YZ426 Base Valve Stripped.. Any ideas?


33 replies to this topic
  • grayracer513

Posted March 11, 2012 - 04:54 PM

#21

The '06 YZ250F fork are the same as the 450 fork except for spring rate and some valving differences. The 450 springs are probably too light for the 400 anyway unless you are pretty light yourself.

The only difference is that the steering stem on the 250F is 12mm or so shorter. You should be able to press the stem down out of your clamps and press it into the 250F clamp to make it fit, but I'm not certain because of the age of your forks whether they share the same dimensions. Failing all else, Applied Racing and most other aftermarket triple clamp suppliers will sell you the stem as a separate part.

All KYB twin chamber forks come with plastic free pistons, not just the '05's. If yours are currently OK, there's a way to prevent them from breaking.

  • Schpenxel

Posted March 11, 2012 - 05:05 PM

#22

The '06 YZ250F fork are the same as the 450 fork except for spring rate and some valving differences. The 450 springs are probably too light for the 400 anyway unless you are pretty light yourself.

The only difference is that the steering stem on the 250F is 12mm or so shorter. You should be able to press the stem down out of your clamps and press it into the 250F clamp to make it fit, but I'm not certain because of the age of your forks whether they share the same dimensions. Failing all else, Applied Racing and most other aftermarket triple clamp suppliers will sell you the stem as a separate part.

All KYB twin chamber forks come with plastic free pistons, not just the '05's. If yours are currently OK, there's a way to prevent them from breaking.


Thanks for the follow up on the 250f fork info. With the price drop on the 2005 450f forks I decided to just go with those. They should still be a night and day difference over what I have now (well, I'm not even sure I know what I have now, so maybe I shouldn't say that yet) and reasonably priced. Now I just need to understand how to get all the air out of the inner chambers on these things (any mods to help with that?)

When reading earlier I noticed the recommendation to drill the hole in the plastic piston to help stop it from cracking, so I'll be doing that when I tear these down to change out fluid and inspect them.

A set of 05 triple clamps are 30-40 bucks on eBay so I'll pick up a set there. Question for you--will the bearings I have off my 2001 fit? They're all but brand new, so that'd be one less thing to buy.

And in regards to weight--I'm about 155lbs without gear, so I'm not sure if that classifies as light or not. Hopefully the springs will be close enough. This hobby is expensive enough already, and I barely get to ride compared to a lot of you guys!

Posted Image

  • grayracer513

Posted March 11, 2012 - 05:16 PM

#23

The tiny little hole they show there isn't going to help. Do this:

http://www.smartperf.../YZMODASSEM.htm

  • Schpenxel

Posted March 11, 2012 - 05:21 PM

#24

Sounds good--will do

Anything in particular to help with getting the air out of the inner chamber? I've read all the posts I can find on the subject--after I get them apart I'm sure it will make more sense where the air gets trapped.

  • grayracer513

Posted March 11, 2012 - 06:16 PM

#25

Did you read my writeup?

http://www.thumperta...ost__p__7613090

  • Schpenxel

Posted March 11, 2012 - 06:48 PM

#26

Yep. I'll just really need to have the parts in front of me before it all makes sense without pictures.

  • bonehead7101

Posted March 12, 2012 - 11:28 AM

#27

you can get bearings that will fit , as long as the stem isn't too fat. I live in sacramento,CA and there is a place called motion industries, if you call them and tell them the inside diameter of the neck and the outside diameter of the stem they can tell you what bearings fit. their website is www.motionindustries.com/ and the local number to the one here in sac is (916) 455-1990. these guys are awesome I use them all the time and usually they can ship directly to you.

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  • grayracer513

Posted March 12, 2012 - 01:27 PM

#28

you can get bearings that will fit , as long as the stem isn't too fat. I live in sacramento,CA and there is a place called motion industries, if you call them and tell them the inside diameter of the neck and the outside diameter of the stem they can tell you what bearings fit.


YZ/YZF steering head bearings are the same from '96 all the way to present, and the fork appears to be a '96 or '97, so that's simply not an issue. The only question here is whether the base of the stem that press fits to the lower clamp is the same.

  • Schpenxel

Posted March 12, 2012 - 04:30 PM

#29

YZ/YZF steering head bearings are the same from '96 all the way to present, and the fork appears to be a '96 or '97, so that's simply not an issue. The only question here is whether the base of the stem that press fits to the lower clamp is the same.


Question: Do I need anything beyond the triple clamps and forks (i.e. stuff like axle, spacers or brake caliper?) I'm hoping they kept it close enough that everything else will work as is, but I have read differing statements on which year triple clamps I can use. I ordered the 2005, thinking they would match up with the 05 forks, but have read I should have ordered the 06. Or maybe it doesn't matter, who knows.

Thoughts?

  • grayracer513

Posted March 12, 2012 - 09:00 PM

#30

You should perhaps have held out for '06 forks, but with '05 forks, the '05 clamp is the right choice. '04 clamps would fit the forks, too.

Nothing else would be needed if the bike had the original forks, but with those '96(?) forks on there, I can't say for sure whether you might need something else to go along with it.

  • Schpenxel

Posted March 13, 2012 - 04:37 AM

#31

You should perhaps have held out for '06 forks, but with '05 forks, the '05 clamp is the right choice. '04 clamps would fit the forks, too.

Probably, but considering how much I ride (not all that much) and what I'm used to with these 96'ish forks, these should still be a huge improvement and not cost all that much. I'm hoping Dave will email me back today with information on his products/fluid as well so I can get all of that stuff in & installed as well.

Nothing else would be needed if the bike had the original forks, but with those '96(?) forks on there, I can't say for sure whether you might need something else to go along with it.


Yeah guess I'll see. I still can't figure out why someone would switch back to '96 forks unless they had a very good reason. Or they were partially retarded.

  • grayracer513

Posted March 13, 2012 - 07:56 AM

#32

I still can't figure out why someone would switch back to '96 forks unless they had a very good reason. Or they were partially retarded.

  • They had money in the '01 forks and either sold them or kept them for their next bike
  • They trashed the original fork in a crash and got the old ones cheap so as to unload the bike


  • Schpenxel

Posted March 13, 2012 - 08:27 AM

#33

  • They had money in the '01 forks and either sold them or kept them for their next bike
  • They trashed the original fork in a crash and got the old ones cheap so as to unload the bike


Probably right. I am the 3rd owner that I know of for this bike.. the first owner apparently (supposedly) raced pretty seriously (so it makes sense he would have some money put into his forks) then the 2nd owner was an absolute idiot. Luckily he lived in the middle of a city and never really rode the bike, so he didn't screw too many things up.

  • Schpenxel

Posted March 15, 2012 - 03:54 PM

#34

And forks/triple clamps came in today.

Triple clamp went right on, original bearings/seals fit perfectly. I think the front number plate might be have to changed over to the new one, but no big deal.

Working with Dave @ Smart Performance to get his fork/shock treatment before I install everything.. Hopefully will have everything in time to finish it next weekend.





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