[micahp]

I am running a brand new and completely stock KTM 525 SMC (Basically an SX with wheels and brakes). My last time out I was running Dunlop slicks with about 20 psi front and rear (cold day). There are a couple of problems I am running into on suspension setup:

01) Front end chatter when off the throttle through fast turns. Moment I get back on the throttle the chatter disappears. I am *NOT* getting any chatter on the brakes in a straight line (if that makes a difference).

02) It turns in slower then I would like. Very neutral to slow steering. I would prefer to have it "fall" or "dive" into the corner.

03) The balance front to rear is more biased to the rear during the mid to corner exit then I would like. I would prefer the rear to step or push coming out of the corner (right now the front is pushing).

I have some ideas on what todo about these problems (i.e., some more weight on the front end by increasing rear preload and/or dropping the front forks slightly). But I am pretty certain I can dial a lot of this out through the front & rear dampening (I actually had someone do this for me on my old XR650) -- but I don't have a clue which way togo on dampening setup. Ideas????

-Micah

 

[rhyne]

i'm having a lot of the same problems ('03 KTM 525). raise the forks in the triples as much as possible. I'm actually trying to find or fabricate a riser for the bars to allow the front to drop a few more mm's than is possible now. it's either that or have the suspension re-sprung and valved and lowered an 1" or so. as for the dampening/preload settings, i don't know.

 

[brian]

You have my answer........

Hey Rhyne !! Check out Pro Taper's new adjustable triple clamps with the offset bar clamps........ only problem I see is by the time you get the bars outa the way and the forks up your riding position may suck...... I'm gettin shortened forks :thumbup:

 

[kpracing]

More weight on the front (raise the forks, more ride height in the back)
Try when the bike does push to lean forward.
Also you want your wheels to be close together for fast turn in (chain adj all the way in)
:thumbup:

 

[bdmmotard]

you can try what those guys said, but i'd make the rear a hardtail and rake out the front a couple feet. turns in great!

i like starting with raising the forks as much as possible, giving the rear 60mm sag, and stiffining the front just so that it doesn't dive. you can get quicker turn in by stiffining the rear but it might end up pushing the front wheel mid turn.

 

[High Speed]

Make sure you are sitting way forward on the seat to keep more weight on the front.

 

[FastForwardRacing]

Also you want your wheels to be close together for fast turn in (chain adj all the way in)
:thumbup:

Shortening the wheelbase does two things. It lowers the rear(transfers more weight to the rear, taking from the front) and by moving the wheel farther forward, it also transfers more weight to the rear, taking weight off the front. Result...more chatter!

 

[micahp]

i'm having a lot of the same problems ('03 KTM 525). raise the forks in the triples as much as possible. I'm actually trying to find or fabricate a riser for the bars to allow the front to drop a few more mm's than is possible now. it's either that or have the suspension re-sprung and valved and lowered an 1" or so. as for the dampening/preload settings, i don't know.

Ok, good, I'm not crazy for wanting to drop the front. I had a couple of people trying to convince me that it could all be tuned out by dampening alone -- which it might -- but it certainly won't solve all the handling problems I am having, esp. the slow turn in.

I've tried weighting the front as much as possible with my body and it doesn't seem to help (and you can get practically over the front axle on the KTM).

Reading the John Robinson book "Motorcycle Tuning: Chassis" he seems to indicate that the particular chatter i'm getting is caused by over extension in the rebound. Basically an oscillation in the first couple of inches of suspension movement that is not being properly damped out. I believe that getting on the throttle cures it because the suspension is not trying to hammer itself back and forth in the pavement (when in doubt gas it out). So I am hoping that incrementally increasing the rebound and compression up front will cure this badness... (or just holding open the throttle )

I am also going to experiment with different tires. I don't like the Dunlop slicks. They don't seem to have enough "give" and they seem "stiff" -- the transition from grip to slide is very sudden. And I am thinking the tires have a bigger effect on my handling especially in the first couple of inches of travel (and actually according to John Robinson the tires absorb almost half the force input into the suspension -- at least according to his calculations -- could be why the 16.5" front with the taller sidewalls are becoming popular). Anyways I am going to try out the Maxxis intermediates and start dialing in my suspension from them...

 

[High Speed]

Anyways I am going to try out the Maxxis intermediates and start dialing in my suspension from them...

If you don't like Dunlops, your gonna hate Maxxis.

Try Michelin's

 

[micahp]

If you don't like Dunlops, your gonna hate Maxxis.

Try Michelin's

Whats the difference between them all? I've run Maxxis on my XR and they seem to work fine -- for me at least. Just wear out *very* quickly. Sunday was my first time ever on slicks and they seem to have taken forever to warm up and once they broke loose they slid really quickly (throwing me on the ground twice). Granted when they were warm it took a *LOT* to break them loose. But I would imagine a novice like myself would prefer something that was a bit more loose and but also more predictable. Plus what about my "theory" that the Maxxis tires with there tread would provide better dampening characteristics and possibly help cure the chatter problem? Or am I just talking crazy talk?

 

[High Speed]

Whats the difference between them all? I've run Maxxis on my XR and they seem to work fine -- for me at least. Just wear out *very* quickly. Sunday was my first time ever on slicks and they seem to have taken forever to warm up and once they broke loose they slid really quickly (throwing me on the ground twice). Granted when they were warm it took a *LOT* to break them loose. But I would imagine a novice like myself would prefer something that was a bit more loose and but also more predictable. Plus what about my "theory" that the Maxxis tires with there tread would provide better dampening characteristics and possibly help cure the chatter problem? Or am I just talking crazy talk?

Dunlops are light years ahead of Maxxis.

Were you using the KR106 front and KR108 rear? That is the suggested supermoto tire

Where they the soft compound?

 

[SlowSlide]

As for your chatter problem, make sure your damping settings are alike side to side. If one leg is different than the other, it could cause an oscillation. Also, the chatter could be caused by the forks "packing", meaning they hit a bump, and don't rebound quickly enough to follow the pavement. You don't want a bunch of rebound for motard like you would for MX. Control the front end by adding compression damping, making it slow down hitting a bump, rather than just pushing all the way thru the travel.

Take notes on your changes, you could always start over again where you are now.

 

[micahp]

Dunlops are light years ahead of Maxxis.

Were you using the KR106 front and KR108 rear? That is the suggested supermoto tire

Where they the soft compound?

I'm not exactly sure. They were what came stock from the KTM factory for the bike which I beleive is the 555 soft compound front and rear.

I do admit that they day was cold and moist on a green track. The first time I crashed I was running 24psi. Which I latter dropped down to 20psi -- which improved grip and handling tremendously -- but still wasn't comfortable on them.

This may be a stoopid question: but how exactly are the Dunlops light years ahead of Maxxis? Obviously the Dunlop R&D budget is probably 10-100 times bigger then Maxxis. And I'm sure there is not one top 5 AMA pro-rider running Maxxis (I'd imagine). But I could imagine that at the novice or even intermediate level outright grip is not everything -- where it might be for a pro rider.

 

[brian]

The fast guys will tell you to raise your forks through the clamps till the bike gets twitchy on the straights.... I watch some of these guys and wonder If sometimes they go alittle far.........then again on faster tracks they prolly go the other direction for better stability.... :hmmm: just as an example my KX has factory lines/marks on the upper fork, I'm down 7 mm, on a bumpy straight stretch I get a little wobble when the front tire touchs the track, on the corners my front tire is always planted even in the wet, what I am learning now is to work my weight back and forth with body position (thanks #99).... I've lowsided twice at speed and the back end always kicks out.......??? I dunno.. I rather the rear than the front :headscrat
oh yea... on wet tracks or cold temps I get down to 16-18....Pirelli rains and Avon SM's.........bike weighs 220 and me "with gear"... 250 ???
So far I'm at 100mm rear sag... compression and rebound at rear are 3/4 of the clicks... front compression is all the way and rebound is 3/4 of the way...... :hmmm: seems to work... still experimenting :hmmm:

 

[husky450]

For what it's worth, it sounds like a compression/rebound problem. As was mentioned, make adjustments and keep copious notes.

As for the turn in, yes, lower the triple clamps OR raise the rear end.

Good luck.

 

[FastForwardRacing]

""As for your chatter problem, make sure your damping settings are alike side to side. If one leg is different than the other, it could cause an oscillation.""

Untrue...it is not uncommon to run different setting on each fork to find a "medium" setting.

""No top 5 rider on Maxxis".

Burkhart has made the Podium(So.Boston) on Maxxis and was 4th in points going into Vegas.

Maxxis has shown a commitment to SM as their tires are purpose built. A 16.5 is in the works for '05. Yes I would amagine Dunlop and the others are ahead of Maxxis in developement thru their years of RRing, but to say the maxxis don't work is ludicrous.

I believe 100mm of sag is too much for a SM. We only run 60-65 depending on the track.

Tdub

 

[Niggo]

we are one of the best suspension tuner in germany (www.rs-racing.de) and guys like künzel and nearly all top ten riders in germany trust in our work! also we had top ten riders in der S2 WM

the problem with the SX and SMR Bikes from KTM is the soft front frame! the 2004 models have stronger frames and the chattering wont be any problem.

you can try clamps with 14mm offset, it would be much better! we do have our own clamps, whith this one you can change the offset in 30 seconds from 12 to 16mm :thumbup:

using 16,5" front wheel with 80 circle cut will help, too! maybe your fork is to progressive!? the original SX suspension need much more Rebound, too...
their are many things to change on the suspension, i thin a serious tuner will help you

oh, i think sag means "durchhang"
the PDS damping system at the rear needs 18-22mm sag without rider! at the front circa 35-40mm :thumbup:

greets from germany

 

[Big Zero]

I had a chattering problem with my 426 when I first got it switched over to Supermoto trim. I had a guy tell me that I needed to stiffen the compression on the front to nearly as stiff as it would go. I then, needed to soften the rebound to a very soft setting. This allows the tire to track back tothe track quicker and also prevents the front from diving when entering corners. The rear was to be set up opposite of the front with the compression set soft and the rebound set stiff. I also played around with tire pressure and when I put all this info into use, my chattering problem went away.

I don't know if this info will fix the problem with the KTM, but it sure helped me to feel more confident going into corners.

The guys have given you a lot to sort through on this thread, so be patient and see what works.

Good luck

Paul G

 

[High Speed]

Fast guys are fast on anything.

If riders had a choice and/or money did not matter, I doubt Maxxis tires would be on there bike.

They are supposed to be getting better and there commitment is there. As of right now it's not my choice of tire.

I think most of the european guys run Michelin. Going to have to try them soon.

 

[High Speed]

This may be a stoopid question: but how exactly are the Dunlops light years ahead of Maxxis? Obviously the Dunlop R&D budget is probably 10-100 times bigger then Maxxis. And I'm sure there is not one top 5 AMA pro-rider running Maxxis (I'd imagine). But I could imagine that at the novice or even intermediate level outright grip is not everything -- where it might be for a pro rider.

As soon as I put Dunlops on my bike it eliminated frontend chatter and push while going much faster. If it keeps me on the bike and off the pavement, its worth it.

Outright grip IS everything :hammer: