Toe wrote: ↑Tue Feb 07, 2023 11:13 amI think it's to replicate a 90 degree because the firing order on a 270 matches the 90. Always thought it was properly kicked off by Yamaha with the TRX850 wanting it to mimic a Ducati!garyboy wrote: ↑Tue Feb 07, 2023 3:59 am Apparently, the 270 parallel twin was chosen to emulate the sound and vibration qualities of a harley? Bikers were complaining that the Japanese in-line 4 was Too smooth and quiet, and therefore bland.
People like Honda must have experimented with the offset setup and timing for ages, to get the right sort of vibration that resonated with bikers' bums lol.
My NC750 is such a 270 twin, and honda have certainly got the depth of exhaust note and inner rumble just right. Strangely, they say they left in the over-rumble when the engine is labouring, with some sort of plausible explanation, but I think it is more to do with overall compromise between fuel efficiency, sound, vibrations, and power.
IIRC the 270 crank was developed initially for the Yamaha works Dakar twin to give a 'rougher' power output, making them more like a single and better able to find traction...it then found its way into the road range via the TRX850.
Gray from SWTRF had a Super Tenere special, which IIRC, had an 850cc 270 degree engine, plus uprated motocross suspension.