2002 Ktm

[Jeremy Wilkey]

While I could have posted this up 4 mounths ago.... Here is a quick look at the 2002 KTM SX suspension. The bikes have increased fork spring rates which are very good things for the average demographic. The externally adjustable fork preload and 48mm tubes are very good improvments as well. Internally the 48's are simmlair to the 01 the major difference being a redisgined spring guide.

The shock on the other hand is a dramaticallt improved unit. The 2002 SX shock is much improved in almost all aspects. The forged upper body fetures improved oil passages.

The 1998-2001 body is on the right.. The 2002 body is on the left, note the moredirect and larger passage. For the record I don't actually think this is such a big issue..

 

[Jeremy Wilkey]

Compression adjuster

The 1998-2001 Adjuster may have been an issue.. We have found that modifing them does improve responce of the shock "Slighlty" My WP Rep Richard Swaitskas and I have had really intresting discousions about these peices.. I've learned somethings by others sudgestions, but I'm still not completly convinced that the 2002 Adjuster offers any signifciant inapropraite damping character.. Only time and testing will tell...

The top adjuster is the old style. Notice the 8 small inner holes.. These are the compression holes.. A failry small area even for a slow moving shock..


The midle valve is the adjuster for the EXC models.. This adjuster is very similar to the SX model.. Only the highspeed tensioing is fixed..

The botom adjuster is the Sx model with it's adjustable tensioniong..

 

[Jeremy Wilkey]

The Pistons..

The new shock features a improved communication between the primary and secondary piston. These larger reduce any potential for damping overlap. The larger holes actually allow more radical damping changes as they will still provide enough area of taller or shorter stacks are used..

 

[marcusgunby]

jer do you think in future the best upgrade to the older shocks will be a straight swap to the new version?it sounds like the older PDS has issues that only fairly major re-engineering will fix.

 

[Greg in Oz]

Jeremy,
We will be racing '02 Katooms and have been offered SXS Forks and Shock from the race department. The price is pretty good ( cheaper than Öhlins ) but is there any need for them. Do you know the differences apart from the 26mm axle and leg coatings?

 

[marcusgunby]

As far as im aware the 02 stuff is virtually SXS so you wont gain much.The olhins shock works very differently as the 2nd piston is much smaller than the primary piston and has no affect until the last part of the stroke.So basically its a single piston shock(less friction) until it almost bottoms out.The Ohlins also uses std size shims/shaft etc so its easier to tune for the average joe.However the price isnt cheap so you must decide if its worth it.

 

[johnpace2]

Hi Jeremy,

This is a relativley low tech question, but I have a 2002 125 SX and have heard the front forks are prone to leaky fork seals. Is there anything I can do to prevent/minimize this?

Thanks!

John

 

[Jeremy Wilkey]

Greg,
I'm not sure if your talking 02 SXS or 2001 SXS.. The 2001 SXS is very simliar to the 2002 production. The TI coating improves fork action slightly but beyound that it's a toss up from my standpoint..


The 2002 SXS is going to be blinging... The resivor piston has gone up in Diameter so there is less knose pressure on the shaft. Also the larger axle and triple bushing fork is very cool..

Anyway the 2002 forks donm't have any sela problems that I'm aware of.

Marcus,
I don't actually have much of an issue with the older PDS shocks when they are modified.. I agree completly that the new shocks are better but I don't really think it's such a big deal.. now 2002 SXS well that is better...Marcus remmber the big fade issues you where having... I need to get my PDS pump..

Greg,
On the Ohlins.. I "Doubt" the ohlins is worth the money.. Now I have heard crediable people tell me that it is very good... But i think the reworked SX shock is just fine.. probalby much better.. (BTW I need to speak with you..)

You know I missed a major point.. The 2002 pistons are more low flow in concept.... Pretty cool design actually..

Well I think that covers this for now..


Jer

 

[Greg in Oz]

Jer,
Sorry, 2002 was the subject. Actually we are now getting a complete SXS 540 from KTM. So that's that settled.

 

[Bud-Man]

Jer,
Cool stuff. If you get any of the '02 SXS stuff apart can you post some pictures of the "improved" pieces and go over them from a technical stand point. I find that stuff very interesting. It would also be nice to throw in an Ohlins PDS shock for comparison purposes as they use a different approach than WP and I think it would make a really cool thread. The PDS shock is kind of unknown territory for most people and we could all learn from the technical discussion!

 

[marcusgunby]

Jer thanks for you reply.I must sound like ive got a 'thing' against the pds.I suppose i have in a way as it caused me soo much grief but i would love to get my hands on a fully modded one to see how it performs-care to send one over with a 02 125sx to try it on?:D Am i right in thinking you have also found a fade issue that was caused by air trapped in the shock that was unable to be bleed out in the normal way?:eek: Do you know how the pump attaches and works?ive never seen one.

 

[John Curea]

Marcus
Send me your email add, and I will sen you some cool info on the pump.

 

[lawman]

hey johnpace, my '00 exc, run hard thru all kinds of nasty enduro conditions, has yet to blow a fork seal. the key: fork booties from holeshot. they're cheap & a breeze to install.

 

[Bud-Man]

Lawman,
Your bike uses a different seal than the '02 SX line (43mm vs. 48mm). I've seen a couple of new SX's with leaking seals and little time on them. Heck, my freind's '02 250sx needs fork seals after 6-8 rides and his '01 520 made it through most of a year! Curious to see if this is an isolated thing or a potential problem.

 

[marcusgunby]

Ive been thinking about the PDS recently and decided its a flawed design.
heres why:
1 it uses different springs to every other shock(read expensive)
2 it has more friction than others
3 it needs mega quality oil to help it live
4 it has different shim sizes to other shocks
5 due to its steel construction it doesnt seem as good as others at getting rid of heat
6 i dont like the idea of the oil running through the centre of the shaft before the bottoming needle comes into play(better to somehow run on the outside of the piston)
7 it needs all sorts of mega priced 'special tools'-latest is a pump that when using on later shocks 01,02 you have to remove the rebound needle thats in the centre of the rod(IMO only because its the only way the pump will still work)
In conclusion i dont think the PDS system is crap just WP version of it.
All that to do away with a couple of links and bearings. :(
I like the ohlins idea(2 different size pistons)so the 2nd only comes in for bottoming control.
My idea would be to use a bottoming cone like on a fork instead of the 2nd piston
Let the debate begin:p

 

[nikki]

I rode a new '02 KTM 125 SX at Byron this sunday - it was brand new and brought out to test ride. Red mentioned that the fork seals were already leaking on it. I didn't notice but he did. It also gave me headshake in about 4-5 spots on the track (new test ride '02 KX 125 and my '01 YZ 125 had none) but maybe it was because of the leaky seals or bike set-up geometry? :think

 

[Jeremy Wilkey]

Marcus,
Your killing me! I think the PDSis the colest thing since sliced bread.. To the point where although adimtalty gives me fits at times ... Screw tools (i've bought them).. althought some still have not arived.., screw shims...I) made all the sizes (about 30,000 shims total quanity), screw springs...(I buaght them in 10 diffent rates in qunaity). It has been a excersice and that out of the box thinking flat rocks..

I love a chase/challange.. I like the hassle of work and reward to look into the face of a crazed engineer and go I got your bag baby and I love it.. :p

Regards
Jer

 

[Bud-Man]

Marcus, I couldn't agree with you more. Especially after I've spent some time working on the Ohlins PDS.
Believe me I don't miss the linkage and the maintenance it requires :D !!!

 

[Flying Rhino]

2002 KTM ,Backyard Techs and things to come.

It seems to me that the this PDS issuse may come from its different approach and its challege.


Look there was a day when a monkey with a wrench in his hand could work on a car, fix an engine or even fix his refrigerator. As technology advances it becomes both easier and more complex, more costly and cheaper.Fields of expertise become more and more specialized, hence the backyard mechanic(hack) is gone and replaced more and more by highly technical qualified people specializing in that field. I guess my point is embrace the complexity and challenge in new technoligies, ways of doing and designs, in suspension that require advanced understanding or pony up the money and study time to become a specialist or just pay to have it done by a specialist.

We as riders must identify and look at potential shortfalls or bad designs I agree but darn it in the case of PDS don't blame the engineers because it takes advanced understanding and money to become profiecent at dealing with its new challange. In the end good technoligies will last or become cornerstones for further growth,or their failures will be learned from and recorded.

Soon will come a day when the shade tree suspension tech does not have the knowledge, money or tools to enter the field. With nothing more than a nitro tank, a vice and friggin wrench and a couple of $49.95 how-to tapes.....he is fast going the way of the shade tree mechanic.

 

[svi]

Marcus,
I suspect your trying to generate discussion rather than suggesting that WP should scrap their development based on your arguments.
Perhaps you could expand on why having a steel body has poor heat transfer properties and what is wrong with oil running down the centre of the shaft.
You would be better basing your argument on engineering or damping principles rather than personal expense. If I was WP I would be quiet happy not to have everybody and his granny ripping my shocks to bits.

 

[marcusgunby]

SVI you got the idea-its about generating discussion.
Im not an expert but i was under the impression alloys dissapate heat very well and better than steel.The KTM PDS seems to get very hot during use and stays hot for a long time afterwards(ive not done any real tests-this is just from feeling a KYB and a WP after the same race)
As for the oil down the centre of the shaft-it IMO caused alot of problems in the 98/99/00 shocks as if they got really hot it caused the treadlock to break that holds the clevis on(this is not good-trust me)WP went to a convention system of no oil in the shaft on the 01/02.
I like the separation piston principal as it has a realibilty advantage over a bladder.
On the damping side i dont feel i have enough knowledge to be truthful, but so far bigger shafts on forks or shocks seems to make the valving more sensitive which some consider great,i find this to cause excessive testing/tuning but then that maybe because i have too little experience.

The arguement for the shocks specialised nature and not every man and his dog bieng able to work on it is a valid point.However this is fine, but the customer can suffer from this approach.Ive know plenty of people go to reputable tuners(big name-not pro action) and get very poor results.
Jer is to be commended for going into the PDS in a big way and doing the necessary ground work to get a good knowledge of the system-not many have.So as a customer who do you trust assuming jers not in your country?
Alot of the costs of the system ends up bieng passed onto the rider.

Let me add im not against the PDS system it could well be the way of the future but i just like the ohlins version better as it performs well and doesnt have some of the downsides of the WP shock.Let debate continue(if anyone doesnt understand any of the differences of the PDS shocks-please ask its very interesting from a suspension anaoraks point of view)
:cool:

 

[JTT]

Ok, I'll bite....Quote: (if anyone doesnt understand any of the differences of the PDS shocks-please ask its very interesting from a suspension anaoraks point of view)
Give it to me ;)

 

[marcusgunby]

I just wrote a very indepth answer then i had a computer problem and lost it all- i will reanswer if i get the energy or if no takes up the challenge-what do you know so far?

 

[JTT]

What I know about PDS could fit on a large postage stamp ;) I have never seen one apart and have no experience with even riding them...very few KTMs in this area.

Thanks

 

[Jeremy Wilkey]

Marcus,

The new shocks don't run the oil out the shaft any more.. This is a geat string.. And um.. Get typing :p

I don't want to do it!!

Jer