1999 Showa Fork on CR250 Tuning?


5 replies to this topic
  • ibergman

Posted June 19, 2012 - 08:52 PM

#1

Hi all,

I've been getting back into dirtbiking after several years off, and just bought myself a 1999 cr250 (07 graphics, don't get confused) after most of a year on a 1990 XR250R. Its fast!

Posted Image


Anyways, the fork is soft through the first 4 inches of travel, but stiffens up immensely after that. I can really only get about 5 usable inches of travel out of it currently.

Does anyone know much about these forks, ie what knob does what? And pulling them apart?

Both sides of the fork have identical:
top of fork, flat-head setscrew = comp. S <----> H
top of fork also, flat head screw that I've been told is an air bleed? does it have a schrader fitting under there?
bottom of fork, flat-head setscrew = T.E.N S<----> H
bottom of fork, castilated 18-ish mm nut, probably holds everything together.

I'd imagine that the sudden ramp-up in fork stiffness is due to too much oil, maybe the fork runs through partial travel but hits the oil and cant compress anymore. I don't think any spring can be so non-linear as to stop travel seemingly 1/3 of the way through. What my best plan-of-action?


Thanks for reading, replies are much appreciated.

-Ian


EDIT: I've already spun all the set-screws to Soft. What does T.E.N. mean (top end .... is my guess) and where the rebound knob?

Edited by ibergman, June 19, 2012 - 08:54 PM.


  • kan3

Posted June 20, 2012 - 07:15 AM

#2

Well, if you think it's an oil volume issue then open the forks up and measure how much oil you have in them.

Stock is around 370cc

  • KTM-Lew

Posted June 20, 2012 - 09:15 AM

#3

The slotted screws on the caps are for compression. They slow how quickly the fork moves on compression. The slotted screws at the bottom are rebound. When the clickers are turned IN they slow the wheel response. Set all clickers to the middle of range.

You will need a wrench that fits the cap. http://pitposse.com/poshfocapwr4.html

Remove the fork tubes, loosen the cap/cartridge assembly and dump some oil into a measuring cup. Remove 40cc and pour rest back in. If it still seems to stiff you need to pull them apart and see what has been done to them.

Make sure the front wheel is installed properly. http://www.moto-pro....k_alignment.pdf

Actually try the axle alignment and retorque the triple clamps first!

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  • shockdoc

Posted June 20, 2012 - 08:05 PM

#4

Your front brake cable is routed wrong......

doc

  • ibergman

Posted June 21, 2012 - 06:52 PM

#5

Your front brake cable is routed wrong......

doc



Why? Do you run it through the bottom of the number plate or something?

And thanks KTM-Lew... I've never heard of axle alignment as an issue. As seen in the picture, is the offet slotted screw (next to the compression screw) an air bleed? Should I let air out before pulling the fork apart?

Posted Image


And how does this inner- and outer-nut setup work? Outer's about a 48 mm and the inner might be 30-ish mm. I've never seen a fork set up like that (I'm used to mountain bikes, and have pulled a couple forks apart, just not moto). Loosen which first?

I plan to pull it apart this weekend.... see how it goes.

Thanks

  • KTM-Lew

Posted June 21, 2012 - 07:26 PM

#6

Brake hose goes in front of number plate.

Loosen top triple clamp bolts then the large hex. Should be 50mm. Pour "some" oil out of each leg. With axle centered, triple clamps torqued properly, reduced oil volume & clickers set to 12 out, try it.

Yes the other screw is a bleeder.





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