Bill,
You're asking the wrong guy for technical explanations. I can turn a wrench but usually need someone to tell me which way.
All I can tell you is:
- the motor must be equipped from the factory with reverse. The main ingredients that differentiate a reverse vs non-reverse is an extra set of pickups and a different MPEM ignition module. You can identify a motor that has reverse by looking at the wiring harnesses. All 493 motors have three wiring harnesses coming out of the motor. One has a triangular connector, one has a round connector, and one is rectangular. If the harness with the rectangular connector has 2 leads it is NON-reverse. If it has 4 leads, it has reverse.( I believe that the motors that Tony Murphy sells are equipped with reverse) - I believe that sleds equipped with reverse have different clutches but I'm told that regular clutches will work as long as you don't use too much throttle in reverse mode. - To activate reverse, you press a button which supplies a momentary ground to the MPEM. To go forward, just press the button again.
-Jeff B.

Jan Schmidt wrote:

Jeff,
Can you give us a technical expaination as to how that reverse thingie
actually works?
Inquiring minds want to know.
Bill Schmidt 88 red devil kawi (no reverse)

Jeff Blumenthal <[EMAIL PROTECTED]> 08/26/06 9:51 AM >>>
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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