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Schpenxel

YZ426 Base Valve Stripped.. Any ideas?

34 posts in this topic

So, decided I was going to tear down the forks on my 2001 YZ426F and am running into the base valve nut being stripped off. I can halfway beat a slightly smaller than it should use socket on there, but even that isn't holding well enough to break thing thing loose (how tight are these supposed to be anyways?). The head on the other fork's base valve looks fine, although I'm going to wait and use an impact wrench on this one so I don't screw up another one.

The stripped one already looked pretty rough before I tried to pull it off, and apparently my efforts didn't help things. Any ideas on a method to get this thing off? Or do I need forget rebuilding these things and start looking for a used set on eBay?

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The base valve in a YZ426 with the original forks in place is a 14mm Allen socket, not a standard external hex.

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Then something is going on with these forks then.. I noticed in the manual they had a picture of an allen socket, but thought the picture may just be old.

I'll take some pictures tonight--but it was definetly a 20 or 21mm socket that I used and fit on there just fine, there was no way to use an allen socket

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Here are some pictures from today. Finished tearing down the forks. Everything I've read/watched on YouTube makes sense now--They're a lot simpler after you have them taken apart

Base valve after removal. Is this stock?

iPhone%2520036.JPG

Before removal. This one wasn't stripped off at all, the other one was the issue

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Bushings. Is that black stuff at the top of the picture normal? How do these bushings look? I know theyre really loose so planning on replacing them regardless

iPhone%2520039.JPG

and a big one of the dog

iPhone%2520043.JPG

Edited by Schpenxel

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That's a really old fork, and doesn't belong on an '01. The black coating on the bushing is Teflon, and that one looks in good shape. They will be loose when they're out in the open like that, so you have to judge their condition and fit by how they feel with the two tubes assembled.

I would have named the dog Winston.

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That's a really old fork, and doesn't belong on an '01. The black coating on the bushing is Teflon, and that one looks in good shape. They will be loose when they're out in the open like that, so you have to judge their condition and fit by how they feel with the two tubes assembled.

I would have named the dog Winston.

How old is really old? I've looked on eBay to see what they looked like in '98 and they all have the Allen wrench fitting on the base valve so evidently older than that. I noticed someone had written "01 426" on both forks, but figures they had just been sent off for a rebuild at some point and the shop labelled them. Who knows.

And should I replace with original forks or leave them alone? They feel like crap as is and are the opposite of plush for sure, but I'm not sure if that's because they're older/wrong for this bike or because of just being setup wrong.

Also, we call the dog fatass for obvious reasons

Edited by Schpenxel

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I would look for a newer set. Even a '99 - '03 set would be an improvement. '04's are a little better, '05's way better, and '06-'07's are really really good. All of them will bolt right up if you get the clamps with them. WR450 forks would work, too, but you'd want to revalve them.

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I would look for a newer set. Even a '99 - '03 set would be an improvement. '04's are a little better, '05's way better, and '06-'07's are really really good. All of them will bolt right up if you get the clamps with them. WR450 forks would work, too, but you'd want to revalve them.

Gotcha--How can you tell they're an old set, btw? Just by that base valve or is there something else different that is obvious to you?

edit: Also, looks like there is a set from a 2005 on ebay right now, so I might try to grab those. The triple clamps are pretty cheap. Emailed the seller with an offer so we will see.

Edited by Schpenxel

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Gotcha--How can you tell they're an old set, btw? Just by that base valve ...?

Pretty much. I know it's an older design than was used on the '98 model, so...

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Pretty much. I know it's an older design than was used on the '98 model, so...

Wow, wonder where the heck this thing came from then.

Made an offer on a set of 05 forks and triple clamp set. So we'll see what happens.

Also, interested in the 215.VM2.K5 fluid--How much does that stuff cost? Their website is a disaster (noticed your signature)

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Also, interested in the 215.VM2.K5 fluid--How much does that stuff cost? Their website is a disaster (noticed your signature)

Dave's website is in a state right now. He built it himself with a Microsoft Office based web page editor called Front Page that's so old (in computer terms) that a lot of people have never heard of it. Being Microsoft, it had "special" elements that had to be supported by the hosting server, and most web hosts have given up supporting those extensions. That basically took out his home page. What's there now is a kind of place holder 'til he gets time to fix it. The Contacts page still works, but sometimes you have to put in " /contact " manually.

He has a newer formula for the oil that's working even better than the old stuff did. I just sold the last stock I had for $22 for an 18 oz bottle, or $97.85 for a gallon in either "weight".

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I've worked with front page quite a bit, so I am familiar with it--hopefully he will get it straightened out.

I probably should know this, but how much fluid is Required after rebuilding these forks?

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If you don't waste any, one bottle of SPI #3 for the inners, and one bottle of SPI #5 for the outers will do it.

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Question: what forks are on the 2006 yz250f?

Are they comparable to the 2006 450 forks? Same fork, different springs? Or what?

I've found a set of 2005 forks and triple for $180 shipped

And a set of 2006 250f forks for $228 shipped. Triple clamps are another $30-45 or so.

Also, on this base valve--I went through pictures on eBay back to the early 90's on every Yamaha I can find, and couldn't find one that didn't have an Allen head on the base valve. So I dunno what these things are.

Edited by Schpenxel

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And for anyone still reading, I got the guy with the 2005 forks down to $100 shipped. So I'm going with those.

Need to find a cheap triple clamp now.

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And for anyone still reading, I got the guy with the 2005 forks down to $100 shipped. So I'm going with those.

Need to find a cheap triple clamp now.

One problem with the 2005 dual chamber Kayabas is the plastic compression piston assembly. Very common to find it is broken in pieces 100.00-150.00 dollars per side so be prepared for that expense. if you modify the new pistons they will last forever

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One problem with the 2005 dual chamber Kayabas is the plastic compression piston assembly. Very common to find it is broken in pieces 100.00-150.00 dollars per side so be prepared for that expense. if you modify the new pistons they will last forever

Thanks for the heads up. Hopefully I can avoid that expense, but I guess we will see when they get here

Is there a way to tell if that's happened without tearing them apart?

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Thanks for the heads up. Hopefully I can avoid that expense, but I guess we will see when they get here

Is there a way to tell if that's happened without tearing them apart?

"Nope"

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