Development of the Commando engine

High level computer languages often work in radians rather than degrees. When porting a two stroke , port distances from TDC are important, so the conversion from crank degrees is helpful. I use the factor 57.296. Different motors often deliver power in different ways. The Commando 850 motor was a new experience for me. When it was accelerating - I suspected it was not pulling - I raised the gearing and the bike became faster. Raising the gearing had a very different effect when compared with my 63mm stroke 500cc Triumph motor. The Commando engine seems always to spin-up at the same rate regardless of the gearing. And it certainly performs better with close ratios. Raising the gearing with the Triumph motor caused slower acceleration out of corners, but higher speeds at the ends of the straights. A race change up one with the heavy crank and close ratios gives virtually nil loss of revs. I get a boost on every up-change, even with less throttle response.
No newly-built race bike ever seems to be good without adjustments. Some things which appear to be backward steps are often not. It took me too long to recognise the handling of the Seeley - it felt like a normal motorcycle.
 


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