By secretsong on Unrecorded Date: Edit

I just acquired this motor and was wondering if anyone has any specs, info or advice about this engine. It was used in Evinrude-Johnson snowmobiles in the 70's...I heard this engine was very torquey and pulled strong from idle through redline.

By Kevin Percy on Unrecorded Date: Edit

I have a 2 Johnson 35 rotarys (still in the sleds). The roatary's are torquey, smooth and with the original exhaust fairly quiet. Keep the electric start if you can, make sure you have the engine compartment well vented,(the motor runs hot, and the exhaust on the sled glows cherry red after a 15 minute ride).
The spark plugs for that motor are no longer made (Champion UP77V), and they are the only ones that will work (they are a surface gap plug, a conventional plug will hit the rotor seals and you will lose all compression). Those motors had a problem with the brass shaft of the butterfly for the air inlet for the rotor chamber, in that it would wear out and break, then the hardware would get sucked into the rotor chamber (not a good thing). OMC did put out a replacement shaft (stainless I think) so you might want to check that before you go to the trouble of adapting the motor. They also had a terrible time with rotor seals wearing out. I would make sure the motor ran well before you installed it. I think you are stuck with the clutch that is on the motor (the stationary half is also the flywheel), so if your secondary pulley isn't compatible (the belt is approx 2" wide) you might have to adapt the secondary off the sled onto your Attex.

Not to scare you, but that's what I know.
Good Luck.

By Attex Bob ( - 63.93.96.61) on Unrecorded Date: Edit

Wow, thats very interesting!!!
I have no experience with this motor but I have driven a few RX7's in my time. Torque is not one of the Wankel's strong points. Ton's of HP, but not much torque. They don't have much leverage on the rotor. Like a piston engine with a short stroke.
Let us know how you like it when you get it in!!! I would be very interested in how it does!!!!

By Attex Bob ( - 63.93.96.61) on Unrecorded Date: Edit

Kevin, how many hours do you have on these motors? Are you getting used plugs for them? Are the rotor seals still available? Do you think you like them over a piston engine? Any other stories about them would be nice? Thanks again!!!!

By secretsong on Unrecorded Date: Edit

Thanks for the info, Kevin. Someone already told me about the throttle shaft problem...I'm a toolmaker so I'm not taking any chances and I'm making a new one. You are right about the clutch, though, and I'm not sure what to do with that yet. I also have a Sachs wankel engine that I've never tried but I might be able to use that clutch...think it's possible? Oh, I just realized what you are saying...I have to find a secondary clutch for my T-20 transmission, right?

By Kevin Percy on Unrecorded Date: Edit

I said I though it was torquey because I find the motor pulls well from a low RPM and accellerates well from a crawl. I find two stroke piston engines (in sleds anyway) don't pull very well until you get the revs up a bit.
I only run these a couple of hours a season, and am still using the plugs that were in them when I got them a couple of years ago. I have found a few NOS plugs at car flea markets. I don't know of any supplier for rotor seals other than OMC for these motors, and I think they stopped making them in the '70's. I like the fact that they are smoother than a piston engine, but they are not as easy to get parts for, you have rely on finding New Old Stock stuff. I don't know anything about the Sachs Wankel, other than they were used in Arctic Cat's, Alouettes, Skiroules (I think) and maybe one or two others.
I think you would have to adapt the secondary clutch from one of the rotary sleds to your T-20, yes, because of the belt width.

By demis on Unrecorded Date: Edit

i am trying to find a sachs rotary piston engine, also called a NSU-Wankel system type KM 37.
this is an 8BHP motor as was probably used in some lawnmowers during the 70's. if anyone has any idea of where i can find such a motor, or equivalent in size, small hp, would love to hear from them. i am conducting some experiments which could be very valuable to the next generation motors.