Well the bore and all that technical bollocks I don't understand must be larger, but both air cooled and 2v so why not close? This has an oil cooler too, so no change. There are a few SS that are under 150 and need a little ballast, or twin brake not single. I ran single, it's saves loads of weight, but much less feel for the brakes IMHO. On the road tho, no prob
Well, I have dirt bikes and the engines can be a couple of kg difference due to thicker cranks and con rods and bigger flywheel weights,whilst the outside looks identical. I was asking on the assumption that a 620 might have been preferred for this project due to it possibly being a bit lighter.
A popular mod on the 900 motor is to use a 600 flywheel which is apparently significantly lighter, but more importantly the reduction in rotating mass makes a big difference (flywheels, cranks, rods, pistons etc )
