Crankshaft angle.

[Caito]

Hi guys, I've got a new question.

I realized the new Super-Teneré (Yamaha, 1200cc bike) has parallel twin cylinders. Nothing rare with this.. the thing is the cylinders aren't opposed but 270° appart.


With a firing order of 270°,450°.

Reviews say something to smooth torque, but no real good explanations. Anyone has one?

I've also heard they've been running this configuration since '96 on other bikes.

Bye bye!


Caito.-

[Caito]

No clues?

[mcjamweasel]

The Triumph Bonneville America, Speedmaster and Scrambler (865cc parallel twin) also have 270 degree cranks while the Bonneville, Thruxton and T100 run the same engine but with a 360 degree crank.

The 270 version is a torquier, lazier engine but with more vibration and less peak power than the 360. It feels closer to a V-twin than a parallel.

[hardingfv32]

Big bang system?

"The 2009 YamahaR1 has been officially unveiled by Yamaha, and as we predicted, it has a Yamaha M1-like big bang firing order. The first time a big bang engine has been used on a production bike, YamahaR1 is considered to be called, "Cross-plane Technology" and puts each connecting rod 90º from the next, meaning the cylinders fire at 270°- 180°- 90°- 180°. This spreads out the power pulses to the rear tire, allowing it to regain traction in between each pulse. The result is more usable traction under large throttle openings, meaning riders will be able to accelerate out of corner earlier and harder."

Brian

[flynfrog]

this explains it pretty well

[CMSMJ1]

@ OP post - it is all about getting the bike to sound like a V twin... nothing more, nothing less.

The motor that they used - TDM850, TRX850 and so on - could run a std 180 degree crank throw and sound flat like a parallel twin.

Or, they could put the bangs closer together and mimic a firing order of a V twin