Belt tension Spec 09

[Hoople]

Thorns, I have a theory. Tell me if you think it holds any water. The spec on my belt is 1/4" deflection while on the Jiffy stand. The spec for the belt when the frame is lifted in the air is 5/16" deflection. Jiffy stand spec is without rider and both specs are @ 10 PSI.

Well if the adjustment for belt tension is greater with the bike on the ground, it means to me that the rear wheel and fork are following an arc which makes the belt tighter the closer the frame is to the ground. Therefore if the tension is tight on the ground without a rider, the tension MUST be even greater with a rider,, and even greater than that when with a passenger.

Therefore,, I believe while just riding along solo,,, when the suspension is asked to "squat down" due to the road, the belt tension would be tight enough that it would have to support some of the downward compression weight.

I am seeing belt tension actually limiting some of the frames downward movement which is something you would never want to do.

What do you think?

 

[Thorns]

That could be the situation with a "B" engine that is bolted in, but again the g-force of the downward movement as you describe would be greater and would either wear internal parts (like the inner primary bearing), sprockets, break the belt, or flex the pivot shaft at the swing arm. An "A" engine that is rubber mounted might have more movement. I think most would do an alignment with the bike cold. If the belt is too tight, when the pulleys expand this could be pulling the engine rear to the right, and that's why we are seeing the inner primary bearing erroding, and a vibration that you are feeling with your butt. Either way, if the belt is adjusted to 1/4" deflection @ 10 psi, when the pulleys expand, excessive stress is on the components. With the newer belts, I haven't seen anyone wipe off the cogs on the belt, and also with the newer belts, I haven't seen any breaking them with a stock or stage 1 engine. Also, what I have noticed is the rear wheel has alot of drag when the belt is tight and the drive system is hot. That can't be good. The rear wheel spins a lot freer when you release some of the belt tension.

Thorns

 

[hoggy25]

You guys are absolutely right. I'm bad. I was thinking of headlight adjustment. It's a (sensored) getting old. Memory seems to go 1st after looks.

 

[Buster]

Thanks again everybody, I need to stop second guessing myself all the time when I find something after a repair and think I created it rather then it being there before I worked on it. I questioned the owner about the vibration I felt and he thought it was normal. Maybe its just me being picky.

 

[Retrop]

If you overtighten any drive belt, it will generally tell you before you go 100 feet. They will be hard to shift and the belt will sing like a banshee when you go up to speed. There are probably more belts out of speck than there are ones in speck because most people think the correct specs make the belt overly tight. It is kinda like the guy who won't buy a torque wrench because he always says, I can tell when it is right. They call that the "Armstrong method". Either way, those belts are pretty forgiving. They won't throw you off the bike if you get it off by a little bit.