Paul..
Great questions...
Every rider rides different and subjects their sled to different stress levels.. I have my "group" that I ride with and only a few of us pull the big chute.. So, mountain riding is not all equal in these terms..
The dyno "hour tests" durability tests that the manufacturer's use is great testing but does not factor in ALL the parameters that are at play in a realworld situation. Take the 07 800R for instance, why was the case tolerances not caught in the durability testing? 08 testing.. why were the bad rods not caught? But back to the other players.. the durability testing has not tracks spinning, elevation changes, temp and density changes (maybe they can simulate this to an extent).. and just overall twisting and vibration of the engine and chassis.. there is simply not an easy method for simulating this sort of thing.
As for the new piston.. simple.. the #1 cooling agent at work in ANY 2 stroke engine IS the incoming fuel charge entering the lower end. The ETEC has eliminated this agent.. this WILL cause premature engine failure and accelerate component wear..
There is a reason why the 800R (2007) ran at 8500 rpms (stock) and the 2008-2010 800R at 8150 .. Now, the ETEC runs , initially, at 8000 rpms and now 7900 rpms. WHY? because lower rpms WILL always LOWER crank bearing, rod and rod bearing stress levels. This all relates to the ABSENCE of cool fuel entering the crank. So, lower rpms and this will alleviate SOME of the stresses at play in the crank.
The piston will keep getting hotter and hotter every revolution . this hot piston heats the lower end components every time it passes there.. So, the hotter piston (single ring vs. dual) contributes to the stress and heat on the crank.
Simple math and engine building formulas.. you can not EVER make more HP at a lower rpm on the same engine UNLESS the torque has been increased.. Maybe they have increased the torque at 7900rpm from the previous year engine..but I suspect they have not.
Kelsey
