rotax 643 (617) motor

[extremsledder]

so i have one of these motors from a 92 mach 1, and i dont really have any expirence with the rotary valve motors so my question is what can be done to get the most from this motor, like pipes, porting, head shaving, oil injection delete, things like that o and also its going to be put in a 89 or 90 650 chassi so if any body wants some 650 motor parts i have some for sale

 

[Reeb]

Call Robin's Marine/Sled Service in Kamloops. He raced these for years and had some good experience with them. 250-320-0083

 

[extremsledder]

also dose any one know what has to be done to remove the oil injection from one of these rotary valve motors
thanks

 

[DWHalverson]

Take off the RV cover and split the cover to get to the oil pump gear. Take that off and then pull out the oil pump, build a block off plate. Now the RV shaft and gear needs to be fed oil. A few different ways to do it but, I always used a clear hose and ran it from the bottom nipple in the case up to the nipple in between the cylinders. Here's the key. Do not fill the hose full. If you do it will blow off. If you fill it and run it you may see some drop in the level in the hose. Generally it's from working all the air out. If you need to add oil, pull the top of the hose off and squirt some in slow. All this does is circulates oil for the RV shaft cavity for the bearings and gear. This does not feed the crank bearings oil!! You will still need to premix your gas. Hope this is clear enough, if not I can explain it better if you have any questions.

Dave

 

[extremsledder]

yes thank u that clears things up i figured that the shaft would still need to be oiled but was unsure on if it was to complicated to do

 

[extremsledder]

so i have a few more questions bout this motor like pipes and if a set from say a 583 or 670, and what elth can be done to get easy power from a rotary valve motor?

 

[extremsledder]

ttt

 

[d&mraceengines]

617

i used to run a 92 mach 1 mine had mach1x pipes 44mm carbs ported a cut rotary valve and heads welded and reshaped for more compression this engine ran awesome and was very reliable a mach 1 x was a 670 so you should be able to run a 583 or 670 pipes that fit an s chassis ski doo in your polaris since you are in canada i would contact jaws for pipes there pipes work really good on rotax engines depending on the elevation you run you might want small volume pipes and the 40 mm carbs thanks and have a great day

 

[extremsledder]

ok thanks for the info