I'm building the engine of my 07 RKC in phases. Got the 103, pc III, jagg's oil cooler, and the wood cams. Getting a fat cat in the spring. For my next step, I'm looking into boring out the 103 to a 107 with some headwork and forged pistons at about 10.5 compression. I wonder about the capacity of the stock crank, clutch, and tranny. My goal is about 110 hp and (I hope) about 120 torque. I would like to stay with the wood 6-6 - been very happy with it. The question is "What's the limit of "dependibility" for the stock crank, tranny, and clutch? I love to get on it and go real fast, but I'm not into burning rubber from stop lights.

 

crank may or may not be an issue -- check the run out before the build, everything else will hold up well; probably need a SE spring for the clutch.

The other stuff I don't know about -- my HQs 103 was 105hp -- 117 tq I have not dyno'ed my 107 yet. HD transmission is solid.

 

The stock tranny has held up well to the 120" in my bike. SE spring may get you through for a while, but may give up and slip sooner or later.

Crank is a crap shoot. Lots of builds out there on stock cranks and they are not failing at a high rate, just some do fail though. Check your runout.

 

Sorta the same subject.
After a lot of figuring I used flatop pistons with my engine.
Time you bore the jugs to 3.937, I think it is, and use 0.030 gaskets, CP is getting up there.
The heads were also milled, 0.060 I just remembered.
Zero deck
I have 200 #'s cold cranking pressure, pleny enough.
And this cam is short also.