Posts
112
Joined
11/20/2013
Location
AU
Edited Date/Time
2/26/2019 4:26pm
Hi everyone,
Thanks Slipdog with help before on this.
I thought I bought 505mm springs for my 06 Open Chamber WP's but after taking the forks off the bike and doing it properly, they're actually 495mm. I think they're for a later model fork. For this era WP, the manual states stock full length (spring + spacers) = 523mm, 5mm preload.
Stock springs were 505mm + 15mm worth of preload spacers. (520mm).
New springs are 495mm + 15mm stock preload spacers + new 10mm preload spacers. This is back to the stock length.
When I measure fork preload now, ie, spring bottomed out but no fork cap installed, I'm getting 272mm. When I screw the fork cap back on and mount it up, I get 258mm.
Thats a 14mm preload gap - 9mm higher than recommended 5mm preload - is this ok as I've 'spaced' the spring 10mm?
If I take out the new 10mm WP preload spacer I bought yesterday, it would bring the theoretical preload back to spec, but be 10mm lower than recommended total spring length.
Any help is most appreciated.
Cheers!
Thanks Slipdog with help before on this.
I thought I bought 505mm springs for my 06 Open Chamber WP's but after taking the forks off the bike and doing it properly, they're actually 495mm. I think they're for a later model fork. For this era WP, the manual states stock full length (spring + spacers) = 523mm, 5mm preload.
Stock springs were 505mm + 15mm worth of preload spacers. (520mm).
New springs are 495mm + 15mm stock preload spacers + new 10mm preload spacers. This is back to the stock length.
When I measure fork preload now, ie, spring bottomed out but no fork cap installed, I'm getting 272mm. When I screw the fork cap back on and mount it up, I get 258mm.
Thats a 14mm preload gap - 9mm higher than recommended 5mm preload - is this ok as I've 'spaced' the spring 10mm?
If I take out the new 10mm WP preload spacer I bought yesterday, it would bring the theoretical preload back to spec, but be 10mm lower than recommended total spring length.
Any help is most appreciated.
Cheers!
Things to consider are that WP most likely set it up originally it up with all that preload to compensate for the fact they used a spring rate better suited for a 125. You have gone up 6 spring rates for your weight, the stiffer the spring rate, all things being equal, the less the preload you need to get the sag/ ride height correct.
If you have a shock spring 6 sizes too soft you'd need a massive amount od preload to get your race sag in the 100-105mm range. If you go up 6 rates and leave the preload the same your race sag would be under 90mm and the bike would ride stinkbugged and handle terribly. Forks work the same. If you run 14mm preload with .47kg fork springs they will be very harsh on the small chop and will not want to turn at all.
Also, those are not the first set of Q springs I've come across that were the wrong length but never by that far. 43mm X 495mm are 47mm showa fork spring specs.
Man. Thankyou. You are a bloody legend.
I've dropped out fork oil and will grab new 5w Motorex Fork Oil and fill to 110mm oil/air gap tonight, and load the preload spacers back in as you state.
Thanks so much, for the explanation and the help. Do you do this for a living?
Pretty nuts KTM spec'd the 06 300 EXC (Heaviest 2 stroke bike they made in 2006) with softer springs than the 06 125SX (4.0 vs 4.2). If anyone even thought about taking their 300 EXC to a jumpy track for a day, they'd have no hope - like me last time at Mt Kembla MX near Wollongong, NSW, Australia.
My YZ125 was so nice to ride, floating over everything, but the old 300 felt like a sinking ship. KTM must have presumed anyone buying a 300 would be strictly cruising in the bush only!
I read a bit about springs before I bought these, and heard that Q-Springs were pretty decent. Can't really say I'd recommend them after this!
Thanks for all the help mate.
Just for reference here's a link to Slaven's Racing showing the spec'd 505 spring for your bike and also recommends the 4.4N for your weight instead of a 4.6N like we discussed in your other thread.
https://slavensracing.com/shop/fork-springs-wp48mm-43mm-x-505mm-ktm-hus…
Cheers!
That explains it! 16 years ago I was just starting high school so I'm sure you've got it pretty sorted by now. Do you run a suspension shop in the USA?
Your memory is correct, unfortunately the EXC didn't get the SX style preload adjuster, its just the black rebound adjuster on this off road fork. The manual states exactly what you are referring to with the SX models however. Thats pretty cool the SX forks had that feature.. WP's seemed to have such a bad rep back in those days.
Thankyou for the link! Great Chart - looks like perhaps 4.4's would be better for me... let's see how next weekend goes with these heavier springs. Jeff's chart does say the 4.2's were stock on this model, but mine had the 4.0's inside (well, according to the KTM manual anyway). The bike has Cycra handguards, KTM bashplate, FMF Fatty, heavy duty tubes, and soon an IMS oversize tank, so maybe the extra weight onboard will counter the heavier spring.
The Shop
If your forks feel a little firm but not too terrible you could always lower the oil level to like 125-130mm to trick it into feeling a bit softer.
So...do you ride the NorCal tracks? How are things looking up there?
Used to get to E-Street and MMX all the time but haven't been in ages.
I have yet to get to Diablo but have heard nothing but good things about it.
Thanks so much for your help Slipdog with those particular fork setting details - fork felt great, hitting 4th gear jumps on the 300 now is so much nicer, no more tire marks under the front fender.
Cheers mate!
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