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Joined
3/28/2022
Location
GB
Hi anybody got any old shim stack settings for the WP extreme forks as I’m just rebuilding several old KTM’s to race in the UKevo series and I know these forks can be made to work really well but my local tuners don’t have any experience with them so I’m going to try myself. Any help appreciated
My Dad is an expert on these forks. He has rebuilt a ton of them and built some awesome setups with them.
These shim stacks aren't for MX but should work for many outdoor tracks
Other upgrade notes:
This master cylinder is a big improvement
Newer Magura 9.5mm lever / Master Cylinder 2000302
The best suspension upgrade is the Ohlins TTX. If you can find one for a model year around 2008 and lower it 5mm. (The shock length in '99 was 405 mm) You have to grind a bit off the lower shock mount top so the newer models will fit, but it is worth the effort.
The clutch basket and the plastic shift locator are the next things I would look at.
https://www.track93.com/2019/05/clutch-basket-and-inner-hub-replacement…
My Dad, my brother and I all have at least one '99 KTM and they are some awesome bikes.
Also these are the fork seals we have been using:
The fork boots we run are from the KDX 200
The lower chain roller can be replaced by the slide found on 2003 bikes. The MX version is smaller and the one we have been trying out.
Wow thanks CodyC that’s great info. I have 2 1999 already a 125sx and a 200mxc which I have converted to an SX I have already tried an Ohlins TTX on the rear lowered to 405mm but I didn’t like it so I now have a WP Trax which works really well I also have a 2006 rear shock on the 125 and that works well. I have 3 sets of forks now so I have put gold valves in one which didn’t improve them if anything they are not as good as the standard units so that’s why im trying to modify the standard valves hence this post. The engines on both bikes are amazing and I have a rekluse auto clutch ready to go in the 200. I have poured a lot of money into them as they have had a hard life before I got them.
I have already swapped out the chain roller for the slider and had a billet top triple clamp made so I can mount oversize bars and install an hour meter. Cost me a fortune but after racing it for the first time last week I’m really impressed with it. I think the 200 is probably the best 2 stroke motor I have ever raced and I’ve had lots including the latest FI 250/300.
Can I ask why the mid valve rebound assembly is not the same across both forks? Also have you tried adjusting the float on the mid valve compression stack as it’s the fork hold up I’m struggling with, they are super soft at the top of the stroke even with 5.0 springs. The bottoming resistance is great but mine need more hold up and firmer valving at the start of the stroke they ride too low and dive under braking but then get really stiff in the bottom third of the stroke. I believe this is where reducing the float on the mid valve is key but I’m new to trying to valve forks so just trying to get my head around it
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My Dad is saying the following:
Clickers adjust the low speed and don't affect the high speed as much. I try to tune the High speed Reb on the comp side, and the Low Reb on the Reb side. There are a lot of older forks that seem to have stacks like this.
The mid valves in these forks only do Reb, there is just the check valve. If you are talking about the float of this check valve, I have not tried changing it. I have seen some riders experiment with a mid that does compression and reb.
For the top travel, check your spring preload, (which I'm sure you have) I have also had some success running 15w oil in these forks. They felt good up top, but bottom was a bit harsh.
Check the Cst of your oil, these forks have small valves and IMO you can really tell a big difference.
No problem and glad to see more people riding these bikes, I hope your race goes well!
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