This forum has been a wealth of info on the XT660 and I've learned such a lot in the past two years.
After my XT660Z cush rubbers started to wear a bit, I decided to replace them on 10 000 km already. But also put some inner tubing spacers for extra protection.
I read in this thread on cush rubber modification ( http://www.xt660.com/showthread.php?t=12422&page=8 ) that a great tip is to use silicone grease to fit the hub into the rubbers with the tubing spacers.
It went as planned and was very easy to do, making the "throttle jerking" non-existent. What a pleasure !
Then after a while I noticed the silicone got hot and seeped from the hub and sprayed the rim and tyre. Cleaned it off but after a hard ride, found the rim and wheel side, as well as just over the edge of the tyre on the running surface, silicone grease! Now that scares me if I lean hard on a corner and ride on the edge of the tyre covered with silicone!
So just be careful with the amount of silicone used when doing this trick.
I'll clean it out soon. One needs minimal silicone to make things slippery....

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2014 XT660Z - Barrett pipe, DNA stage1.5, Barkbuster hand guards and handlebars, Pivot pegs, Teknik suspension, Guard-it engine protector combo, B&B rear rack, Trax topbox.

That could have been nasty. ...that looks like a very slippery tyre! Steve

I use a bit of dish soap and water. Disappears in no time.

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http://www.onepistononeworld.com/
http://advrider.com/forums/showthread.php?t=988891 'South Dakota to South America'

I just cable tied it all together when I did mine then cut them off when the wheel was in.
Glad your all good mate could have been nasty

My experience.
After 27 000 km, dumpers are still happy. Some wears are there, but it is not problem yet. I am convinced that inner tube with silicone works.
Once yearly I am replacing pieces of rubber and apply silicone (because water is entering into hub over time and silicone is easily soluble).
Be carefully to not over lube (it happened to me, too).
However, good post from DirkZ and always be careful during the first ride, for any case.
Petre

Silicone grease is not soluble in water. It is a hydrophobic polymer and is waterproof.

The reason those of you are seeing your silicone grease disappear out of the cush drive (and spread all over the wheel tyre) is not water washout, or for that matter heat (silicone grease is good for 200C) but because of a side effect of its free-sliding linear polymers (which give it its excellent lubricating properties). These slippery low intermolecular interactions also result in silicone greases having very low surface tensions so they 'spread' a lot more readily than mineral-based greases. It is this 'spreading' property of silicone grease that makes it less than ideal when uncontained (by a seal) and exposed to centrifugal forces (like in your hub).

It's a funny compound silicone, unlike any others and because it's often labelled 'grease', we expect it to behave like the mineral ones we're more used to, but it doesn't!

If you're really interested in silicone then have a read of this scientific paper amusingly, but appropriately titled - 'Why Silicones Behave Funny'...

https://www.dowcorning.com/content/publishedlit/01-3078-01.pdf

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Nice one Pleiades.
Apparently, I have made mistake here.
I have cleaned my tires with water and I have made misinterpretation of the result.
Petre

I used silicon grease when putting the hub back together.

I only a tiny amount to get a surface shine on the cut up inner tube pieces.
I have no issue at all and no sign of it seeping out. In fact the little that I used I think has eventually got absorbed by the movement of the rubber pieces inside the hub

CRC or WD40 works for me...





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

Thanks for all the info.
To add to the discussion I just have to confess that the initial seepage of silicone out of the hub was definitely due to too much silicon grease applied.
I wiped the silicon spray off twice after hard rides and it has now stopped leaking out of the hub.
So moral of the story: use it sparingly !

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2014 XT660Z - Barrett pipe, DNA stage1.5, Barkbuster hand guards and handlebars, Pivot pegs, Teknik suspension, Guard-it engine protector combo, B&B rear rack, Trax topbox.