Finally some progress. I opened up the frame to fit the Mini Rotor so it can be installed after the engine is fitted to the bike. This allowed me to run without a fan. It rips super hard after being able to adjust the timing. Unfortunately the aggressive timing and high compression are too much without a fan and it gets super hot.
I still need to cut the taper on the rotor to push it deeper on the crank. I'd like to be able to install the motor into the frame with the rotor already installed.
In the mean time, I drew up and 3D printed a fan to work with the stock fan shroud.
Going to try a simple PLA press fit fan for now. If my prints dont stand up to the heat and RPMs, I'll try cutting one out of aluminum. You can probably spot my base spacer in there too. Looking to bump around 2-3mm to drop compression and get the exhaust timing around 185 degrees.