Motorcycle Forum

Motorcycle Forum (https://www.motorcycle.com/forum/)
-   Motorcycle General Discussion (https://www.motorcycle.com/forum/motorcycle-general-discussion/)
-   -   2012 Yamaha Super Tenere Review (https://www.motorcycle.com/forum/motorcycle-general-discussion/16967-2012-yamaha-super-tenere-review.html)

Doktor 11-09-2010 12:27 PM

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 11-12-2010 10:55 PM

Quote:

Originally Posted by Doktor (Post 251867)
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!


All times are GMT -7. The time now is 12:52 PM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2021, vBulletin Solutions, Inc.