Building a 670 - Snowmobile Forum: Your #1 Snowmobile Forum

summit_rules · 03-17-2007, 12:19 PM

Hey everyone... I'm debating what to do about my seized up 670 in my '94 Mach 1. The previous owner of the sled said that the main bearings were letting go, so I'm assuming that's why the engine seized up on me. But, to be honest, I don't know for sure. I haven't had anytime to tear apart the engine (that will be a summer project). But I'm trying to do a little research right now so I can start buying parts. So anyways, one of my choices would be to rebuild the 670. Some people are telling me to look for another engine because it would be cheaper? Either way, as much as I liked the engine, I want more power!! While I'm rebuilding the engine (or buying another engine), I was hoping I could do some modifying. So, what kind of build can I do with the 670? Is there a large aftermarket for this engine? What are your recommendations!! I've heard good things about the engine, that must mean there's lots of hidden power there!

**smallengineguy** · 03-17-2007, 06:17 PM

There isn't a lot you can do with the rotary valve 670's. Clutch kit will be the most bang for the buck.

Brownie45021 · 03-19-2007, 09:49 PM

I would opt for another motor. I would recomend a more up to date 700. If you can make it fit it would be worth it. These newer 700's make lots of power and offer a large aftermarket like u want

summit_rules · 03-25-2007, 07:56 PM

Hmmmm... What specific motor are you talking about??? And, will it drop into my sled? How much custom work am I looking at here?

**smallengineguy** · 03-25-2007, 08:11 PM

THe newer Rotax 700 twins. The electrical would be the biggest challenge.