An Unholy Union II: Wp Extreme 50mm Conventionals on a G/S

[hardwaregrrl]

I just rode up to Detroit to visit family. I have noticeable pogoing on asphalt around 30mph. And I am just getting way too much feedback from the forks. Might have to bump up the oil cc's. It's pretty solid on fast gravel I can feel the plowIng effect in the turns much more. I'm running comp about 20 + and rebound 10-

[ontic]

Great to see you both getting some running time on these forks.

Might be time to start trying some different (heavier) fork oil weights?
Who's got what in there? 5W in both is it?

Playing with oil weight rather than valving is what Paul Rooney recommended.
What I'd really like to know is if our different forks from different model KTM's had different shim stacks. Seems logical that they would to me.

I've emailed Neil (the guy who with his girlfriend is about to ride two of Pauls WP50-fronted steeds around the world) to ask what oil weights they are running.

Also, Jenna,
did you ever take the tops off your spare forks and see how those adjuster knobs have been done?

[hardwaregrrl]

I took the forks apart but haven't made a tool to seperate the rods yet. I know, I'm lame. I might bump up my oil amount. I think im running ten weight? Of course he didn't write it down

[SOLO LOBO]

Originally Posted by hardwaregrrl

I just rode up to Detroit to visit family. I have noticeable pogoing on asphalt around 30mph. And I am just getting way too much feedback from the forks. Might have to bump up the oil cc's. It's pretty solid on fast gravel I can feel the plowIng effect in the turns much more. I'm running comp about 20 + and rebound 10-

I think the pogoing means you don't have enough comp and rebound, or the springs aren't the correct rate

Have you calculated your sag to see if the springs are giving the right laden sag? If they are too stiff they could be the cause as well

I would say to start with checking your sag

I can't remember the oil weight I used (and will check) but think the volume was something crazy like 800cc per leg

[SOLO LOBO]

Originally Posted by SOLO LOBO

OK, the KTM fork tubes, each with 800cc of 5wt oil.

There you have it!

But as I am running 5wt, and have alll 24 clicks of comp dialed down I think that is a real indication the valving needs to be addressed.

My forks were originally from a 640 Adventure, so if the valving is model specific, these forks should have the closest to what we need.

Jenna, I think you springs are 64's, I don't have any pogo'ing, but supple travel throughout the range. If you sag isn't close to that 30% target your springs may be too stiff.

But, you can always crank up the rebound and comp and see if that makes it better

[ontic]

Solo, I'm usually looking for the complicated solution, but don't blame your valving just yet mate, try some different oil weights and maybe volumes (or heights from the top more specifically). 5W is pretty damn light.
I still haven't heard back from Mr Rooney or Neil (the guy with two WP50 Rooney bikes) about fork oil weight but I think I recall the numbers 10w (comp) and 15w (reb) as working well. If I get some news on that I will correct myself.
As it happens I'll be planning on meeting Mr Rooney sometime in the next couple of weeks (heading up North in two days).


there is also this post about the subject I found a while ago.

Moto520's WP Extreme Settings


Ive had allot of experiance with the wp 50 mm forks. I also weigh in the 200lbs range .
I race vet A mx at RED BUD and some pretty awsome tracks around here, also GP's and scrambles. Over the years I have found that they work best, for me anyway, with the following. First when installing seals use a bullet tool or cut the corner off a plastic grocery bag and slip it over the tube to act like a bullet tool. gotta save fron the sharp edge. Remove the seal springs and unscrew where they connect. Cut 5-8 mm off the female end and reconnect. Install them . Do the same on the wipers . This greatly reduces the weeping.
If they do leak use three wrapsmasking tape around the tube with an outward slash cut, work in into the seals rotating so the dirt rolls up along the slashed edge effectively removing the dirt that makes them leak.

.44 spring at 10 mm preload, 130 mm oil level with 10 weight in the compresiion side and 15 wt in the rebound.

I use a Torco oil as its very ressistant to foaming compared to , Maxima , spectro, silkoleen, defintely stay away from Belray. The 50's have such a large bottom out cone they can be plush initially and still offer up a great bottom out action. Flex will be better than the biggest inverted fork using a Summers fork brace. I can back my comp and rebound off and go crazy in the woods or turn um in and mx as if two different forks were on the bike.

The range of adjustability is awsome with these just by spring rates and oils weights and volume. No inverted fork will match a conventional forks action for overall performance.The 4 stroke ktm with these forks on them is just unbelievable. Straddle your 48 or 43 mm forks clamping with your legs and holding the bars with the front brake lever compressed . Move the fork lft to right and see how much they move . Try that on a 50 mm fork with and without a Brace. The brace makes the difference and now the fork is clamped in four places. The little bit of flex the fork may have at the bottom t clamp when riding isnt a noticable amount and may be of some benefit. The 50 mm forks usually dont need much in the way of stack valving for most riders.

about Jenna's pogoing. I don't know the ins and outs of suspension problem analysis but I'll put my money on oil weights as well for now too. Probably not the complete problem, (like you say, check that sag, etc). Despite my .6's feeling stiff out of the bike, in the bike they feel pretty damn soft and plush to me. I doubt Jennas .65's would be that alarmingly wrong.
When my rear shock on the G/S was obviously failing- leaking and completely worn out- it was not damping properly. Cruising along at 60-80kmh had me constantly bouncing along with natural road bumps and undulations. Pogoing would have been a good word for that as to me it just sounds like un-dampened spring action.

[Stagehand]

I was trying to think of the right words, too, but i think you nailed it. Pogo-ing would be undamped action. Needs more damping probably both on compression and rebound. Probably mostly rebound, but that where it gets fuzzier.

[SOLO LOBO]

Guess I need to by some 10wt and 15 wt to test out...

[hardwaregrrl]

I really wish I would've taken on the challenge of setting the forks up myself. I feel a bit gipped. I'm in Detroit right now and am leaving in the morning. Ive had the wheel on and off the bike maybe 2 times since the cOnversion and I have a stripped thread on one of my pinch bolts. And another is on its way out. I'm not sure how you would repair a pinch bOlt thread. Some serious soft aluminum.

[SOLO LOBO]

Originally Posted by hardwaregrrl

I really wish I would've taken on the challenge of setting the forks up myself. I feel a bit gipped. I'm in Detroit right now and am leaving in the morning. Ive had the wheel on and off the bike maybe 2 times since the cOnversion and I have a stripped thread on one of my pinch bolts. And another is on its way out. I'm not sure how you would repair a pinch bOlt thread. Some serious soft aluminum.

Helicoil and a bottom tap is the easy way...a timesert is a bit stronger and not harder.... the kits run about $65, but includes the tools.

If you let me know the size (thread pitch as well) I can check my kits and loan it to you (all you leave in the fork is the insert).

[hardwaregrrl]

I guess I don't get how you get the sert thru to the back. You don't want to drill the front hole any larger? I think it's an 8 x 1.5

[SOLO LOBO]

Originally Posted by hardwaregrrl

I guess I don't get how you get the sert thru to the back. You don't want to drill the front hole any larger? I think it's an 8 x 1.5

OK, I forgot about the layout for the pinch bolts... this will rule out the timeserts leaving you with heliciols.

You will have to drill both holes larger, but that shouldn't matter as you can use a washer under a slightly longer pinch bolt to apply the needed clamping force.

The only other options would be to use a slightly larger bolt and try threading it into the existing hole, or welding up the hole and re-tapping to the OEM OD

[SOLO LOBO]

laden Sag:

So with the stock 640 springs I had 37% laden sag (post #297

With the 0.60 rate Slaven springs this changed to 21% (post 305)

With my new Konflict springs at a 0.54 rate I have 24%

So, I'll assume the springs are fine and will move to a different weight oil.

I happen to have a bunch of 10wt (enough for one side) and will get some 15wt for the other this weekend.

[ontic]

Good luck Solo, looking forward to some more feedback,
and thanks for the heads up about the pinch bolts Jenna. I'll try to restrain my gorilla hands when doing them up in the future. I hope you manage to fix that with not too much suffering.

[SOLO LOBO]

Jenna,

How is the lever travel on your front brake (assuming you have the BMW master cylinder and KTM caliper)??

I am using a little less than 50% of the lever travel to get the brakes fully on and have bled the caliper three times now with little improvement.

I actually just ran out of brake fuild and need to go get more... I've tried the caliper at a number of difference angles (while bleeding with my mitimite) as well and banging the caliper, line and master cylinder wth a rubber mallet.

Think I will go clean and grease the caliper sliding pins since I don't have any brake fluid...