850 bottom end

Hi all and good Eastern.
Please, i have a 850 (not MKIII) bottom end i dont need.
What parts can i use for a 750 projects?
Sure the crank and conrod, cam, pushrods, lifters.
Sure the timing parts.
Sure not the crankcase valves and cylinder.
But can i use the head?
Thank you.
Piero

Hi Piero,

You can use the complete bottom end, but not the barrels or head. The 850 crank has a heavier flywheel which will be okay, but it might require rebalancing for the 750 pistons. The head will not fit on 750 barrels as the four outer bolt holes are spaced differently.

Martyn.

Why not just build up an 850 if you have all the parts you listed then it sounds like you have most of an 850 engine already.

Another option is to have the cylinders sleeved down to 73 mm, and then you can use all the parts.

I wouldn't worry about the effect of the heavier 850 flywheel. It will increase the balance factor with the 750 pistons, but that should not be a problem. The isolastics still work just fine with the higher balance factor.

Ken