Cdekmg@... wrote:
> I read discussions in the archives about this, and it would seem that
> looser is better than tighter. Sorry, I had archive search burnout and hope
> this question isn't beating a dead dog too badly.
We have a remarkable capacity to resurrect dead horses with plenty of
volunteers to flog them.
> With heavier riders, 2-up, luggage, etc., the manuals spec of slack seems
> too tight. I'm light, and with luggage and my weight, there is not much slack
> left, far less then the 5-6 inches of suspension travel left over.
If you were really keen on getting the slack spot-on, you could minimise
the shock preload and weight the bike so that the output shaft, swingarm
pivot and axle centres all lined up, then adjusted the chain tension so
it was snug (but not tight) at this point.
In theory, the factory already did this and that is how they came up
the unladen-on-sidestand figure.
All this assumes a new chain and sprockets. A worn chain with its
own tight spot will throw measurements out a bit.
> So, from what I read/per the manual it would seem that excessive
> chain/sprocket wear could result from inadequate slack.
Yes, and true on the vast majority of chain drive bikes. This excludes
some older Bimota designs where the swingarm pivot was coaxial with
the output shaft for the very purpose of eliminating chain tension
variation.
> My main question is: could a tight chain result in damage to the
> countersprocket shaft bearings?
Yes. It won't do the swingarm pivots any good either.
> Has anybody ever had these bearings fail or
> need replacing? Why did it happen, do you think it was the result of not
> enough chain slack?
Not me yet.
> It would seem that for the average rider with the chain adjusted to spec,
> that if you go 2-up with luggage (or even less weight) that the chain is
> stretched tight all the time.
Shouldn't really happen, but you would end up with the chain somewhere
near it's tightest point in the rear axle arc of travel.
> What kind of problems have people had because of lack of slack? Or, are
> these bearings really, really tough? It would seem they would have to be to
> take all that force and torque.
The bearing is fairly tough, and as long as the engine is running it
is fairly well lubricated.
A friend of mine managed to wear out a bearing because he did a downhill
"race" with the engine off (this was on a GPz900 which uses a similar
output shaft bearing lube system).
Running the chain too tight can also do odd things to the frame
alignment at a certain point in the swingarm travel.
Mister_T
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