Snowmobile engine swap

turbosundance

I thought I would post some information about my snowmobile engine swap in my 90 Marathon. My cart used to have 244 3PG and I've swapped it out for a 1975 Rotax type 434 440cc snowmobile engine. The new motor redlines at 9000RPM and makes 42HP with the stock tillotson carb and expansion chamber exhaust. I have replaced the Tillotson with a 32MM Mikuni carb and the exhaust will be a simple setup using a automotive muffler. For testing I have a cheesy old snowmobile can muffler installed to keep noise down. So far the thing runs but I'm having a problem with the motor tunning too hot and running on one cylinder and eventually stalling once the motor heats up. I need to do some carb tuning because I believe I'm running too lean right now and overheating the motor. I no longer have reverse but I don't mind.

turquoisterror

Where did you get the HP and RPM info for that motor? I am also looking at putting an old rotax that looks about exactly like this in my G1 Yamaha and I was looking for some specs. Also, do you know anywhere to buy rings etc cheap for a rebuild? Does the Mikuni cab make a big difference? Thanks.