Hi Richard=2C
I had all the same problems as yourself and others. As I understand it the
re were a number of reasons:
Early 912S production engineHigh compressionLow torque starter motorOrigina
l flywheel not giving the correct ignition sequence on startupFriction torq
ue in slipper clutch at the low end of permissable range.
I changed the starter a long time ago and it was a big help=2C but only a s
ticking plaster.Pre-heating the engine worked as well.
But the occasional vicious kickback was wearing out the sprag clutch and th
ings would get worse.Sometimes it would start but seemed to run on only one
cylinder for a couple of seconds.
So=2C I took it to the Rotax agent and he seemed to know exactly what was g
oing on. The engine was removed completely=2C sprag clutch replaced=2C and
at the same time the new type flywheel installed. Gearbox was removed and t
he 3 worn spring discs in the slipper clutch were replaced and the friction
torque set to the maximum. With the gearbox off=2C I also had the oil seal
at the rear of the box replaced=2C and that was no easy job. I always had
a tiny oil leak from there since new.While the engine was out=2C we also re
moved the two mounting frames=2C had them sandblasted=2C professionally ins
pected=2C and then powder coated. I also did a thorough cleaning and polish
ing job on all components=2C especially the exhaust. Made some wiring chang
es etc. etc.
Re-installed everything and tried a start. It started instantly=2C then I s
ynchronized the carbs. The engine starts nicely every time. Not only that
=2C but it also stops more gently. The Rotax man turned the donkey into a r
eal pussycat.
The bad news is: it cost me $ 2600=2C incl. 13% tax. That was for 20 hours
labour plus parts.
You may want to just change the flywheel=2C which you may be able to do you
rself and without removing the engine completely. The wear on my clutch was
tiny=2C but enough to cause the problems.
Hope you get it sorted.
Cheers=2C
Karl
> From: riddon@sent.com
> Subject: Europa-List: 912S sprag clutch
> Date: Sat=2C 1 Sep 2012 10:01:46 +0100
> To: europa-list@matronics.com
>
>
> I often have a bit of a problem starting my 912S when it has been stopped
for while but is still just warm. I was at the rally yesterday and it too
k me longer than normal to start the engine after about 4 hours stopped. Lo
ts of kickback etc. I tried on one mag=2C both mags=2C with throttle=2C wit
h choke and no throttle. I have a fairly new red battery and the larger sta
rter motor. I wondered if the sprag clutch is starting to fail? Engine has
done 650 hours. From those who have already replaced their sprag clutch=2C
what are the symptoms and at how many hours?
>
> Richard Iddon
>
> G-RIXS
>
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