FJR vs Tenere Middle Drive

[Constant Mesh]

Both the FJR and Tenere have gear drives powering the rear wheel. Yet the middle gear units on the output of the transmissions are very different.

The FJR has three separate parallel shafts -- the two transmission shafts and the middle gear shaft. The Tenere just has two -- the two transmission shafts.

https://www.yamahamotorsports.com/partviewer/default.aspx?ls=sport#/Yamaha/SUPER_TENERE_-_XTZ12DG_-_2013/MIDDLE_DRIVE_GEAR/XTZ12DG_(2013_MOTORCYCLE)/MIDDLE_DRIVE_GEAR_(XTZ12DG_-_2013)

The Tenere configuration is much simpler. Fewer shafts, fewer bearings, fewer gears, etc.

Design evolution, better design, less robust design, or just looking for ways to cut costs?

 

[kballowe]

Less robust design/cost. Tenere=less horsepower, less weight.

Just guessing.

 

[rPGoatBoy]

I think it also has to do with the frame geometry differences between both bikes, and the ground clearance differences. The frames and engines are usually designed in conjunction with each other. Both transmissions are "stacked" , but the Super Tenere can get away with having its output shaft mounted up higher in the engine casing (not requiring that third shaft to drop it down), as the swingarm travel on the ST is much greater than the FJR. The Feejer needs considerably less ground clearance, and there's benefit on a street bike in having the C of G lower on the bike.

Check out the cool animation on YouTube:

 

[Constant Mesh]

The Kawa Concours 1400 has just two gear shafts too -- the two transmission shafts. They use an interesting design where the transmission's output shaft is broken into two parts with a small bearing separating the two.

A very clever, compact design. Kawa often offers some nice engineering solutions. They must corral a lot of the country's best engineers.

 

[Checkswrecks]

I think it also has to do with the frame geometry differences between both bikes, and the ground clearance differences. The frames and engines are usually designed in conjunction with each other. Both transmissions are "stacked" , but the Super Tenere can get away with having its output shaft mounted up higher in the engine casing (not requiring that third shaft to drop it down), as the swingarm travel on the ST is much greater than the FJR. The Feejer needs considerably less ground clearance, and there's benefit on a street bike in having the C of G lower on the bike.
Check out the cool animation on YouTube:

 

[wfooshee]

The animation treated the transmission shafts as a single unit, rather than loose gear wheels. They need to do it again!!!

Otherwise, that was pretty cool.

 

[lnewlf]

Yup...and would that be a damper on the output shaft just before the bevel gears...and is the damper on the FJR similar?

 

[Constant Mesh]

The FJR has a similar spring-loaded dampener but it's located on the third shaft. It's interesting how the dampener cam is built into the bevel gear on the Tenere.

This animation shows a spark timing similar to a 90 degree V-twin. I thought I read somewhere that the Tenere operated like a big single with two sparks just 90 degrees apart and then a long 630 degree interval before the next pulse.

 

[escapefjrtist]

<snip> This animation shows a spark timing similar to a 90 degree V-twin.

Yup, sounds like a 90 V Twin as well.

From Yamaha:

The 1199cc parallel twin liquid-cooled engine features a unique 270° crank for superior traction because both pistons fire so closely together.

--G