the Europa Club to
purchase the tool for use by the members.
Waiting for your answers
Regards
Remi Guerner
F-PGKL
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=323536#323536
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