Perhaps a 100cc direct drive with an Axle Clutch:
Power curve and engine sound reflects the power at the rear wheels.
Power at 10,000 rpm minus the loss due to the centrifugal clutch, until the clutch locks up and continues from there.
Main onboard Tacho shows real RPM, whilst the smaller arrow is speed, to help under braking as you no longer have the engind sound to go on. YMMV
Ignore any HUD Tachos.