looking for updated drive belt info XB12R

[motoqueiro]

Yep, that works too. The criteria and logic behind doing both holes is to leave the maximum amount of thickness at the remaining wall. I think by only doing one, and to get the proper amount of relief you're looking for, you have to get the ream closer to the perimeter edge(weaker)than if you do both. That's my $.02

It is funny that to achieve the same result, there are many different ways to do so.
My reasoning for doing it my way is that the lower slot rotates up and the force applied to the braket is down, so the thickness of the remaining wall isn't problematic..

[TheWood]

It is funny that to achieve the same result, there are many different ways to do so.
My reasoning for doing it my way is that the lower slot rotates up and the force applied to the braket is down, so the thickness of the remaining wall isn't problematic..

Not to split hairs here, but by pivoting on the top stud you'd actually be applying upward force at the lower stud, and thus, against the outside wall of the tensioner.

[motoqueiro]

Not to split hairs here, but by pivoting on the top stud you'd actually be applying upward force at the lower stud, and thus, against the outside wall of the tensioner.

You are, indeed, correct
It's thick enough
20231112_170714.jpg

[TheWood]

You are, indeed, correct
It's thick enough
20231112_170714.jpg

Seeing this pic., I agree(thick enough). Good job with your ream!

[motoqueiro]

Seeing this pic., I agree(thick enough). Good job with your ream!

thanks

[XB Richard]

well checking in . .
It turns out my tensioner already had 1 hole drilled over size, as per @thewood above.
So I elongated just this hole to 3mm from the edge.
Now the new belt is still over tight . . with i'm guessing 10 lbs pressure, there is 5-6mm total deflection.
All my efforts seem to have released excess pressure on bearings etc,
but there is still no appreciable belt freeplay.
Now the idler wheel hits the original muffler . . which needs "relieving".
Fitting the belt, axle snug with no tensioner, hand pushing the tensioner up against the belt,
would leave the mounting stud 1/2 hole past the edge. Not counting muffler interference.
This belt is labelled "0500 1AAH". It looks thicker than the original . . i'll measure them.

[TheWood]

I'm thinking your belt tension is fine if you were able to get it on. It's suppose to be rather tight, and will loosen up(slightly)in time. Go easy for 100 miles or so(this is just my stab at a guess). For the record(and as I laid out in post #15), It is recommended to ream both holes. Leaving only 3mm's of bracket material at the edge is just too thin IMO. If you're that close, and in addition to now touching the muffler, I'd guess that your flange nut when installed is hanging over the edge a bit. I tend to be a bit anal about these things(Dad was an engineer)and couldn't live with that. Symmetry is best in this application.
You have a few options. 1.)Dimple your muffler to accomodate, and go ride 2.)Find another tensioner bracket and start over doing both the holes 3.)Shim up the oversize hole and ream the other one until you get the right fit.

Edit: I just looked at the space between my pulley wheel and my stock muffler. I don't know how your frame varies from mine(if any)but the space where it is the closest on mine measures 3 mm's, and it is right at the rear muffler strap. Are you saying that yours is touching on the strap there? If so, a "dimple" as I previously mentioned would be a bit more problematic. I see that as the pulley wheel drops down, it would get closer and closer to that strap. Good luck, let us know how you work it out.

[XB Richard]

well as you say the pulley rubs the muffler.
3 times while enlarging the mounting hole I wacked the muffler with a chisel . .
Now the pulley securing bolt hits the muffler strap, and the belt is still way too tight. getting nowhere.

2 days later . .
A friend came over.
With no pulley fitted the belt is loose, but not touching the swing arm.
2 of us leaned on the rear and the belt tightens up as the suspension compresses . . real snug.
Ok I rode around the block . . the belt is hitting the engine casing/ pulley mount.
There is a mark on the outside of the belt where it rubbed. . it didn't do it on the stand. groan.
. . where am I . . getting nowhere .

2 more days later.
I can now see how Mr Buell designed the belt drive.
The idler pulley controls the belt slack when the suspension is unloaded.
When the rear is loaded there is almost a straight line between the bottom
of the front pulley and the bottom of the rear drive pulley. The idler does nothing
and the belt length apparently perfectly matches the distance between the drive pulleys.
So thinking thinking . .
I can't alter loaded suspension belt tension.
But I shouldn't need to because the original belt lasted 15 years right?
The unloaded belt tension is still too tight but I can't modify the tensioner anymore
without completely butchering it or designing a new one, so . . what about a smaller pulley??

2 more days later . .
My friend John found a Gates(38005) pulley on sale at a local auto store. ($5 bargain!)
It's 82mm x 30.5mm . Thats 20mm smaller od and needs spacers "fashioned" to fit.
John is making those for me too. . .
Will it all work?? I'll find out in a day or two.

John came over:
Fitted it all with no mods to tensioner mounting bracket. Just a few washers either side
of the new pulley to center it. So I can replace the original pulley if required.
Mods were required to the engine case around the lower idler mounting stud.
The inside edge of the belt passes over the casting, this is what rubbed in my earlier test ride.
About 2 - 3mm chamfer solves it. . delicately with a sanding disc on a grinder.
results so far:
After riding some kms, some of the belts stiffnes has gone giving a little more belt freeplay.
Next day went riding up my favourite mountain, about 110kms (70mls),
bike went really well. Feels a little more responsive off idle now there is some freeplay.
Total belt play has increased to about 25mm (1"). I can remove some of that now that the
idler mounting hole is bigger!
It feels good to ride with no snatching so that's where i'll leave it for now.
Later i"ll remove the cover (again! ) and take some pics and post them here for others to see.
Thx again to my friend John who saved my sanity helping with this project.
Cheers for now. Richard.

[TheWood]

As you say; "original belt lasted for 15 years right?"(0500 1AAH). What has changed? Well, it seems that you have rotated your tensioner too far(and pivoted on just the one hole), and is now hitting your muffler, unless something else changed and is askew. Your swingarm is shorter than mine and what I see is of course slightly different than yours. Hopefully others with your model that have done this mod. can chime in. You shouldn't have to be reinventing the wheel as you are, but I wish you luck in figuring it out.

[XB Richard]

pls see previous post for more info.
below is pic of new gates 82mm tensioner wheel.
notice the mounting stud position in its elongated hole.
in this position there is 20mm total belt deflection, (with 200kms only on new belt).
also here you can see the dent I had to do to the muffler outlet. No problem there now,
but the belt is too close to the bottom of the plastic cover. .
xb12r-tens3.jpg
..
..
below you can see clearance to muffler mount,
and shims to center new wheel in mounting fork.
note: original wheel and its shims are untouched . . in case . .
xb12r-tens2.jpg
..
..
not much room but more than before
xb12r-tens1.jpg
.