Sorry to interrupt the bike motor thread...
I just finished installing a 493 in my KBS Mk8 and thought I'd share
some info to save others the frustration I experienced.
After completing the installation I tried to fire the engine. It
cranked fine but did not even hint that it wanted to fire. I rechecked
all my fittings, connections, etc. Spark was good and there was fuel in
the carb bowls. I pulled the plugs and they were dry!? I pulled the
fuel line off the carbs and cranked the engine to check fuel flow. There
was plenty of fuel getting to the carbs. So everything checked fine but
it wouldn't run.
The 493 comes standard with a plastic "balance pipe" that connects the
two carb manifolds. There is a hole (1/2") in each rubber manifold that
the balance pipe connects to. When the 493 was first legalized, there
was discussion about whether the balance pipe was legal...I can't recall
what the current ruling is, but I don't use it because it does not fit
my installation (because of the way I routed the cooling lines). I
didn't have anything to plug the holes at the time and didn't think it
would have any effect on starting the motor. WRONG!!! If those holes
aren't plugged, or connected with the balance pipe, there is not enough
suction to pull fuel from the carbs into the motor.
I plugged the holes and the motor fired instantly.
BTW, this is the first 493 I installed that has Rotax reverse. Very
cool!!! Press the reverse button at idle and the motor almost comes to
a stop, and then very quickly begins running the the reverse direction.
The entire process only takes about one second to change direction.
-Jeff B.
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