KDXRIDER.NET

Banana944 wrote:Hey SS109, do you know what clevis they used on your rear shock? Id like to upgrade my rear as well, but like you, don't like the idea of shortening internally and losing stroke.

Sorry, forgot to get in touch with my suspension guy until today. He says he can't remember for sure but believes he used one off of a DRZ400.

So I got my suspension back from Don today. How exactly do I determine how much the forks need to come up in the triples to match stock geometry?

Fun Wheel Drive

Compare stock suspension travel to new suspension travel. My new suspension has 1" more travel so i started with them raised 1" in the clamps. It's not 100% accurate but gives a good starting point. Remember, raising or lowering the forks in the clamps is a tuning tool. There is no absolute correct number for any bike/rider combo. You just have to try it and see if it turns well and is still stable at high speeds. If it turns great but is unstable/twitchy at high speeds then lower the forks in the clamps. Stable but turns slow/pushes raise the forks in the clamps. Always make adjustments in no more than 1mm increments as that slight difference can change handling characteristics dramatically.

Also, make sure your rear sag and spring are correct before setting the new front end as the rear does affect how the front handles.

Looks like the specs have exactly the same length on these forks! Win!
Guess I'll have to learn how to set sag properly, though. And the shock is a mess, looks like a rebuild or replace is in order.

Fun Wheel Drive

So my 92 with the 49mm Showa conventionals is all put together and humming along.
Got my 93 with stock USDs working well also, and find myself preferring to ride the 93.
Why? Well I'm in 1st gear goofing around tight cactus surrounded trails in my yard, and it feels more nimble.
Interesting.
A quick measurement from top of triple to center of axle on each showed that the Showas are sitting about 1 1/4 inches higher.
You guys were right. Should I have had them internally shortened while being serviced? Too late now. What to do..

"Good job, guys. "

yes you should and I know some people on here say usd are better but those conventional showas you have are considered some of the best forks ever made when set up right for you. When you get them to the right length bike should be more nimble

osobad wrote:yes you should and I know some people on here say usd are better but those conventional showas you have are considered some of the best forks ever made when set up right for you. When you get them to the right length bike should be more nimble

USD sure looks cool! My sus guy said the same about these being some of the best forks out there, but they got dwarfed by the new cool looking USD that was all the rage.
If they don't work out on the kdx, I might swap them onto an xr650r BRP.

"Good job, guys. "

MX forks that are not internally shortened or pulled up can leave the ol' KDX riding like this:

Of course it handles slow. You have effectively turned your bike in to a dirt bike chopper by raising the front end. Just slide them up in the clamps to get them to match the stock geometry. If they hit the bars then put some bar risers to get the necessary clearance. Mine are slid up 1" above the clamp to get the geometry right.

SS109 wrote:Of course it handles slow. You have effectively turned your bike in to a dirt bike chopper by raising the front end. Just slide them up in the clamps to get them to match the stock geometry. If they hit the bars then put some bar risers to get the necessary clearance. Mine are slid up 1" above the clamp to get the geometry right.

I've got the risers already, but I can only slide them up so far before the fork tapers a little. Still, it'll be a step in the right direction.

"Good job, guys. "

it was marketing more than any thing that killed the production of these forks, if possible have the shortened internally. These forks track through the rough stuff better than any fork I have used and I have used some good forks. KTM guys were using them for a while also

I disagree that it was mainly marketing that sold USD forks as better. Why? Because they are better.

USD forks have less flex which are much better (ie; safer) at handling high speed hits that will upset most conventionals that could result in a serious crash. Next is the real advantage of less underhang. Simply put, they are narrower at the bottom compared to any conventional of the same size (43mm USD vs 43mm conventional). This is very beneficial when dealing with deep ruts and rock gardens. Lastly, USD forks have less unsprung weight. Anyone who is familiar with suspension tuning on anything with wheels knows this is a huge plus. Less unsprung weight makes it easier to tune a given suspension system for the conditions it is meant to encounter.

Now, about the disadvantages to USD's. The biggest is that USD's carry their weight higher on the bike. The higher weight is carried on a bike the more it negatively affects handling. Then we have maintenance cost. USD's tend to need to be serviced more often but the cost to do so is on par with conventionals. Lastly, the fork tubes (the surface the seals ride on) are more likely to be damaged which can cause fork oil leaks and/or needed replacement of the tube.

In conclusion, the manufacturers believe the USD's pluses outweigh their negatives and I agree with them. I will not ride any dirt bike with conventionals unless I'm literally planning on just put-putting around. Once speed increases, and/or terrain becomes rough with rocks or whoops, USD's are the only choice IMO.

Thanks for the input, SS, but what about the biggest bonus to USD: They look positively boss :)

"Good job, guys. "

While your points are valid we are only talking about the Showa Twin Chamber Conventional forks. Not most of the standard conventional forks. And we are talking about woods or off road. I do have a good understanding of suspension and in my opinion and many others including some very good tuners these forks just flat out work for the type of riding( non high level super or moto x) Very very forgiving fork and not a lot of flex, slightly more than Good USD . Not going to get into the open chamber vs Twin chamber discussion LOL. No disrespect meant to anything said by the way its just a discussion . And in the beginning it was some marketing involved because the USD just looked cooler but were not better than these particular forks

osobad wrote:While your points are valid we are only talking about the Showa Twin Chamber Conventional forks. Not most of the standard conventional forks. And we are talking about woods or off road. I do have a good understanding of suspension and in my opinion and many others including some very good tuners these forks just flat out work for the type of riding( non high level super or moto x) Very very forgiving fork and not a lot of flex, slightly more than Good USD . Not going to get into the open chamber vs Twin chamber discussion LOL. No disrespect meant to anything said by the way its just a discussion . And in the beginning it was some marketing involved because the USD just looked cooler but were not better than these particular forks

No disrespect taken. Like you said, just a discussion!

Back to that discussion... thing is that today USD forks are clearly superior to even the last conventionals including the Showa twin chambers. As good as they were, they still have the underhang, unsprung weight , and flex. Sadly, the more you try to reduce flex in conventionals the worse the underhang and unsprung weight become. That is why they have gone away and USD forks have fully taken over for every brands best bikes.

BTW, why has this become a hijack of my conversion thread to discuss conventional forks and other installs?

SS109 wrote:

osobad wrote:While your points are valid we are only talking about the Showa Twin Chamber Conventional forks. Not most of the standard conventional forks. And we are talking about woods or off road. I do have a good understanding of suspension and in my opinion and many others including some very good tuners these forks just flat out work for the type of riding( non high level super or moto x) Very very forgiving fork and not a lot of flex, slightly more than Good USD . Not going to get into the open chamber vs Twin chamber discussion LOL. No disrespect meant to anything said by the way its just a discussion . And in the beginning it was some marketing involved because the USD just looked cooler but were not better than these particular forks

No disrespect taken. Like you said, just a discussion!

Back to that discussion... thing is that today USD forks are clearly superior to even the last conventionals including the Showa twin chambers. As good as they were, they still have the underhang, unsprung weight , and flex. Sadly, the more you try to reduce flex in conventionals the worse the underhang and unsprung weight become. That is why they have gone away and USD forks have fully taken over for every brands best bikes.

BTW, why has this become a hijack of my conversion thread to discuss conventional forks and other installs?

So that people can make informed decisions when following your example!
I for one am very grateful for all the useful information on here. Best thread Jack I've seen in awhile

"Good job, guys. "

Friedom wrote:So that people can make informed decisions when following your example!
I for one am very grateful for all the useful information on here. Best thread Jack I've seen in awhile

True that!

BTW, will be out riding Marana 6am on Sunday if you're interested.

SS109 wrote:

Friedom wrote:So that people can make informed decisions when following your example!
I for one am very grateful for all the useful information on here. Best thread Jack I've seen in awhile

True that!

BTW, will be out riding Marana 6am on Sunday if you're interested.

Mud!
Sounds fun, but busy weekend. Plus I have to change a rear flat.

Say, while we're off topic - how do you change the clutch lever seal? Haven't figured out how to get the actuator shaft out of the case.

"Good job, guys. "

SS109 wrote: ↑08:25 pm Jul 31 2022 The one series of shock that will fit, as I have one on my own bike, is the '01-'06 Suzuki RM125 Showa shock with a lightly modified XR400 lower clevis but this mod isn't for everyone.

@SS109 so it's an XR400 lower clevis? For some for some reason I thought I had read you saying it was a DRZ400 lower clevis, and I had a bunch of the two different shocks pulled up on ebay, the RM 125 and DRZ400, and I couldn't tell any difference in the length on the clevis between those two, they look like they could be nearly identical but I thought maybe there was a subtle difference in length I just couldn't determine from the photos?
And I couldn't find a DRZ 400 shock for less than a hundred bucks.

I've got some RM125 Showa Twin Chamber 49's coming, and I wanted to match it up with one of those 125 shocks the way you did it, so that it's almost the right length. I'd rather not have to internally lower it substantially. Plus it comes already sprung for my weight! The stock KDX spring, although a better color choice, is technically a little bit too firm for my 150lb weight according to the Race Tech spring rate calculator, although I do quite well with it on a rebuilt shock in the nasty gnarly rocky Appalachian singletracks.
I'll be rebuilding my first KDX, a 99 220, this winter, and looking to make it the ultimate singletrack machine in order to spare the purple plastics on my 97 220 from severe trail abuse and carnage...

Yeah, XR400 is what my suspension guy said. For the record, I do have my forks slid up in the clamps by about 30mm IIRC. At 150lbs I would be running either .38/4.8 or .40/5.0 on fork/shock springs. I only went with .40's on the KDX forks because of having them slid up in the clamps so much but stuck with a 4.8 on the rear. BTW, I'm 140lbs.