Increasing the compression ratio is one component of many that will increase a SUZUKI GS / EFE’s HP. An increase in an engine’s compression ratio will provide more power for less fuel and add some snap when the throttle is opened.
Raising the compression ratio gives the greatest benefits with initial increases. This means that more HP is produced by the first point increase of the compression ratio as compared to the next point of increasing the compression ratio. To illustrate this lets use a stock 1985 (USA model) GS1150 (EFE) as an example. The stock compression ratio is 9:7.1 if you increase the compression ratio to 10:7.1 there might be a 4 or 5 percent increase in HP. Further increasing the compression ratio to 11:7 might only provide a 2 or 2.5 percent increase.
The reason for the a smaller percentage in the increase in HP with a further increase in the compression ratio is due to the aspect of the GS / EFE cylinder being like an lung, increasing its volumetric effiecieny basically means the lung is filling with more air and is breathing out more through the exhaust. It is not enough to just increase intake or exhaust. Both must be made more efficient.
GS / EFE 1150 stock cams open and close the engine’s valves with little or no overlap. This prevents emissions from escaping, but it also limits an engine’s breathing efficiency.
In conclusion a moderate increase in compression will use less fuel to produce more power and the extra cylinder pressure and heat generated will increase the gasoline’s burning efficiency. But if you really want to maximize the advantage of increasing a engines compression ratio this use of a Hi-performance camshaft is required.