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Old 11-18-2010, 09:18 AM   #196
CrazyIvan
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Here's my missus' bike with 43mm wp's in it.



Before she tried:

48mm Super Enduro forks with clamps, she didn't like the turning circle...
My HP2 forks with the lower legs of the XC, no big improvement...

We ended up using 43mm WP forks (Husaberg), so we could keep the original triple clamps.

All you need to fabricate is the axle, the left axle clamp diameter is 1mm smaller. (You could machine the fork leg to fit the original axle).

To mount the brake caliper I used the brake caliper adapter of a KTM 950 SE.
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Old 11-18-2010, 10:28 AM   #197
magno
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Wheels

While we're in that area, what about wheels? I know that Colebatch replaced his front with an Excel A60 (expensive)

Some people I have spoken to seem to think that rebuilding the existing rim with heavy duty stainless spokes will strengthen the wheel and stop the problem of being unable to tighten the spokes once the ally ones have loosened off. (Much cheaper than the Excel option).

What d'ya all think about that?
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Old 11-18-2010, 10:38 AM   #198
MTBiker78
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Quote:
Originally Posted by magno
While we're in that area, what about wheels? I know that Colebatch replaced his front with an Excel A60 (expensive)

Some people I have spoken to seem to think that rebuilding the existing rim with heavy duty stainless spokes will strengthen the wheel and stop the problem of being unable to tighten the spokes once the ally ones have loosened off. (Much cheaper than the Excel option).

What d'ya all think about that?
you can always try to use excel takasago rim (better than stock one and cheper that profi A60) and standard hub and spokes. ;)
no problems since I did that ... 17000km in mostly offroad.
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Old 11-18-2010, 12:49 PM   #199
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Quote:
Originally Posted by Colebatch
I didnt answer because I dont know the answer .... But if you need answers from people who dont know, then I will throw something out there. No guarantees. Thats my disclaimer

I dont know much about WP forks apart from the 48mm ones. So the WP forks you have have 54mm upper clamp diameter and 57mm lower? Sounds like 43mm forks ... I think thats the sizes of the old WP 43mm forks.

If yes, thats a third of the fitting issues sorted. The forks fit the bike.

You also have to figure out how to make the forks attach to the wheel. You wont be able to use the BMW axle clamps ... which screw onto 45mm tubes. So thats a problem.

Then you have to figure out how to make the brake disc and caliper fit the forks and wheel. This is the biggest problem.

I think the reason you got no responses is that no-one has tried using those forks on this bike - so no-one knows 100% what you are going to have to do to make it work. You should have a talk to LukasM ... he is lord of WP forks and fork fittings and brackets and will know what is possible.

Sounds like a major job to work out how to attach the wheel and brakes to me. You might be able to use your KTM axle clamps, wheel, and brakes, but you probably have to get a custom axle and spacers made up. The BMW and KTM triple clamps have the forks spaced differently, so your KTM axle and spacers will be too short to use with the BMW triple clamps. As soon as you change the wheel spacers, you will then have to custom make a caliper mount. Because the caliper will be too far away from the centre of the wheel with wider BMW triple clamps.

You should also check the offset of the KTM axle clamps, compared with the BMW offset. You dont want much difference there.

Can you confirm the exact upper clamp size on your forks in mm (54?), the lower clamp size in mm (57?), and slider tube size, in mm? (43?)
Thanks for that, I'm trying to research the topic before committing to spend the money so any answer helps clarifying.

the clamps are 54mm top, 57mm lower, didn't measure slider tube. The bike I measured it from its a 2002 ktm 300 exc.
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Old 11-18-2010, 12:55 PM   #200
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Quote:
Originally Posted by LukasM
If they are 54mm on top and 57mm on the bottom they will be 4357MXMA forks aka 43mm USDs. They should have a 20mm axle and 95mm caliper bolt spacing, so the same as the later WPs. Obviously not as plush or strong as the newer stuff but they can be made to work pretty good.
It sounds like they're those.

I was looking to avoid replace the triple clamps, which may be expensive and have other minor side effects. It seems not being able to use fork legs will also be interesting excersise at least or require change wheel etc, which would also make it expensive.

Thanks for your answers
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Old 11-18-2010, 02:06 PM   #201
The Jester
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Quote:
Originally Posted by CrazyIvan
Here's my missus' bike with 43mm wp's in it.



Before she tried:

48mm Super Enduro forks with clamps, she didn't like the turning circle...
My HP2 forks with the lower legs of the XC, no big improvement...

We ended up using 43mm WP forks (Husaberg), so we could keep the original triple clamps.

All you need to fabricate is the axle, the left axle clamp diameter is 1mm smaller. (You could machine the fork leg to fit the original axle).

To mount the brake caliper I used the brake caliper adapter of a KTM 950 SE.
By fabricate an axle do you mean you need to make a new one or machine the existing one? Any details would be appreciated. Is this just a case of machining down the the end of the original axle in a lathe? Does this affect the threaded part of the axle?

How do these forks perform compared to stock / replacement 45mm marzzochis?
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Old 11-19-2010, 03:16 AM   #202
Dukehunt
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Well that's it, WP front end conversion is now complete, short ride on tar and a few footpath (sidewalk) excursions and all feels good so far.
Might need to beef up the front springs even more as there is a fair amount of sag with the Touratech tank half full.
It does turn better on the tar, feels more agile but will get more feedback tomorrow, try and hit the local bush tracks to get a feel for the difference
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Old 11-19-2010, 02:22 PM   #203
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"PS guys, dont get confused between HP2 the motorcycle (crap forks) and HP2 the name of an ADVrider who did a successful marzocchi shiver transplant (good forks) onto his Xchallenge"

Hi Colebatch,
What you write is as always 100% correct, I like that.
The fork of the HP2 and the x Challenge looks just the same.
Inside they are totally different.

I build a "real" Marzocchi Factory Shiver for my XChallenge with a 4 Piston Brake and a 330mm Disk

And i build a real, very good Marzocchi Fork for my HP2 with a
Radial Brake Zylinder, and nice Fork Clamp.

You now who build Fork Clamp for the X?
Emig make it only for the Top?




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Old 11-19-2010, 02:27 PM   #204
HP2
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And the Last.

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Old 11-19-2010, 08:01 PM   #205
Dukehunt
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WP48 front end on the XC, why did I wait so long to do this, even under-sprung it is light years ahead of the old forks.

On tar feels pretty much the same but turns easier , less input.
On dirt, I only had a chance to do some easy stuff as I was on my own it was great.
The ground was severely rain rutted, many muddy puddles, lots of woops and it felt just great so far, tracked very true, felt stable in rocky areas, that harsh small, not reactive quick enough feeling has gone, that feeling of front end washing out in the loose stuff has gone, so far it feels like a KTM.

Will get a chance next weekend to do some higher speed stuff, maybe not as challenging but can't wait to try some more difficult terrain.

A big thumbs up

One thing I might do is use a 310mm or 320mm front disk, the standard KTM rotor feels a bit weak

To those who want to make the change, go for it.
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Old 11-20-2010, 03:12 AM   #206
Colebatch
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Quote:
Originally Posted by HP2
And the Last.

Love your work :)

What caliper / disc is this from?
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Old 11-20-2010, 03:25 AM   #207
Colebatch
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Quote:
Originally Posted by pampaX
It sounds like they're those.

I was looking to avoid replace the triple clamps, which may be expensive and have other minor side effects. It seems not being able to use fork legs will also be interesting excersise at least or require change wheel etc, which would also make it expensive.

Thanks for your answers
replacing the triple clamps may not be that expensive ... if you use the whole set up from your EXC ... use the forks, wheel, brakes, triple clamps ... then the only thing you need to do is work out how to mate your KTM triple clamps with the BMW frame. I think thats easier and simpler than custom making a bunch of other stuff.

Maybe you need to get a new steering stem made up ... or maybe you can machine the KTM one. One of those two options should be all you need to make it work if you transplant the whole front end from the KTM, wheels brakes, forks and triples.

You will have a smaller turning circle ... because the KTM forks will be closer together and will interfere with the BMW frame earlier than the wider spaced BMW triple clamps, and you will have to solve your own issues about where to mount the ignition switch and instruments, but apart from that, it should work.
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Old 11-20-2010, 03:42 AM   #208
Colebatch
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Since I dont have pic of my front end on this thread:

This is the X with WP 4860s .... from a 640 Adventure R.

With:
KTM triples (machined KTM stem to fit 28mm BMW bearing size)
990 brake disc
30mm axle clamps / axle
950/990 spec Haan Hub with Excel A60 rim

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Colebatch screwed with this post 11-20-2010 at 06:24 AM
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Old 11-20-2010, 04:39 PM   #209
muddyrabbit
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So anybody in here interested in selling off their stock front X Challenge forks to one of us mentaly handicapped X Country owners? I figure with all of you looking to replace them this would be the place to ask.
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Old 11-20-2010, 07:52 PM   #210
dirtsurfer
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Quote:
Originally Posted by muddyrabbit
So anybody in here interested in selling off their stock front X Challenge forks to one of us mentaly handicapped X Country owners? I figure with all of you looking to replace them this would be the place to ask.
These have been on ebay for a while now he's asking for offers
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