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[Bob B]

Here goes - some if not all of the Honda road going twins dud not use the conventional twin crankshaft design where both conrod/piston assemblies go up and down together, i.e. the engine fires once for every 360° crankshaft rotation. They used a design where when one piston was at TDC the other was at BDC. Thus the engine fired once at TDC and then the other cylinder fired 540° later. The thinking was that such an arrangement reduces the natural vibrations inherent in a 'conventional ' parallel twin motor, it also made for the distinctive exhaust note in bikes such as the Honda 305cc CB77.

I believe that Alan built such a crankshaft in the latter '60s which, whilst probably reducing vibration, did little in the quest for more power from a readily available engine.

HTH - if anyone knows differently then please speak up

[666]

i think Bob might be talking 180deg, Alan always used 360deg.we are now using 180 and 90deg cranks,some call them 270deg Alans bike made the wrong noise for a 180 or a 90,he used 360 with a 2 into one exhaust, it howled. the noise from a180 or 90 is a much flatter and gruff sort of noise.the only person that i remember using a 180 in the 60's was Mick Rouell with an Norton Atlas engine,i remember him well as he had one leg which he had to stick out backwards also i beleive that Geoff Monty of Monty & Ward Made a 67deg cranked Triumph for their own use.Bob you are of course correct it was done mainly to help the vibration problens on 360deg cranks

[Bob B]

Well, if it wasn't Alan then someone did, remember it clearly because the exhaust sounf stuck out from the pack like a sore thumb

[666]

The NSU is possibly Bob Pyetts