Quick front fork question ('02 CR250)

[mox69]

I took the front forks off my CR250 apart for the first time last night. It was actually a lot easier and less scary than I was assuming.


First, I didn't exactly have the 55mm wrench to pull the damper out. But oil did come out of the 2-3 holes near the top of the damper area.

Is the oil thats inside the damper totally sealed off from the rest of the system? Do I need to pour oil directly down those holes, or by pouring the correct amount of oil into the tube will I be ok?


I can make adjustments to oil levels by using a "fork oil level tool" , correct? (basically a syringe with a long small straw and a metal stopper to hold it at the same spot.)


One of the fork springs was actually broken about 2inches from the bottom. How on earth does that happen? Could using an electric impact wrench to take the forks apart cause that?


Lastly how do I translate a volume (say 375 ml) into something I can use with my fork oil tool? The fork oil tool has marks on the very bottom of the straw, starting at 10 and going up to about 275, what are these marks?



These questions should probably have been asked before I opened the forks, but I learn by experience :)

 

[bll]

no reason to pour oil into the holes

oil does make its way past the piston into the top of the internal chamber and out those holes into the main chamber

you don't need your fork oil tool anymore unless you want to suck some oil out.

get a ratio right and measure 375ml of oil and just dump it into the outer chamber.

 

[_JOE_]

Those marks should be millimeters, as in oil height. Set it to your desired level, say 1oomm, then suck any excess oil out. The manual will tell you the correct oil height.

 

[bll]

i dont think the honda manual does it in height, just volume

 

[IndyMX]

Take a look at the MX tech site, you should be able to find out the level in mm on there. It's probably going to be between 90 and 100 mm

 

[James]

Take a look at the MX tech site, you should be able to find out the level in mm on there. It's probably going to be between 90 and 100 mm

02 Honda's dont work that way. As stated earlier, you have to measure volume and add that amount to an empty fork.

You cant make adjustments with the fork level tool mentioned.

 

[IndyMX]

Errr.. 02 CR250 has the exact same forks as the 2000 CR125, so I assume if you can measure oil in mine in mm, you should be able to measure it in the CR250 that way also.

Doesn't really matter right now, mx-tech.com is down right now.

 

[mox69]

Yea I noticed in the service manual it says, do not use the height measurement, just pour a specific ml in there.


I went riding today and one of the tubes immediately started leaking. So either I put it back together wrong or there is a dent in the tube. If I remember correctly it is the same one that was leaking before. I cleaned the tubes off very well, so I guess I will inspect very closely for nicks.

I'm going to buy the correct springs for my weight and redo em all over again :)


Considering I tore the bike completely apart, I should be happy the only thing wrong is a leaky fork. Pretty nerve wracking flying 30-50 ft. through the air wondering if you tightened all of the bolts :)

 

[IndyMX]

Hmmm.. I saw a guy at the track one day that had just had his forks done by a guy who supposedly was a regular suspension guy. Well, his forks made an incredible knock noise when he got off the ground.. Like they were slamming down.

After some investigation, we discovered that one of the oil seals was in upside down.

They don't really work very well when they're in wrong. Check that.. Also check to see if there is any dirt in the seal.

 

[mox69]

Hmm ya I'm going to take them apart again in a week or two when I get the correct springs for my weight.

I had the factory service manual on the bench while I was doing this (granted it was about 11pm and I was in a hurry). I remember spending 5 minutes flipping pages in the manual to find the correct way to put the seal in. But knowing how I operate I probably still put it in backwards.


Also this was a brand new seal. I put new busings and o-rings in as well. I also made sure to put masking tape on the fork (like the manual said) before sliding it on. Maybe I still damaged the seal somehow.


On a related note, can anyone recommend a good book for MX suspension? Does and of Eric Gorr's books touch on the subject?

 

[IndyMX]

I don't know of a good suspension book, but mx-tech.com has some excellent articles. If the site comes back that is...

if you put the seal in with the flat part out, and the spring side in, they are correct.

I'd pry out the dust seal and see if you can see the spring.

 

[bll]

eric's books do touch on suspension.

 

[James]

Errr.. 02 CR250 has the exact same forks as the 2000 CR125, so I assume if you can measure oil in mine in mm, you should be able to measure it in the CR250 that way also.

Doesn't really matter right now, mx-tech.com is down right now.

Err...no they dont. You can't use a suction fork oil tool to set oil level in a 2002 CR250 and You can't rationalize it to be so.

 

[IndyMX]

Err...no they dont. You can't use a suction fork oil tool to set oil level in a 2002 CR250 and You can't rationalize it to be so.

Ok, why can't you?

 

[James]

Because the outer chamber oil sits down in the tube far out of reach of typical oil level tools. Also, the spring fills the diameter of the tube and even if you had a tool that would reach that deep...it wouldn't fit between the spring and tube.

If you ever had one apart (a set of SHOWA suspension from an 02 CR250 or similiar), it would be painfully obvious why it wont work.

 

[IndyMX]

Because the outer chamber oil sits down in the tube far out of reach of typical oil level tools. Also, the spring fills the diameter of the tube and even if you had a tool that would reach that deep...it wouldn't fit between the spring and tube.

If you ever had one apart (a set of SHOWA suspension from an 02 CR250 or similiar), it would be painfully obvious why it wont work.

Errr.. Well, I had read somewhere that they used basically the same KYB forks on most of their models.. I stand corrected.