Fork disassembly - spring/oil change; emulator install

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Simon
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Fork disassembly - spring/oil change; emulator install

Postby Simon » Mon Apr 05, 2010 6:07 am

I won't detail everything, as the Kawasaki service manual and other guides (Lumpia and GeoffC) covers this, but will add some personal observations. Also see other threads on Race Tech Emulators.
Images at the bottom.


Special tools needed:
14 mm hex socket for axle - simple hex key will work, but will lack possibility for proper torquing. (Opposite end of the spark plug tool from the kit is 14 mm as well, but it's rather poor)

Break loose all necessary bolts before raising the front:
Yoke clamp bolts. Fork top plugs.
Caliper bolts. Axle clamp bolt. Front axle.

Remove fender.
Remove calipers. First press both calipers simultaneously toward the brake rotors: You may be able to squeeze the pistons back into the calipers, which will give you more room when it's time to refit calipers around the rotors. Suspend the calipers, don't let them hang by the brake lines.
Loosen axle clamp bolt and remove front wheel.

Now try to remove the fork bottom bolts (beware oil will run out if successful)... This may be tricky as bolts are to be installed using thread lock, and threads into the damper rods, that tends to turn with the bolts. Known suggestions includes: Using an impact wrench. And/or removing the bolt while the fork leg is assembled, and the spring thus pinning the damper rod somewhat. In my case the bike was sitting in the garage at near-freezing temperatures. - Don't have an impact wrench and couldn't break the bottom bolt loose, so I removed both fork legs, emptied out the oil, refit the springs and thoroughly warmed the legs on the living room radiators - then the bolts let go..!
Note: The bottom bolts has washers under them. As they might be somewhat stuck in the recess they are easily missed, so don’t loose them...
The manual specifies these washers should be replaced, I didn't but annealed them best I could with a minitorch.

Loosen the remaining yoke clamp bolts - beware fork leg will drop! - and remove leg. - If you have too little ground clearance, remove the handlebar to be able to open and collapse the fork leg while removing; careful not to bend the brake line...
Remove top plugs - beware some preload is present - and empty out oil, spacer tubes, washers, fork springs, damper rods and top out springs; note that order.
According to the manual there should be a "cylinder base" at the bottom of the damper rods -- I didn't see any...

Each damper rod has four compression holes at the bottom: Enlarge these to 8 mm (5/16") and add another two for a total of six holes; deburr the edges. - Do not modify the rebound holes at the top. Temporarily assemble the fork legs (don't forget the top out springs) and reinstall the bottom bolts into the damper rods; use non-permanent thread lock.
Set the desired preload on the emulator springs - from two to four turns from relaxed is the standard recommendations from RaceTech. Remember to tighten the lock nut against the emulator base when preload has been set.

Now is the time to add fork oil and set the oil level. Remove spacer and spring from fork leg again, add fork oil and pump the leg to remove any trapped air. Use a ruler, or syringe+tube to draw off oil to desired level. This is done with the leg in vertical position and compressed, and the emulator in place on top of the damper rod (as the emulator will take up a volume and therefore raise the oil level. Spring and spacer tube must not be installed.) Oil level recommendations are around 130-140 mm below fork tube edge. Higher levels will give a stiffer fork at the end of its travel. 5 cc of oil corresponds to approx. 5 mm of oil level - in case you want to adjust the oil level later on.

Install fork legs and wheel; grease the axle. To get best alignment keep the fork fully compressed by supporting or tying up the wheel. The top edge of the fork inner tube should be flush with the surface of the yoke (some recommendations exists for 10 mm above the yoke surface). Tighten the axle a fair bit, then the four bottom yoke bolts alternately to their specified torque.
Upper yoke clamp bolt should only be semi-tightened at first: Then install the fork spring, washer, spacer and top plug (to avoid binding of this).
Here's your chance to adjust preload of fork. You may have replaced the springs, cut the spacer tubes shorter or similar; between the spacer tube and the top plug 36-37 mm diameter washers can be added as required to achieve desired sag. (See Sportrider and Wiki)
The manual specifies replacing the plug O-rings; didn't really see the need for that...
Finally fully torque down the top plugs, upper yoke bolts, axle and the clamp bolt.

Measure the distance from the dust seal to the bottom yoke while fork is unloaded and fully extended; this will come in handy later when you want to measure/set the sag; the actual travel of the fork etc.

Reinstall calipers and fender. Pump the front brake until it's firm :mrgreen:

Image Emptying fork legs.

Image Damper rods - before and after.

Image . Image . Image Emulator: Left - this disc lifts when front wheel takes bigger hits (high speed), at slow speed compression the oil only flows through the small hole in the disc. Middle - on rebound this one-way valve allows oil through. Right - valve sitting on top of the damper rod.

Image . Image A syringe with a piece of tube can be used to draw off fork oil to the desired level

Image Washers can be added between spacer tube and top plug to adjust fork preload.

Image Most important part of the upgrade! :think:
Image
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biketechted
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Re: Fork disassembly - spring/oil change; emulator install

Postby biketechted » Mon Apr 05, 2010 9:27 am

Excellent write up! :cool
I'll return later with some questions.
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Addohm
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Re: Fork disassembly - spring/oil change; emulator install

Postby Addohm » Mon Apr 05, 2010 2:45 pm

You might want to mention why you modified your damper rods!

Otherwise, it is an absolutely fantastic write up. :)
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coop
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Re: Fork disassembly - spring/oil change; emulator install

Postby coop » Mon Apr 05, 2010 2:57 pm

nice write up simon. im fighting the damper rod bolts right now
07 650r: Bruce Fab slip on, Race Tech GVE/Springs, BRP clutch springs, -1 front sprocket, BRP air box mod, Sport Bars 2.0, DIY fender elim. DIY CBR 600rr rearsets
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biketechted
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Re: Fork disassembly - spring/oil change; emulator install

Postby biketechted » Mon Apr 05, 2010 8:14 pm

Addohm wrote:You might want to mention why you modified your damper rods!

Otherwise, it is an absolutely fantastic write up. :)


It's in the instructions.
It allows the oil to flow freely to the GVE's and essentially bypass any other potential dampening that the small holes may provide.
I recently went with a kit that doesn't require drilling more holes, but have found I wish to have more damping options. The emulators provide the most amount of tuning without going with full cartridge kits, I believe
I'm going to install the GVE's with stiffer springs in the near future.
djrussell
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Re: Fork disassembly - spring/oil change; emulator install

Postby djrussell » Tue Apr 06, 2010 9:21 am

what kit did you install, biketechted?
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biketechted
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Re: Fork disassembly - spring/oil change; emulator install

Postby biketechted » Tue Apr 06, 2010 12:44 pm

It's a Matris fork kit. :roll:
Includes springs, oil flow regulator (pops into the top of the damper rods controlling oil flow) as well as preload caps.
I'm not a big fan because of the lack of fine tuning. The only way to change damping is to change oil visc. and height.
I'm going to install the GVE's and try to use the preload caps that came with my Matris kit.
Other than that it's a great improvement over stock.
Still, money better spent is on GVE's and springs through BRP.
I like to sometimes be the test dummy on stuff and in this case I wanted to see how well this would work.
I just didn't really want to drill holes if I didn't have to.
Had I not bought an Ohlins rear shock and stuck to the OEM shock, then it may not have been such a big deal. However, with the rebound and compression control available on the shock it made me want more from the fork. :fool

Simon, what length did you cut your spring spacers to? How much do you weigh?
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Simon
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Re: Fork disassembly - spring/oil change; emulator install

Postby Simon » Wed Apr 07, 2010 3:09 pm

biketechted, see the Emulator setup thread for my details on this...
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biketechted
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Re: Fork disassembly - spring/oil change; emulator install

Postby biketechted » Thu Apr 08, 2010 6:34 am

:cool
Jvalov1
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Re: Fork disassembly - spring/oil change; emulator install

Postby Jvalov1 » Tue Mar 22, 2011 12:30 am

I need to remove the inner fork pipe. Do you have an idea on how? i just need to remove it because im about to powdercoat my forks and frame
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Simon
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Re: Fork disassembly - spring/oil change; emulator install

Postby Simon » Tue Mar 22, 2011 3:19 am

Jvalov, (I think this would've been more fitting in a new topic of it's own in the Tech forum, but) you'll need to remove the oil seal retaining ring, in addition to the above disassembly, then inner and outer tube will pull apart. See the shop service manual that is available here: http://homepages.slingshot.co.nz/~shane ... _&_Parts_1 - also linked in a sticky on Tech ;-)
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