Why do Yamaha apex turbos belts last so long?

[yamboosta]

THe 2 stroke machines clutches run super hot and string quickly. The yamaha ones last forever. Why??

 

[Rubberdown!]

Efficient R & D program?

 

[thinksnow]

Quality products setup correctly????

 

[Yammerhead]

I posted this a while back in the old forum on an XP clutching thread. It's my opinion as to why the big bore two strokes seem tough to clutch...

I read at one time (from someone who I would consider knowledgeable) that the Fusion 900 design incorporated a lightweight crankshaft. The combination of the lightweight crank, big bore torque pulses and twin cylinders resulted in a peaky, harmonic rich torque signature. The result was large torque spikes, poor belt life and lots of vibration.

Here's a link that explains it, albeit in 4 stroke terms. Torsional Excitation


Does anyone know if the 800R crankshaft is any lighter than the previous 800 Doo engine?

Since then I have found out that BRP has added a starter ring gear to the clutches on the 08 800R motors. I believe they weigh a couple of pounds and I am sure they added them to dampen some of the harmonics on the crank. The four stoke Yamaha torque signature is much different than the two smokers and I think performs much better with a CVT drive system. I think it is also the reason Yammie never made a big bore twin.

BTW, All the above is pure speculation from myself and I have no formal training in any of this. I'm just a dork who spends way to much time tinkering with sleds and not enough time riding.

 

[Linc]

One really important thing to realize about the Yamaha design,is that the clutch is NOT attached to the crank,the harmonics do not reach the clutch.The old quad 4 800 was the same,that thing would run forever on a belt.

 

[powdermuncher]

The Deltabox and super strong engine Mount system keeps the belt properly aligned no mater how much power you crank through, there is just no flex there -------Build like tractor ----------

 

[Rubberdown!]

LIKE I SAID,.......THE R&D department doesn't speak FRENCH! Got sushi?

 

[bmiller]

One really important thing to realize about the Yamaha design,is that the clutch is NOT attached to the crank,the harmonics do not reach the clutch.The old quad 4 800 was the same,that thing would run forever on a belt.

I believe that the only sled where the clutch is not attached to the crank is apex and rx-1 sleds.