740 big bore for 670

Call the Crankshop at (802) 878-3615 they can tell you h.p. numbers.  I was looking in my catalog but it doesn't give h.p. numbers.  For tech. call after 1:30p.m. EST...

Just pulled mine yesterday. 142 HP.

I know of a couple of engine biulders in my area that tried the big bore 670 thing, with not much success, very small intake port seems to limit power.

HEY KRUSTY. IS THAT A SINGLE PIPE? WHO'S BIG BORE KIT? WHAT RPM? TELL ME MORE. THANKS IN ADVANCE.

Based on a 95 Mach 1. Twin factory pipes, 44mm carbs, and airbox. A local performance shop owner and  I designed it last winter. We used Wiesco sleeves and Rotax pistons from the 800 twin. Had to shim cylinders for crown hieght also. We used an H.O. head machined to work with the flat top pistons. A little more work, but I wanted to use cast pistons. Around 1200 miles on it so far with no problems. Lot's more power there but I didn't want to be playing with it a lot. There are kits out there that are less work but they use forged pistons. My kit cost me $2400.00 CDN, and I already had the head. It,s worth it though when I go by the new sleds on my old beater.



It turns 8100 rpm. Also made a billet RV cover to open intake up. Could easily see 150 HP with a little tweaking.