-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of David
DeFord
Subject: Europa-List: bad cold starts
--> <davedeford@comcast.net>
When it was new, our 912S started as prescribed by Rotax when cold,
i.e., full choke with throttle fully closed. Opening the throttle even
slightly would kill the engine, whenever the choke was applied. Over
time (400 hours), it began to need just a bit of throttle along with the
choke, in order to start. Now it runs very roughly on a cold start with
full choke, and will die after a few seconds of this (if we can stand
it) unless the throttle is opened more than 1/4 inch. It then runs
perfectly smoothly, from idle to full throttle, without the choke.
Unfortunately, opening the throttle this much causes the shaking to
become so violent (momentarily, until it becomes suddenly smooth) that
it typically dislodges the muffler from exhaust header pipes. It starts
just fine without the choke, once it is warm.
Please don't bother to suggest balancing the carburetors, which we have
done very precisely (witness the very smooth running without the choke).
We have partially disassembled the carburetors and cleaned all of the
jets with carb cleaner (though there was no sign of any contamination or
blockage). Mag drop on both sides is fine, compression is like new, and
we have never experienced any kickback on starting. We have searched in
vain for any vacuum leaks, and the float needles seem to be keeping the
float bowls filled properly.
We feel that we have exhausted all of the reasonable possibilities, and
so are open to bizarre and unlikely suggestions as well at this point!
Dave DeFord
N135TD (monowheel XS, 912S, Airmaster)
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