How to take off the cylinder valve?

I have a 01 YZ250F and I have been hurt with a broken arm so I have been taking apart my suspension to see how the shims and everything. And it is very fun.

But I can't get the cylinder vavle off. Do you guys use the dampener rod holder thing to take it off? I tried heating up outside of the thing that the cylinder valve is threaded in to and using pliers to take it off and it still won't come off. Oh yeah, the only reason I used pliers was because I have a set of forks that are messed up because the white plastic thing exploded in it.

So how do I take the stupid cylinder valve off??

Do you see where the cylinder has 4 peens (one every 90 degrees) on the outside skin around the top where the CV screws in? These need to be lightly drilled to remove the peening pressure and allow the CV to be unthreaded. I prefer an end mill because it has a flat end and won't puncture the cylinder wall like the point of a drill can.

I don't have a set apart at the moment to measure the wall thickness, but you need to be sure you don't drill through the wall. Go slowly with the drill and take a little bit off and then see if it will unscrew.

I have a CV holding tool and a rod I put through the holes in the bottom of the cylinder. I use a heat gun to heat around the CV to loosen the loctite. They're very snug with the peening and the loctite.

Hope it helps.

:thumbsup:

Do you see where the cylinder has 4 peens (one every 90 degrees) on the outside skin around the top where the CV screws in? These need to be lightly drilled to remove the peening pressure and allow the CV to be unthreaded. I prefer an end mill because it has a flat end and won't puncture the cylinder wall like the point of a drill can.

I don't have a set apart at the moment to measure the wall thickness, but you need to be sure you don't drill through the wall. Go slowly with the drill and take a little bit off and then see if it will unscrew.

I have a CV holding tool and a rod I put through the holes in the bottom of the cylinder. I use a heat gun to heat around the CV to loosen the loctite. They're very snug with the peening and the loctite.

Hope it helps.

:thumbsup:

Yep...what he said. You'll see in this photo that the peens are just slightly drilled. Take your time and be careful. And it will take some force to break them loose. If you have any problems let me know, since I assume you're in the area.

Cart.jpg

OK. I got the CV off but I have a couple of questions:

1.I read that the CV isn't good and to order one through Terry Hay.What is wrong with the stock CV? Also do you know how much a CV through Terry Hay is?

2.I also read that something is wrong with the stock midvalve. What is wrong with it?

3.Also I weigh 140 without gear and am "5"10" and am a top 3 beginner and can clear most jumps and lightly bottom with the stock springs(.44 and 4.7?) and a 140mm oil level on big jumps. But I couldn't corner worth crap with the stock springs the bike would stand up everywhere and I could never take the inside line.

I do have .41 and 4.4 springs and I just got a subtank system. I have ridden with the .41 and 4.4 springs and it cornered pretty good but the front was alittle soft because I ran a 140mm oil height. So I was thinking about running the maximum oil level height with the .41 and 4.4 springs and the subtanks. Does that setting sound about right for me?

4. Could someone give me a valving suggestion?

i run terry hays CV replacement,it was around $60(i think) i have his email somewhere (if you need it i'll look for it) just make sure to have him send fed ex or ups because it would have been faster for a frikkin' kangaroo to swim here with it compared to the aus air mail !! it stops the leakage that comes thru some sort of channels inside the stock seal head,it also eliminates the seal so there is less stiction(it just rides on the bushing) it definately helped(you must also run his BV stack) but i think there is still midvalve issues i need to address but nobody seems to be able to come up with a straight answer :thumbsup:

OK. I got the CV off but I have a couple of questions:

1.I read that the CV isn't good and to order one through Terry Hay.What is wrong with the stock CV? Also do you know how much a CV through Terry Hay is?

2.I also read that something is wrong with the stock midvalve. What is wrong with it?

3.Also I weigh 140 without gear and am "5"10" and am a top 3 beginner and can clear most jumps and lightly bottom with the stock springs(.44 and 4.7?) and a 140mm oil level on big jumps. But I couldn't corner worth crap with the stock springs the bike would stand up everywhere and I could never take the inside line.

I do have .41 and 4.4 springs and I just got a subtank system. I have ridden with the .41 and 4.4 springs and it cornered pretty good but the front was alittle soft because I ran a 140mm oil height. So I was thinking about running the maximum oil level height with the .41 and 4.4 springs and the subtanks. Does that setting sound about right for me?

4. Could someone give me a valving suggestion?

You're going to get night and day opinions on this one.

Terry Hay and Jeremy Wilkey are two highly respected individuals in their field... and they are worlds apart on this subject.

Terry believes in eliminating the CV while Jer will tell you that's a step backward.

RT will tell you to remove the MV and put in a checkplate and MX-Tech prefers to make the MV more active with almost no float.

So, pick your preferred philosophy and see what path it takes you down.

Sorry, there is no "one size fits all" answer for this one. :thumbsup:

:thumbsup:

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