'06 Fork seal problems

I'm having a very difficult time with seals on my 06 YZ450. I've had them changed by MX Tech and two other experienced wrenches. We've tried OEM and MSR seals. Forks have always been inspected and either dressed up or were OK. The longest they've lasted has been 7 rides. Usually one side will leak a little but my latest outing (mud ride) both sides leaked and one bad enough to cover the caliper. I'm 230 lbs and tend to land hard and wonder if that's the problem. Any advise would be great. I'll start with the film trick as I do see lots of dirt under the dust seals.

Your trouble is the dirt under the dust seals. You cannot allow mud to dry onto the fork tubes. Yamaha recommends cleaning under the dust seals each ride day. Applying a bead of grease between the dust seal and oil seal helps arrest the dirt before it gets under the seals, too.

If you ride mud a lot, consider using MSR seals and dust seals in place of the OEM stuff.

I have not had a seal go bad on me yet...when they leak it is from dirt that gets caught under the seal. I clean them out with a piece of 35mm film when I see any leakage and they are good to go.

Forkseals are the most common issue on 06s and up

either learn to clean under the dustshields every ride with oem or get a better design seal. I like the synergy seal product. :thumbsup:

I'll give both suggestions a try. Thanks-

Funny you should bring this up. I was down a the local Yamaha shop yesterday and they were talking about a guy who bought a 2006 YZ250 and one particular side kept leaking. So they mic'd the fork tubes, and one was smaller than the other.

Factory defect, Yamaha warrantied it.

Your trouble is the dirt under the dust seals. You cannot allow mud to dry onto the fork tubes. Yamaha recommends cleaning under the dust seals each ride day. Applying a bead of grease between the dust seal and oil seal helps arrest the dirt before it gets under the seals, too.

If you ride mud a lot, consider using MSR seals and dust seals in place of the OEM stuff.

gray, I bought the MSR seals because I heard you and a few others recommend them. Well, after 2 rides they leak and I have cleaned them numerous times, but they still leak. What gives? Oh and I rode indoors, no dust at all and not muddy.

Defective? Maybe, but I won't buy those ever again.

... the MSR seals ... (leak) after 2 rides ... What gives?
No idea. My son rode more or less indifferently on a set of them for 16 months. I told him top clean them. Sometimes he did. The other two sets are over a year old w/o problems.

My real favorite was the old '04 seal, but you can't get it anymore. Synergy's may be the last best choice.

Silicone spray lubricant...I have an '07 with 80 hours and no seal problems. Don't use high pressure for washing. Spray a folded paper towel to transfer lubricant to dry and clean chrome surfaces. Do same to monoshock rod. Mechanical seals benefit from silicone, too. High on that list is the steering head. Reduces sliding friction and eliminates seal sticking. I do it weekly during the riding season.

Funny you should bring this up. I was down a the local Yamaha shop yesterday and they were talking about a guy who bought a 2006 YZ250 and one particular side kept leaking. So they mic'd the fork tubes, and one was smaller than the other.

Factory defect, Yamaha warrantied it.

you may have stumbled on the real issue here - I am getting a micrometer out....:thumbsup:

I can just about promise you that one side will be smaller than the other. It's only a problem if it's smaller than it should be.

Out of round would be an even bigger issue, but it seems much less likely.

Tried SealSavers? $20 is way cheaper than rebuilding them multiple times.

I second the comment on seal savers. I run them all the way to the bottom of the tube. I have been doing this 4 years on 3 differnet bikes about 8000 miles offroad. You worry about where does all the material go when bottoming but it does squish out of the way. I found this out trying to get my seals to last in the winter. The temperature is below freesing but the streams are water. The water and dirt spashes on the fork leg and the freezes. When you bottom this fozen gritty layer would ruin the seal in a single ride. The solution was seal savers run to the bottom. This has also increased the service intervals on oil changes.

I can just about promise you that one side will be smaller than the other. It's only a problem if it's smaller than it should be.

Grey why would one tube size be different than the other side? Seems to me they should be identical. What am I missing here?

How much difference would still be considered the same size? They are mass produced, moderate precision parts, probably manufactured to a tolerance of +/- .001" or thereabout. If that's true, you could theoretically have two fork legs measure .002" differently, and both be within tolerance.

How much difference would still be considered the same size? They are mass produced, moderate precision parts, probably manufactured to a tolerance of +/- .001" or thereabout. If that's true, you could theoretically have two fork legs measure .002" differently, and both be within tolerance.

what would be a out of tolerance amount?

>.002?

mine are exactly the same diameter.....:thumbsup:

Using a vernier micrometer?

When a tolerance is given as in the +/- .001 example I used, and the size is specified as 1.89", that would mean that a tube measuring 1.891, or 1.889 would be within tolerances. I do not, BTW, know what the tolerance is for the fork tube, as the manual doesn't give it, and I don't put it beyond the capabilities of the Japanese to be able to hold a half thousandth (.0005") tolerance, even at this level of production. I'm simply saying that doing the kind of extremely high precision work necessary to hold tighter than that is not something you're likely to find on motorcycle suspension. If I'm wrong about that, I'm impressed.

Using a vernier micrometer?

When a tolerance is given as in the +/- .001 example I used, and the size is specified as 1.89", that would mean that a tube measuring 1.891, or 1.889 would be within tolerances. I do not, BTW, know what the tolerance is for the fork tube, as the manual doesn't give it, and I don't put it beyond the capabilities of the Japanese to be able to hold a half thousandth (.0005") tolerance, even at this level of production. I'm simply saying that doing the kind of extremely high precision work necessary to hold tighter than that is not something you're likely to find on motorcycle suspension. If I'm wrong about that, I'm impressed.

not sure on the type of micrometer

but my measurement .889 was consistant with both tubes.

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