Appeal to all CRF USD fork and clamp SM convertion!

View previous topic View next topic Go down

Appeal to all CRF USD fork and clamp SM convertion!

Post  sliabhrossa on Mon Feb 06, 2012 9:17 pm

Hello all.

This is my first post, I am Rossa from the south coast of Ireland, a beautiful place with brutal roads in shocking condition, supermoto is the way.

If you have a few minutes i would like to ask your advice on the geometry of my bike, first let me describe it and then let me note what I have done to try to fix my problem. To no avail.
She is an XR650R with the front end off a CRF450R running on 17" excel rims and talon hubs.
Front forks are USD Showa. Clamps are CRF clamps with the XR stem pressed into it.

My problem is a lack in stability or a twitchy weave in the front after 50mph, it can be very unsettling especially upright accelerating hard and at high speeds.

I have:
Replaced front wheel and stem bearings, balanced the wheel vertically and dynamically, tried different fork oil volumes and weights, tried different tyres, dropped the forks in the clamps as low and as high as I could, renewed swinging arm bearings and linkages, balanced the rear wheel an tried different rear tyres. Installed a steering damper or stabiliser in america. All without any improvement.

My thoughts now lie with the clamps. The lads who pressed in the XR stem into the CRF clamps where just lads, engineers offshore in the north sea on an oil rig. Every other component is by an engineering company except for the work they did.
Maybe they pressed it in off plumb or off center. It looks straight.

Do you ever hear stories like this?
I would love to splash out on fancy clamps from Emig Racing, if i thought they would work, but i would be loth to find out the €500 i'm going to spend made no difference.

I could buy an original front end for an XR, 21"wheel and all, for the same money.
Should I go back to an original front end as I am also going to overland again?
I have a 21" CRF front wheel and an 18" XR rear, a big safari tank, nice luggage rack etc.

This is my present predicament.
I cant imagine what else it could be.

It might be you have had experience with this trouble.
Hoping to hear your opinion and advice soon.

Rossa in Ireland.
avatar
sliabhrossa
L Rider

Joined : 2012-02-05

Posts : 2
Location : West Cork, Ireland
XR650R Year : 2000

Back to top Go down

Re: Appeal to all CRF USD fork and clamp SM convertion!

Post  One_Wheel_Jimmy on Fri Feb 17, 2012 8:10 pm

Rossa, recently I had the same problem with my XRR supermoto after doing the CRF fork conversion.

I found the problem to be too much weight on/transferring to the rear tire making the front light and twitchy under hard acceleration. The combination of that and the front fender catching the wind had it floating around like a leaf in the wind.

Lowering the forks 5 mm in the clamps helped a little but what solved the problem was stiffening up the rear shock with a few clicks of compression and moving my butt 10mm forward. Now it pulls all the way to the top of 5th gear with the front glued to the road and cruises at 130kph nice and smooth.

Supermoto is the way!!!!
avatar
One_Wheel_Jimmy
L Rider

Joined : 2012-02-17

Posts : 10

Back to top Go down

Re: Appeal to all CRF USD fork and clamp SM convertion!

Post  sliabhrossa on Tue Feb 21, 2012 12:26 am

Thanks Jimmy.

I have tried dropping the clamps down like you say and stiffening up the rear, to no avail. It seems to be no matter what I adjust there is no difference.

Which leads me to think the problem is in some component. Namely the clamps as they are the only thing not made by an engineering company...

Ill put them on a laithe to see if they spin true.

Thanks again,
Rossa.
avatar
sliabhrossa
L Rider

Joined : 2012-02-05

Posts : 2
Location : West Cork, Ireland
XR650R Year : 2000

Back to top Go down

Re: Appeal to all CRF USD fork and clamp SM convertion!

Post  Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum