2012 Yamaha Super Tenere Review

[Doktor]

You guys hosed the math on the 270 degree crankshaft config. Either Cylinder #2 fires 270 degrees after Cyl #1 or 630 degrees later (270 + 360 or one crankshaft revolution)

With a 270 degree crank parallel twin, there's just isn't anyway to get piston #2 at TDC 180 degrees after piston #1, well, unless you have serious problems.

[Kevin_Duke]

Originally Posted by Doktor

You guys hosed the math on the 270 degree crankshaft config. Either Cylinder #2 fires 270 degrees after Cyl #1 or 630 degrees later (270 + 360 or one crankshaft revolution)

With a 270 degree crank parallel twin, there's just isn't anyway to get piston #2 at TDC 180 degrees after piston #1, well, unless you have serious problems.

Good eye, Dok! You win some sort of (figurative) prize!

I finally got confirmation from Yamaha about this. I misread their Powerpoint presentation, mistaking "firing order" for "firing intervals." Here is the revised text you'll see when my tech guys can get to it:

It uses a 270-degree crankpin offset, which has cylinder 2 firing 270 degrees after cylinder 1, then cylinder 1 firing again 450 degrees later. This uneven firing order is said to improve a tire’s grip on slippery surfaces and also has the side benefit of creating an exhaust note very similar to that of a V-Twin.

Thanks for the edit, and sorry about the slip-up!