[Angel And The Wolf]

This idea has morphed so far from the two engines, two transmissions string, I thought it deserved it's own string:

Aerodynamic one person reverse trike.
One Motorcycle engine, with it's five speed transmission, Two output sprockets, each feeding one side of a Spur Gear Differential, with a dogged plate on the front sprocket of one side able to engage or disengage the front sprocket on that side, and a disc brake caliper on the rear sprocket of that side to hold that side shaft of the differential from turning when the front sprocket is disengaged. Differential feeds rear wheel by sprocket on the carrier case.

Speed in ratios would be:

Left/Right Feeds-------Final Ratio--Top Speed
1/1-----------------------13.990 --- 47 mph
2/2 ------------------------9.540 --- 69 mph
3/3 ------------------------7.450 --- 88 mph
1/Disengaged, braked ---6.995 --- 94 mph (Essentially halves the gear ratio)
4/4 ------------------------6.140 -- 107 mph
5/5 ------------------------5.260 -- 125 mph
2/Disengaged, braked ---4.770 -- 138 mph
3/Disengaged, braked ---3.725 -- 176 mph
4/Disengaged, braked ---3.070 -- 214 mph
5/Disengaged, braked ---2.630 -- 250 mph

I have not taken into consideration Differential Ratio, but that can be handled
by choosing proper larger front/smaller rear sprocket pairs.
Here, the ratios compared to just the five speeds:

Comparing CB750 + Differential to standard CB750 gears alone

2 in/1 out----Standard CB750
47 mph-------------47 mph
69 mph-------------69 mph
88 mph-------------88 mph
94 mph
107 mph-----------107 mph
125 mph-----------125 mph
138 mph
176 mph
214 mph (probably won't go this fast, but the gears are there.
250 mph