Here it is Ken. Normal Vertical Twin motors have an even firing sequence of once every 360 degrees of crank rotation. Every time the crank goes around one cylinder fires and the next time it goes around the other cylinder fires. One cylinder fires at the 0 position for every 360 degrees rotation. If it was a clock, pistons fire alternately at the 12 oclock positionOne more explanation and I will be completely lost. Wait, I already am.
Now, what triumph did here is to stagger the firing sequence to fire at 270 degrees of crank rotation, which means that it will fire at the 0 position and then again at 270 degrees of crank rotation instead of going all the way to back to the 0 position after 360 degrees of crank rotation. If it was a clock one would fire at the 12 oclock position and the other would fire at around 10 oclock.