02 KX 125 Forks - Whats up with the bladders?

Questions and comments about converting to beefier forks..
Post Reply
User avatar
Dewey
Supporting Member
Posts: 88
Joined: 12:50 pm Jul 31 2007
Country:
Location: South Central TN

02 KX 125 Forks - Whats up with the bladders?

Post by Dewey »

Ok Guys, ya talked me into doing the USD conversion. I bought a set of 02 KX125 forks in good shape. So now I start researching how to revalve for woods riding and I hear the mention of removing bladders from the 02 forks.
I guess I didn't research enough, what is the deal with the bladders, I haven't came across forks with bladders before. Are these OK to use in my conversion or should I find another set? Should I remove the bladders? What effect does removing them have?

I weight about 205, mostly ride tight technical trails, but like to take a few laps on my buddies practice MX track occasionally (no big jumps).

Any information is appreciated. What is the typical shim stack change or setup? I'm thinking the stock springs should be pretty close for my weight. I am considering Gold Valves, but would like some advice from someone that has been down this road before.

I'm so confused !:?

Thanks
Dewey
02 -KDX220
User avatar
scheckaet
KDXRider.net
KDXRider.net
Posts: 3740
Joined: 12:09 am Nov 10 2005
Country:
Location: edmond oklahoma

Post by scheckaet »

I converted to 01 KX, they had bladder, removed them and removed some of the shims to make it more wood friendly.
The bladder were for SX and big jumps if I recall.
Before going big $ on valve, try working with the shims you have, I believe you usually remove most of the big shims. I'm sure someone else will shime in for more tech answer.

Good luck
User avatar
Dewey
Supporting Member
Posts: 88
Joined: 12:50 pm Jul 31 2007
Country:
Location: South Central TN

Post by Dewey »

Does leaving the bladders in have an adverse effect for woods riding? Might be kinda nice for the unplanned big hits (like trees, rocks, 4' drop offs, etc.... Not that I've ever done that!) :oops:
Dewey
02 -KDX220
User avatar
bradf
Gold Member
Gold Member
Posts: 703
Joined: 02:17 am Dec 11 2004
Country: USA
Location: Anderson, SC

Post by bradf »

The bladder was an attempt to deal with bottoming. On fast SX/MX whoops and hard front wheel landings they would increase the mid stroke resistance and reduce mechanical bottoming. But as it turned out, the design was too harsh in the mid stroke for most. For woods and GNCC, it and it's hardware was commonly removed and some simple shim removal made a good balance. There are simpler but less effective ways to deal with the bladder like modify the BV circuit so much it actually relieves the pressure felt in the MV. I opted for the removal. I removed mine, modified the restrictive barrier (will go deeper into that in email if you want) and removed some BV shims. Very simple and well worth the effort. I even have pics, lots of pics.
'04 220 w/'01 KX250 USD forks, '02 RM125 Showa shock, Rekluse EXP 3.0, LHRB & all RB'd
User avatar
skipro3
Gold Member
Gold Member
Posts: 4329
Joined: 11:58 pm Nov 04 2004
Country:
Location: BANNED FOR LIFE!!
Contact:

Post by skipro3 »

When you removed the bladders, did you take them all the way out or just take th spring retainers that they seal by on the top/bottom off? If you took them all the way out, how did that affect the amount of oil each fork leg used?
Post the photos!! What is the restrictive barrier and how did you mod?

I have 2002 KX250 forks (Along with a 2002 KX250) and removed some base valve shims; 6 out of 10 of the big ones. How is that any different than what you did to your shim stack?
Jerry

I'd rather be a smartass like carvr, than a dumbass like.... well, you fill in the blank!
User avatar
scheckaet
KDXRider.net
KDXRider.net
Posts: 3740
Joined: 12:09 am Nov 10 2005
Country:
Location: edmond oklahoma

Post by scheckaet »

this is what I've done to my restrictive barrier

Image
User avatar
bradf
Gold Member
Gold Member
Posts: 703
Joined: 02:17 am Dec 11 2004
Country: USA
Location: Anderson, SC

Post by bradf »

I took everything that deals with the bladder out:
Bladder
spring retainers obviously
white plastic collar

then as scheckaet showed, you must make way for the oil to get back past the RB, which is no longer a RB but a good machined metal spring seat so the spring wont damage the actual seat.

If yours has a MV assy vs a check plate, there are two options there:
remove the bleeder shim to eliminate some mid stroke harshness, or leave it in if you will be doing hard whoops or front wheel landings (MX).

Taking the BV shims out and leaving 4-6 of the 24's is common amongst all. This allows the BV stack to be progressive and still allow the MV to pick up the action when the BV is overloaded. I left the bleeder shim in the MV

The boys at the local MX track took mine for a spin just to say they did a KDX on the track. It was funny to them. The instructor actually was shaking it down to see if it was balanced and track ready. 2 out of 5 absolutely loved it, 3 needed about 4 more clicks of compression front and rear then they liked it. But they were ani-mules on the whoops. Really fast and aggressive but very smooth on the landings.
'04 220 w/'01 KX250 USD forks, '02 RM125 Showa shock, Rekluse EXP 3.0, LHRB & all RB'd
IdahoCharley
Supporting Member II
Supporting Member II
Posts: 1005
Joined: 06:57 pm Mar 19 2005
Country:

Post by IdahoCharley »

>|<>QBB<
bradf wrote:I took everything that deals with the bladder out:
Bladder
spring retainers obviously
white plastic collar

then as scheckaet showed, you must make way for the oil to get back past the RB, which is no longer a RB but a good machined metal spring seat so the spring wont damage the actual seat.

If yours has a MV assy vs a check plate, there are two options there:
remove the bleeder shim to eliminate some mid stroke harshness, or leave it in if you will be doing hard whoops or front wheel landings (MX).

Taking the BV shims out and leaving 4-6 of the 24's is common amongst all. This allows the BV stack to be progressive and still allow the MV to pick up the action when the BV is overloaded. I left the bleeder shim in the MV
Couple of comments.

First I had 01 CR125 KYB forks with bladders that I modified for our KDX but they are essentially the same as the KX KYB forks.

Brad has some good information on the mods that will allow these forks to work well for woods.

However scheckset's method of reducing the barrier restriction is not "open" enough to allow the necessary volume of oil to flow. I had attempted something simialar (first with holes then with slots) and had to go back into the forks twice opening up the restrictor plate area to about 50% using a bench grinder and file. Looks like a daisy pedal in the end.

The bleed shim that brad mentioned in the midvalve should be left in the midvalve if you are going with a clamp set or reverse taper mid-valve. Leaving it in give free bleed through the initial part of the fork travel (a good thing for woods riding) Brad wrote it up a little ass backwards IMO because leaving it in will elminate some mid-stroke harshness IMO. Take it out for primarily MX or dune riding leave it in for woods or gncc type riding is IMHO .

If you really want the oil barrier restriction removed and the "forks plush" pop for Factory Connections spring seat. Check it out and you will see how it works in theory. I did not do it because it would also have required new springs for our CR forks and the forks are currently acceptable for woods riding.
KTM 380EXC Mine
KDX 200 Mark's
TTR 125 L Wife's
KDX 200 Austin's
EC 300 Tyson's
WR430 Husky - mine
User avatar
bradf
Gold Member
Gold Member
Posts: 703
Joined: 02:17 am Dec 11 2004
Country: USA
Location: Anderson, SC

Post by bradf »

IC is zacary right. I said it ass backwards. I knowed what I wanted to say but said it right for the other way. My RB mod was done with a bench grinder and come to think of it. it does look like a 5 petal daisey! I'm thinkin that the slots will work if there are twice as many. I always suggest leaving the bleeder in for woods. Even the Hare Scramble guy should leave it in even though they hit the MX track at times. It is the hard fast whoops and front wheel landings that really demand the removal to keep the travel from shooting through the first half of travel, leading to inevitable bottoming.

IC, you are like our grammar checker. A scrutinizer of the meaning and also the mis-printed "I know what they mean but that aint what they said". As always, I appreciate your input.
'04 220 w/'01 KX250 USD forks, '02 RM125 Showa shock, Rekluse EXP 3.0, LHRB & all RB'd
Post Reply