BMW G650XChallenge FRONT SUSPENSION

[Deco]

Originally Posted by Max Kool

Not sure if a steering stabilizer will help you. Most headshakes that I know of are "low speed" oscillations (low speed as in "quite slow left to right movement", 1 Hz or even lower, with a low amplitude). You need to tighten up the steering damper quite some to ease these. Steering stabilizers are mostly efficient in damping high speed shakes from ruts and rocks that would normally shake the bars out of your hands.

I know from first hand that the Xchallenge is quite susceptible to tire choice. On Michelin Enduro III and IV this bike behaves very bad at higher speeds on tarmac at any speed over 65 mph. On Michelin Baja this bike is much better.

Consider different tires first before you invest in a steering damper, otherwise you might end up with a bike that is stable, but will hardly go round tight corners imho, or otherwise is excellent in thed desert but still shakes its head.

(don't get me wrong, I'm not against steering dampers, I'm just doubting if it's the most efficient way to solve your particular problem)

Great info Max. You are so right about the bike and the tires. The X is very finicky as to what off road oriented tire you use when it comes to tarmac. On dirt there seems to be no problems. It seems several guys are running D606s and have had similar problems when running at higher speeds on pavement; i.e. getting to/from the trail. The dampers appear to help. I had D606s and experienced the same problem Now I have Michelin Deserts and the problem is worse. The Emig should help and also allow me to upgrade the front end to KTM down the line.

BTW I emailed Erik from his web page about an X-tank but have not heard back. Do you know if he is still selling them?

[LukasM]

If you guys are having problems with stability and you are considering a WP fork swap anyway, I would simply use the much cheaper KTM triple clamps. These have 20mm offset vs. the stock 25mm, and can be adapted to the X-Challenge quite easily. Colebatch has done it and is happy with them (and D K will soon ), check his build thread for details.

[Colebatch]

Originally Posted by Dukehunt

About to start the WP conversion to XC

KTM Front wheel (in transit)
EMIG racing conversion kit (in transit)
KTM Disk rotor
04 KTM WP forks, re-sprung with stiffer springs, new 5w oil and seals (need to test)
KTM Front Brake Caliper (hopefully the XC brake lines and master Cylinder will be adequate)

Go to go to the Moto GP at Phillip Island so I will start when I return later in October

Any know if any thing in particular to lookout for ?

I didnt need a different caliper. KTM and BMW both usually use the same brembo calipers. Lukas can explain better, but it is just a KTM caliper bracket with 75mm pin spacings that you need. The XC caliper slides on that and fits the KTM brake disc (assuming its 300mm) on KTM compatible front wheel just fine. So obviously if the caliper is the same, the brake line and master cylinder are the same too.

[Colebatch]

Originally Posted by Deco

BTW I emailed Erik from his web page about an X-tank but have not heard back. Do you know if he is still selling them?

He is still selling them. He might have missed it ... try him again ... erik@hotrodwelding.nl

[LukasM]

Originally Posted by Colebatch

I didnt need a different caliper. KTM and BMW both usually use the same brembo calipers. Lukas can explain better, but it is just a KTM caliper bracket with 75mm pin spacings that you need. The XC caliper slides on that and fits the KTM brake disc (assuming its 300mm) on KTM compatible front wheel just fine. So obviously if the caliper is the same, the brake line and master cylinder are the same too.

Yeah, just be careful to get the right bracket. The single cylinders models have a caliper with different spacing than the twins, but the mounting at the axle clamps is the same 95mm distance for most KTMs (other than SM and SMR models). By using the bracket and the matching 300mm disc from a KTM 950/990 Adv on Walters bike, he was able to retain the rest of the stock brake components.

[pampaX]

Hi, I'm considering putting different forks but I'm very technically limited .

Can someone detail which WP forks would be suitable?
i.e i'v seen 640 ones on web and also some hussaberg ones at reasonable $.

Another question, I measured the diameter of the forks on my ktm 300 '02 and they seem to fit the clamps of x-ch ... does this mean that size of 640/950 is different? Why do I need different clamps?

What about the wheels? I understand by reading the posts that I need a ktm hub.

I appreciate some help and sorry for so many questions.

thanks,
PampaX

[Cruz]

Originally Posted by Deco

Great info Max. You are so right about the bike and the tires. The X is very finicky as to what off road oriented tire you use when it comes to tarmac. On dirt there seems to be no problems. It seems several guys are running D606s and have had similar problems when running at higher speeds on pavement; i.e. getting to/from the trail. The dampers appear to help. I had D606s and experienced the same problem Now I have Michelin Deserts and the problem is worse. The Emig should help and also allow me to upgrade the front end to KTM down the line.

BTW I emailed Erik from his web page about an X-tank but have not heard back. Do you know if he is still selling them?

Mine had the head shakes stock standard with the Saharas on and then not quite so bad with 606 front and back after lowering the air pressures. The front seemed to be the big change with lower air pressure lessening the head shake at speed.

After changing to a Michelin Desert on the front and still a 606 on the rear I do not have a headshake at all anymore. I have changed the fork springs to my weight and also the fork oil to correct levels and 10 weight. My left fork tube had less than half the amount of fork oil in it that it should have had, though it has never shown any sign of leakage. The fork springs and oil height made a big difference to how the bike rides, especially on road.

To those fitting steering dampers, would it not be better to solve the problem where it is caused than try to use a damper to mask over the problem to some degree?

Would the problem cause premature wear to other areas of the bike and the steering damper over time?

The cost of a damper could buy a lot of fork work to fix any problems and maybe not need a damper at all. I previously nearly bought a steering damper a few times to try and fix the head shake as mentioned above, but I am very happy to have the fix done properly and now do not feel a need for a steering damper at all.

[FinnDuro]

Originally Posted by Cruz

To those fitting steering dampers, would it not be better to solve the problem where it is caused than try to use a damper to mask over the problem to some degree?

+ 1.

Xchallenge is IMHO a pretty darn stable unit to ride, it is not prone to 'head shake' as standard. Check you rear shock settings, maybe let it sit a bit lower on the back, and change your tyres first, as suggested. Damper is an overkill solution for this only.

[dirtsurfer]

would these be about the right size?

[komatias]

The Supermoto forks will fit. Be careful though. The triple clamps are wider than the enduro ones so they can fit the larger calipers.

Supermoto forks generally come with a radial caliper bracket, shorter stroke, stiffer springs and god knows what valving.

[Colebatch]

Originally Posted by FinnDuro

+ 1.

Xchallenge is IMHO a pretty darn stable unit to ride, it is not prone to 'head shake' as standard.

+2

[Max Kool]

+3

for the stuff a steering damper is meant for, the XC is pretty stable from itself.

If you have a wiggle, it's most prolly tyre setup or too much air in the shock.

[Dukehunt]

Hi Guys,

Thanks for all the info, I am starting the swap out this week and so far have disassembled the front end.
Need to go to the local bearing supplier and get some new steering head bearings to install, I am going to assume that the OEM parts are very pricey.
Hopefully I will finish next weekend and be able to take it for a test run.

[Dukehunt]

Hi Guys,


This washer Part No 31427696734 WASHER - 28,2X44 fits between the the lower ring and the lower bearing, None at any of the local BMW dealers here in NSW so needs to come from the Fatherland, would any one know the thickness as I might be able to source or make one locally.

[Cruz]

Thanks to Az-Twin for his help, these arrived last week.


Will be a couple of weeks before the suspension shop can get to work on them and put the cartridges into the OEM forks as they are moving shop.

Have to make the bottom of the OEM forks look like this.


Hopefully all will go well and they will make a decent front end for the bike.