needle bearings don't look like normal needle bearings???

I tore apart the rear suspension of my 98' yz400 and I have a few questions concerning the needle bearings on the assembly under the swingarm.

I am just doing annual maintenance and I noticed that these needle bearings aren't like what are on the swingarm or any other bike that I have worked on. It looks like the needles are normal, but between the neeldes is a rubbery/white substance that doesn't seem to be a grease of any kind. The needles don't seem to turn either, it looks as if this substance is a self lubing bushing that has just worn out?

Is this normal, or is it something that I can deal with? Should I scrape out the rubbery substance and grease it, or is this actually part of the bearing?

Anything I can do without replacing the bearings?

If I do need new bearings, any suggestions as to where I can get them?

Thank you very much,

Brian Bills

those bearings have a thin plastic cage that hold the needle bearings in place during manufactoring. you can remove the plastic and remove the needle bearings. if you don't remove the plastic cage, you'll never get enough grease in the bearing. clean the outer race and needle bearings. lube interior of cage with a quality grease, insert needle bearings. lightly grease inner bushing and install in bearing. it is ready to reassemble. if you need to replace any damaged bearings, pivot works make great kits for numerous applications. good luck :)

Thanks for the reply.

So if I remove the plastic cage, do the roller bearings still stay in place, or are they going to move all over the place?


Brian Bills

You will see that on most bikes. If guys were to take the time and pull them apart most people would be asking about that. All it is, is grease that got heated up with dirt and water mixed in. After awhile the grease will just turn hard. It's normal I do my swingarm every spring.

All it is, is grease that got heated up with dirt and water mixed in.

this is incorrect.

the material shipped by Yamaha in the swingarm bearings is called MPL, an acronym for Microporous Polymer Lubricant. you can read up about MPL and everything else related to greasing your swingarm (including disassembly pictures) in the 250F FAQ at the following link:

the other questions above related to the loose needles coming out and are answered in the FAQ page above, and also the following post -- scroll about 2/3 of the way down:

and also see this link:

and finally this link on grease:

jim aka the wrooster

'01 wr250f




Thanks, that is just what I needed. It looks as though I'm going to have some fun with some neeldes tonight.

Brian Bills

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