Like all of us that have the XT660`s , the cush drive rubbers wear is a pain.
I found an article some time ago on the XT660.com thread.

The chain drive sprocket takes a tremendous load from the power of the engine , which causes the rear wheel bearing to wear excessively , even wearing the Chain Drive Hub Housing ,
The bearing will become loose in the housing at a later stage,

I fitted a double row bearing as apposed th the std single *row bearing.
And with Polyurethane rubbers .I got 56 000km without changing the rubbers again.

You only have to machine the rear hub bearing housing 5mm deeper /
The Bearing I used is still the same dia. as the original.
And machine the inner spacer also 5mm shorter.
It still uses the Standard Yamaha Seal






The following bearings will all work, but only the first two have rubber seals on both sides:

FAG 62304-2RSR (2 seals)
4304-2RS (2 seals)
SKF 4304 ATN9 (open - no seals)
FAG 4304-B-TVH (open - no seals)

Their size is 20x52x21mm.


1.Polly Rubbers R800 posted in SA !
2.And R950 posted anywhere in the world , incl, postage
3. Euro`s *65 incl. postage

__________________

The big question everyone will want to know is...

Have you still got any polyurethane rubbers for sale?

__________________

I would immedately order them.
Another question. What size is the new bearing?

like said in:

http://www.xt660.com/showpost.php?p=169627&postcount=40

__________________
Riding the Mad Mule !! ... no more... went orange...

As far as I understand Hunday used a different sized bearing. He just shorted the space and did not mill a new one like you would need with your suggested size of the bearing.
Despite there are bearing with the correct inner diameter (20 mm) and the width of 20,6 mm, i.e. this one 305704-2RSR.
Would this be an option or is the wider diameter of 25 mm needed to fix this issue?

he used a double row ball race... The double rows hold the inner & outer races
more stable under side loads as the pull from the chain would apply...
In fact is a clever idea .... My sprocket carryer will be seeing a bit of lathe time very soon..
I all ready have rubbers I made from 95A urethane sheet... they are as tight as the day I put them in still....

__________________
Harley Davidson..
The easyest way to turn gasoline into noise with out the side efect of horse power...

Yes I do , Plenty.
Mail me your address and I will tell you what to add for the postage ?

__________________

You have mail.

__________________

You have mail .

Hi Hunday,
what size is the double row bearing? I only found one with 20x52x21.
If so, wouldn't I have to have mill 6 mm deeper and shorten the inner spacer 6 mm as well?

Regards
Marcus