The 91 mach 1 was a 617cc not 583cc,, I wouldn't worry to much about it until you have the 470 pulled out. The base for the rotary valve motors (the motor) are pretty much identical thus most likely the 470 motor straps will bolt on to the 617 cases.
Good for you, it should be pretty straight forward.

 

Thats news to me thanks for the info! Once my leg heals up here im going to drag the 470 to my garage and start. Everything seemed straight forward taking apart the mach 1. So if i just have to swap the mounts out it should be no problem. But what about the wiring harness, Ignition ext.. If I can avoid swapping all the electronics over that would be great.

 

Well I see the motor you took out came out of a RED PRS chassis if that is the case and its a 1991 formula plus the stock motor will be a 521cc Rotax. It's a bit challenging as Rotax made a Formula plus 521 and 580 and 583. I took a closer look at your motor pic and I would say its a 521cc as it doesn't have power valves (RAVE) and that is what 1991 Formula plus's came with.
Their will be some problems switching over as your 1991 is a PRS chassis and your MX 470 (1994) is a F chassis, so the motor will be pretty straight forward with engine plate, but the exhaust is different the air box is different and I'm pretty sure the CDI electrical (at the minimum) will be different as well. If you where going from the same chassis to chassis its simple but once you start switching chassis's it becomes challenging as you are changing engine size as well.

 

Yeah, I noticed that absence of the raves after reading around. I picked up the sled for a steal and the engine is in good shape and the 470 being down Im gonna try and make something work. I got all summer lol. Anyways here is a the Serial why I was lead to believe it was a 583. I can make the mounts but I can see the clutch being a pain.

 

That would be a 582 (just the 583 without raves). Came in the 1992 and 1993 Formula Plus. Damn good motor.

 

It sat for a few years pulled right over, 145 each hole to boot.

 

Based on the motor not having RAVE valves I''m pretty sure you can just bolt it in and go use the 580 carbs but you should be able to get away with the 470 pipe,, when you get it started check to see if the Tach works I believe you may have to change the tach to the Formula 1 tach (which is smaller in diameter, which sucks) so don't throw out the plus until you have the MX working as you may need to steal a few electronics off it. Hopefully its just a bolt and go, I switched out a lot of rotary valve motors of this era it was super easy. As Wildhang states the 580 is a very good motor and you'll be up about 10-15hp over the 470.

 

Very good! Thank you for the id! I am on pause right now everything has been stripped from the mach 1. Waiting for the leg to heal before i get the 470 over to my garage! I will keep everyone posted!

 

Can anyone else see it? :bc2: Why let good tubing go to waste?

 

Side project go kart. Using the mach 1 tube chassis for suspension and motor mount. Next step cut out the tubular frame mount to go kart frame or build custom idk yet. powered by 470 from a 94 mx secondary clutch from 04 rev 800 punched and keyed on a solid axle. Work in progress open to advice.

I don't mean to get off topic so if it's okay I'll post updates on both projects