The compression ratio of the engine was raised.

Along with other modifications to the engine, the compression ratio was raised to 10.5:1, and the V-Boost system was added.

The compression ratio was raised and the lower three gear ratios were mildly lowered.

The compression ratio of the engine was raised to generate more power, bringing it nearly on par with Kawasaki's powervalved Tecate-4.

At the same time there was a marginal increase in maximum torque, and the compression ratio was raised from 6.5:1 to 6.9:1.

The engine was bored out by 1/16 of an inch to take the engine capacity to 138 cubic inches and the compression ratio was raised.

The powertrain was modified too, compression ratio was raised from 6.2:1 to 6.8:1.

For this flight the compression ratio was raised to 7:1 to provide sufficient power for the heavily fuelled aircraft at take off.

The compression ratio was raised to 7.5 to 1.

The notable exception to this was the 1976 model year, where the compression ratio was raised to 9.1:1.