Yeah Steve the skinny crankcase is why I gave up on using a modern I.C. V-twin engine to power a vintage board track style bike, they're all four to five times too wide in the basic crank case width and they aren't round in profile. There are some Briggs, Kohler etc. tribute build s that are great looking moto cycles, but put them side by side with frames running the real deal motors and there's a huge visual dis-connect.
Fin diameter is just proportional to the rest of the motor. Fin's to the base not a problem, nor was tapering fin diameter from head to base plate. High exhaust port or low. V angles varied as did single cylinder verticality. Intake front, back or side location on singles. Early engines varied greatly and innovation was the order of the day. So in a non-specific tribute build one can just let their imagination and creativity fly.
Pipe or tube sizes can be used, diameter not super obvious to most observers standing, but kneeling or from 15' away standing; it's noticeable. Thicker fin material and closer spacing would help. I would notice 2" & just think small displacement motor, again not a big deal. I used 3" diameter drive shaft cut offs that's thin wall, light and much stronger than was required and I had it. There's a lot of scrape .tube out there wherever there is, and fin plates can be cut to suit whatever diameter tube is used. Pipe sizes are pretty heavy compared to tube but plumbing material could be employed as could exhaust pipe. It's all strong enough, but some are easier to weld with basic home welders.
I stitched the fins in place, to avoid warp and keep the pace up while building the cylinder fin stack. Weld clean up and repeat till finished. Three one inch run's per fin with 70,000 lb. wire. You can't make them ring with a ball peen!
Get to feeling better.
Rick C.
