V-8 from a Suzuki? V-8 from a twin Ducati? v-12 from a Kawasaki 6cyl.? v-12 from a Honda CBX ?? Check out the Kneeslider..it's all been done and more WOW.. http://thekneeslider.com/
For what it's worth some outboards, in the 60's and 70's, had electric shift gearcases (essentially a differential) in which the standard 80w90 was too heavy for the shift solenoids and the hydraulic mechanism they controlled. The outboard manufacturers came up with a Type C oil for those...
I believe it was Tyrell in the very early 70's that built a formula-1 race car with four wheels up front. Their objective was the use of much smaller diameter tire to reduce the frontal area and improve aerodynamics. It also, as noted, gave it better front end grip. They raced it a few times and...
Most bikes already have tachs. If not, an easy way (assuming the wire is more accessible) is to tap off the alternator before it gets to the rectifier and read the pulses off of it. Virtually all 2-stroke outboard motors use this method for the tach. Generic outboard tachs are readily available...