Just want to take a few minutes and try to discourage everyone from modifiying the HS or Honda motors. Both motors will self destruct if run above redline [7800 RPMs] for any extended period of time. Both motors will explode [rod will leave crankshaft] because they are tuned in such a way as to “not know when to quit”. Several companies found this out when they offered kits with ratios above 20 to 1 and of course many owners tried to reach 35 MPH and found the motor turning over 9,000 RPMs [can you say "BOOM"].
Most motors are modified to add additional RPM and move the torque curve to a higher level, sadly the HS and Honda motors don’t work long at elevated RPMs. As an example, most Whizzer motors max at about 6,000 RPMs, however my record setting motors will exceed 8,000 RPMs and survive.
Best to increase HP and torque rather than increase RPMS levels. Becuase of the motor design, it is difficult to bore, increase compression, increase valve size, or increase the compression ratio [head is part of block].
If you want additonal performance from the HS or Honda motor, look into tuned exhaust systems, or better power transfer from the motor to the rear wheel. Both of these concepts will add addition HP and use the torque more wisely. Always remember a lot of power can be wasted in the drive system [gears, chains, grease, bearings, design, etc].
Here is a perfect example of advanced power transfer……….We recently upgraded the Q-Matic with a special balanced secondary drive pulley and EVERYONE reports increased low end torque, increased hill climbing ability, more top end, and a much smoother system. The change was from the original aluminum 5″ pulley to a steel balanced 4.95″ pulley. If the motor flywheel weight is increased [weed eater clutch on a tapered shaft] the motor will rev much slower, use direct power to spin the clutch at motor speed and transfer less power to the rear wheel. The Q-Matic doesn’t have the clutch on the flywheel and only spins the rear monted clutch at approx 1/3 motor speed, which uses far less power. The Q-Matic stores secondary “flywheel” action without taxing the motor as much as other systems.
It is possible to reach almost 50 MPH with the HS 142 motor, Q-Matic drive, 24″ wheels, tuned exhaust, 165 pound rider, light bicycle, no wind. The bike will easily average 40 MPH which is too fast for an average bicycle, illegal in most states, and strongly discouraged by EZM!
Quenton “Lee” Guenther