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02 KTM520SX - Playing with valving
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[QUOTE="Yoken, post: 566669, member: 25312"] Good day to everyone. First, I'd like to take this opportunity to thank Jeremy and the entire DRN team for sharing their passion with us... I've been enjoying these forums for quite a while now, and I thought I could also share with you my latest experiments... This 1st post is going to be a bit long, but I believe it might be of interest for some KTM riders out there. Well, here it goes. I'm the happy owner of a 2002 KTM520SX, which we all know doesn't have the best suspension settings in stock form. As I live in Cyprus for the moment (little island in the Mediterranean), I can't send my suspensions to Europe or USA easily for a revalve. There is no local suspension guru here either, so I decided to give it a try myself... first with the fork. The stock setting of the fork is a real nightmare for me! The ride is very tiring. No plushness for the 'choppy' stuff, yet not firm either to handle hard breaking (front-end dive) or hard landings (bottoming). Yes, and like many other KTM riders, I have to deal with headshake too... Here are the specs: The rider: 1m80 - 85kg - Fast intermediate The terrain: Mostly hard clay, dusty, slippery, with rocks. Flat or bermed turns (no ruts) and a lot of man-made jumps. The bike: With the stock valving and springs, I ended up with the following settings: - oil type: ATF - oil level 85mm (to fight bottoming, but it is harsh), - external pre-load 1 turn IN - LSC 32 clicks OUT (well, full 'soft'...which is not soft at all!) - LSR 13 clicks OUT (a bit slow to compensate the high oil level) - Front tire: Metzeler MC4 (intermediate) at 12 to 13PSI Stock BV stack (7x)24.1 22.1 20.1 18.1 16.1 14.1 11.25 18.25 Note: On both BV's, the needle circuit was partially obstructed (I would say as much as 30 to 40%) by the peening process on top of the nut. I had to drill it open to its original 3mm diameter. That could explain why the opening of the clickers didn't do much change! Stock MV stack Compression (4x)24.1, with a lift of 1.5mm Note: the 1st 2 shims (those that bottom against the rod end) were found heavily marked by the repeated impacts and bent. Rebound (4x)D.1 (D=delta shim, I think diam. 22mm... forgot to note...) 14.1 20.1 18.1 16.1 14.1 14.1 10.3 16.25 Now, I'm no suspension specialist. Not even close. So go easy on me here! According to data I collected in previous posts, it seems that I had to go in the following direction: better balancing BV and MV by - softening the BV stack for more LSC control, - reducing the lift on the MV stack so it kicks in sooner, - strengthening the MV stack to compensate for the softer BV. So not knowing really how to start, the 1st mod went like this: Modified BV MV compression MV rebound lift=0.5mm (3x)24.1 (3x)24.1 14.1 14.1 (4x)D.1 14.1 14.1 20.1 22.1 22.1 18.1 20.1 20.1 16.1 18.1 18.1 14.1 16.1 16.1 10.3 14.1 10.5 16.25 11.25 18.25 I decided to set the oil level first at 105mm (ATF) and tested the bike this morning. I can tell you that I went real slow on the 1st lap. Man, I was scared to fly over the bar in the 1st turn! Unfortunately, I didn't have much time to play a lot with the clickers, oil level and fork pre-load. But the results are not bad, not bad at all. Plushness is definitely improved. The bar doesn't 'vibrate' as much on choppy stuff and the ride is much less tiring. I also have now better control of the front wheel in the turns. It doesn't wash out so easily. I could take tighter inside lines without the front end jumping around and pushing me to the outside. I was also more relax in the breaking bumps or on a rough straight before a jump. Now, I can even feel how the shock works... But bottoming resistance has not been improved. I hope to test the bike again tomorrow on the same track. Now that the fork has more plushness, I can probably increase the pre-load and oil level and see how bottoming/plushness progress. We will see after that about the next valving mod... In the meantime, feel free to share any remarks or ideas. I'll be back soon with more test report. [/QUOTE]
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02 KTM520SX - Playing with valving
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