Compression Ratio of Current Yamaha 90 hp Two Stroke
Can anyone explain the engineering theory behind the fact that the current Yamaha 90 hp two stroke motor has a compression ratio of 5.76:1 in cylinder 1, a compression ratio of 5.67:1 in cylinder 2 and a compression ratio of 5.86:1 in cylinder 3. The 70 hp two stroke which is also a 3 cylinder engine has a compression ratio of 6.1:1 in all 3 cylinders.
Re: Compression Ratio of Current Yamaha 90 hp Two Stroke
The 90 hp set up is similar to that used in the old V-6 Special and the 2.6 liter 225 and Excell.
On those models, both the port heights and head cc's are different to balance the differences in exhaust passage lengths from top to bottom.