USD Forks KYB 43U, 46U, or 48U?

Got questions? We got answers....
Post Reply
SOARSKI
Supporting Member I
Supporting Member I
Posts: 60
Joined: 02:00 am Aug 16 2009
Country:
Location: MO

USD Forks KYB 43U, 46U, or 48U?

Post by SOARSKI »

I don't think I did my homework as well as I should have. Im wanting to do a USD fork conversion and have a set of 96 kx 500 forks with rim. When I bought these six months ago I didn't realize these were a 43mm fork. I bought them because they were(I think) a direct fit to the KDX.

This is what I found, correct me if I'm wrong:

KYB 48U
- KX 125 2002-2005
- KX 250 2002-2005

KYB 46U
- KX 125 1996-2001
- KX 250 1996-2001
- KX 500 1997-2004

KYB 43U
- KX 500 ?????-1996

I'm wondering if I would be better off going for a KYB 46U or 48U? Any big advantages such as performance, getting parts and finding good info to rebuild the forks myself. I can find videos on rebuilding 46U and 48U but not 43U which is helpful for a first timer like myself.
User avatar
Julien D
KDXRider.net
KDXRider.net
Posts: 5858
Joined: 07:53 pm Nov 07 2008
Country: USA
Contact:

Post by Julien D »

That looks about right to me. I wasn't entirely sure what year they swapped to 46 from the 43's, but I'm pretty sure the 97 had 46's.

I would think the 43mm KYB USD's will be good forks for a KDX. Perhaps not as ideal as something newer, but still darn good forks. The rebuild will be pretty much the same as with the other forks, so using that video and an exploded parts diagram of the 43's should be all you need.

Also yeah, If you have the front end with triples and all, it should just bolt into your steering head.
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 »

I had a friend with a KX500. How he set up those forks, I'm not real sure, gold valves and someone set up his shim stack. Anyway, that was the plushest front end I've ever ridden. So smooth! If I were to set up a KDX, those are the forks I'd use. Bigger is fine if you're hitting big air on MX tracks I suppose, but for trial riding, I think the 43's would be best.

****EDIT****
I remember now; he bought gold valves and had the local Race Tech shop install them and set up his forks. He discussed the type of riding he did, trail bike, single track technical interspersed with some fire roads for quicker stuff.
Last edited by skipro3 on 10:38 am Jan 25 2010, edited 1 time in total.
Jerry

I'd rather be a smartass like carvr, than a dumbass like.... well, you fill in the blank!
river
Supporting Member
Posts: 60
Joined: 11:34 pm Dec 13 2009
Country:

Re: USD Forks KYB 43U, 46U, or 48U?

Post by river »

>|<>QBB<
SOARSKI wrote: I can find videos on rebuilding 46U and 48U but not 43U which is helpful for a first timer like myself.
Would you terribly mind sharing where you found those videos? I could use looking at those in a big way. Thanks much...
SOARSKI
Supporting Member I
Supporting Member I
Posts: 60
Joined: 02:00 am Aug 16 2009
Country:
Location: MO

Re: USD Forks KYB 43U, 46U, or 48U?

Post by SOARSKI »

>|<>QBB<
river wrote:>|<>QBB<
SOARSKI wrote: I can find videos on rebuilding 46U and 48U but not 43U which is helpful for a first timer like myself.
Would you terribly mind sharing where you found those videos? I could use looking at those in a big way. Thanks much...
http://www.motopowervideo.com

I don't have the fork or the shock video but maybe someone can chime in as whether they are worth buying or just relying on other sources.

I do have the Basic Maintenance video and I thought it was good, especially for new guys. I also have the Carb video. I'm not sure I like it as much, I still haven't decided. I think there is some good guides on jetting out there. I would use a jetting guide and info found here in addition to the video for jetting. I think there may be some video on youtube and some other sites like racetech for suspension. The Videos by Motorpower are for specific model shocks. I like this because I've never touched the internals of a fork before.
User avatar
Indawoods
Creator and Founder
Creator and Founder
Posts: 9951
Joined: 09:59 am Jun 12 2003
Country:
Location: Midwest

Post by Indawoods »

Guess you haven't explored this site much eh?
*** Administrator //***
****'95 KDX 200/****

"People ate cows a thousand years ago for the same reason we eat them now. Cause they are easy to catch.We're not savages,we're just lazy. A cheetah could taste like chocolate heroin. But will never know. Those bastards are fast!!! "
SOARSKI
Supporting Member I
Supporting Member I
Posts: 60
Joined: 02:00 am Aug 16 2009
Country:
Location: MO

Post by SOARSKI »

>|<>QBB<
Indawoods wrote:Guess you haven't explored this site much eh?
I'm workin on it. Its not from a lack of effort. I just got finished reading about 75% of the General Q&A. The MF is loooong. Maybe I'm just not very efficient. I always feel like I'm going to miss something with the search engine.

I'm currently working my way through the fork conversion threads. So much info,new terminology etc., ADD?

I'll eventually catch up. Feel free to point me in the right direction and I'll read it.
User avatar
Indawoods
Creator and Founder
Creator and Founder
Posts: 9951
Joined: 09:59 am Jun 12 2003
Country:
Location: Midwest

Post by Indawoods »

There is a section on Jetting and a section on Suspension...

It is all I have ever needed as far as how to....
*** Administrator //***
****'95 KDX 200/****

"People ate cows a thousand years ago for the same reason we eat them now. Cause they are easy to catch.We're not savages,we're just lazy. A cheetah could taste like chocolate heroin. But will never know. Those bastards are fast!!! "
river
Supporting Member
Posts: 60
Joined: 11:34 pm Dec 13 2009
Country:

Post by river »

Alright dang it, sounds like a challenge. I'll find them videos if I'm here all night.
User avatar
Colorado Mike
Gold Member
Gold Member
Posts: 1921
Joined: 11:42 am Feb 25 2005
Country:
Location: Colorado

Post by Colorado Mike »

Just a quick note on Ski's assessment of KX500 forks. I have no idea how the forks on that bike can be judged, since the ones I have ridden only have the front tire on the ground once every 50 yards or so. They are like jet skis made for dirt. Apparently there are people that can control the right grip on a KX500, I am not one of them.


I want one bad. :supz:
Mike

Life's tough, it's even tougher if you're stupid.
'04 KDX220
User avatar
Indawoods
Creator and Founder
Creator and Founder
Posts: 9951
Joined: 09:59 am Jun 12 2003
Country:
Location: Midwest

Post by Indawoods »

>|<>QBB<
river wrote:Alright dang it, sounds like a challenge. I'll find them videos if I'm here all night.
Not videos... you actually have to read. :grin:
*** Administrator //***
****'95 KDX 200/****

"People ate cows a thousand years ago for the same reason we eat them now. Cause they are easy to catch.We're not savages,we're just lazy. A cheetah could taste like chocolate heroin. But will never know. Those bastards are fast!!! "
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 »

>|<>QBB<
Colorado Mike wrote:Just a quick note on Ski's assessment of KX500 forks. I have no idea how the forks on that bike can be judged, since the ones I have ridden only have the front tire on the ground once every 50 yards or so. They are like jet skis made for dirt. Apparently there are people that can control the right grip on a KX500, I am not one of them.


I want one bad. :supz:
When I rode it, I had a strong sense of self preservation. Actually, the throttle was very controllable I thought. This KX500 was specially modified; it had a compression release to ease kick starting. But not just any compression release. This one was mounted on the back of the cylinder just above where the carb bolts on. This release kicked in after the piston traveled about 125cc's down into the barrel. To start the bike, you pull in the compression release lever mounted near the clutch lever. Hold it in and kick start the bike like usual. You feel the resistance equal to kick starting a 125. Once the bike starts, you can release the compression release any time. The bike will start and remain running with the compression release pulled in since it does have that 125cc's of power. This release mount above the carb goes through the cylinder's water jacket and is quite unique.

The KX500 also had an auto-clutch.
Jerry

I'd rather be a smartass like carvr, than a dumbass like.... well, you fill in the blank!
river
Supporting Member
Posts: 60
Joined: 11:34 pm Dec 13 2009
Country:

Post by river »

>|<>QBB<
Indawoods wrote:>|<>QBB<
river wrote:Alright dang it, sounds like a challenge. I'll find them videos if I'm here all night.
Not videos... you actually have to read. :grin:
OK, well I'll find that then.

What I would really like to find is just one good picture of the inside of a fork that makes it clear what all the inside bits do. I spent a good bit of time searching one night with no luck.
User avatar
scheckaet
KDXRider.net
KDXRider.net
Posts: 3740
Joined: 12:09 am Nov 10 2005
Country:
Location: edmond oklahoma

Post by scheckaet »

check this, helped me understanding a bit of what does what in the fork. http://www.kdxrider.net/forums/viewtopi ... hth+height
As for pics, check the usd kayaba sticky in the fork conversion, there is a few pics
river
Supporting Member
Posts: 60
Joined: 11:34 pm Dec 13 2009
Country:

Post by river »

>|<>QBB<
scheckaet wrote:check this, helped me understanding a bit of what does what in the fork. http://www.kdxrider.net/forums/viewtopi ... hth+height
As for pics, check the usd kayaba sticky in the fork conversion, there is a few pics
Thanks!
User avatar
fuzzy
KDXRider.net
KDXRider.net
Posts: 3437
Joined: 01:29 pm Jun 18 2003
Country:
Location: Fredneck, MD

Post by fuzzy »

Pretty cool Jerry. Seems being able to find TDC, good jetting, and just give a 500 a gook whack and they light right up. Of course stuck on a hillside or something would be nice to have such a convienince. I love the power of a 500...The grunt anyway. Just needs a 2 turn throttle cam :mrgreen:
'91 KDX 200 Project $300 KDX
'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
Post Reply