Made a lot of headway on this build in the last few weeks. I was hung up for a while on how I should modify my crank, tranfers, and ports.
The pinasco 43mm small case half has a much different shape than the OEM small case half. There is actually a lot more meat on the outside of the OEM half, meaning you can open up the tranfers a lot better. The pinasco one not so much. I'm not a huge fan of using high heat epoxy or JB weld either.
Additionally I want the ability to swap kits on this bottom end until I settle on something. I have a polini and a biturbo kit to try on this bike after the malossi 43.
So, I ended up deciding not to touch the cases at all for now. Everything flows through the Swiss cheese piston on the malossi anyhow.
I did alter the intake timing, though, both by opening up the intake patch and cutting the crank. I made all my timing measurements after boring open the intake, but before cutting the crank. Here's what I got:
Intake Patch Opens @: 250 ATDC/110 BTDC
Intake Patch Closes @: 58 ATDC/302 BTDC
Intake Cycle Length: 168 degrees
Intake Patch Width: 39 degrees
Crank Web Width (stock): 125 degrees
Exhaust Duration: 162 (open/close @ 99)
Transfer Duration: 120 (open/close @ 120)
I wish I would have taken measurements before opening up the inlet. I would be curious if anyone has stock measurements? As you can see, though, opening the inlet alone makes for some pretty well improved intake timing numbers. I ended up wanting to aim for 185 degrees of intake timing vs the 168 that I had from doing just the inlet. And opted to
So I cut my crank ~8mm on the opening side and ~4.5mm on the closing side. This means the intake now opens at 130 degrees BTDC (which abides by Graham's suggestion of a 10 degree overlap between intake open and transfer close), and closes at 55 degrees ATDC.
Popped some bearings on and today this crank is going in the cases so I can start buttoning it up and getting the ignition installed.