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Ok, you've gotten your BRP pretty much as you want it. You've
torn her down and greased everything, you've rewound the stator, you've
even finally figured out how to check the oil. As you hurdle over those
sandy whoops (west) or try to pound every root or rock into oblivion
(east) you realize that something is still not quite right.
| Those whoops are making you feel as though the bikes seat is
somewhere up around your L4 vertabrae and will require surgical
removal. That last 6" round pine root just transplanted your
wrists to the region about 3" below your elbows and the remaining
forearms look like Popeye's, minus the anchor tatoo. |
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Though the big XR is sprung and damped for almost everything
that is thrown at it, once you get specialized you begin to realize
there are flaws in the anti-boingo system.
I'm pretty much a dummy when it comes to suspension. I'm still
in Redneck Tech school when it comes to this stuff, so I've enlisted
Bruce Borynacks knowledge and work for the following project. He can be reached here
if you have any questions or suggestions.
Thanks goes out to Bruce for allowing me to use his work here
at The Pig Pen.
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The first step is to get at the fork internals. Removing the
forks from the bike isn't necessary, but if you feel ambitious, go
right ahead. Either way, be sure the bike is supported securely. If
you've never run into it, trust me, fighting with a 289lb pig with no
front forks is not much fun in my book!
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If you decide to just pull the internals
with the tubes attached to the bike, you may have to loosen
the top clamps with a 12mm tool. In stock setup, this won't be
needed, as the fork caps will be above the clamp already.
The caps are 30mm, or just under 1-1/16". If
you are removing the forks to do this job, loosen the caps
before removal from the clamps, it's much easier and you won't
risk scratching the chrome in a vise. |
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When you remove the cap from the tube, stand a bit to one side in
case spring tension
sends the ratchet into orbit. Once the cap is removed from the tube,
either lower the front of the bike to the ground to compress
the forks, or run a tiedown from the bars, down through the
front wheel, and then back up to the bars. Whichever you
choose, the forks need to be held in a compressed state. |
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Next step is to remove the cap from the now exposed
damper rod. Use a 17mm wrench as shown at left to hold the
locknut while spinning off the cap. After the cap, spin off
the locknut. You can either use a #2 allen to keep the damper
rod from spinning, or a small set of Vise-Grips. If you use
the grips, put cloth or paper towel in the jaws so you don't
scratch the surface. You don't want any burrs damaging the
bushing in the |
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Cylinder Composition (Big techy Honda word)
when you pull the damper out. |
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Remove the
spring and locknut. There may or may not be a washer on top of
the spring. The manual (I say again, you DO HAVE ONE, right? If
not, d/l it at left) shows a washer up top. Inside the damper rod there are two pieces,
the Adjuster Collar and Distance Collar. They are shown at left. The
collars are easily removed by quickly pushing the damper rod
down into the fork tube. The oil trapped below the damper will
force them up and out. Pay attention to which way the
smaller (Adjuster Collar) fits. Slotted side down. |
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The next step requires a couple of special tools. One
is a hollow 27mm allen head wrench, and the other is a 14mm
allen. Bruce managed to find all the pieces that just thread
together, shown at left. I had to weld up my own with whatever
pieces I could find. No fret, I just happen to have the
directions on how to make these here!
Either find someplace to borrow the tools, buy them, or
follow my simple directions, then proceed with sproinging your
boingers! |
| Here's where we start to get messy. If you've removed
the forks, it's not bad. If you haven't, then be prepared,
keep the small children and chihuahua away! You'll want
something to catch a quart of oil under the fork legs. I also,
being a neat freak, always have a few cardboard refrigerator
boxes kicking around for special occasions like this. These
puppies make cleanup easier, keeping all oil off the floor. |
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Remove the rubber plugs from the bottoms of the forks and
unscrew the compression adjusters all the way.
Now insert your newfangled tools and unscrew the
compression valve stack from the fork. Take a peek at the fiche,
part #13 is threaded into #11. You'll end up with the
compression stack at right.Oil everywhere!
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Clean everything up with a good supply of compressed air, brake
cleaner, and lint free paper towels. This is essential, Brawny
won't do for this application. If in doubt of the cleanliness before
reassembling a part, get out the brake cleaner. Buy 5 cans before you
even start. While you're at it, buy a good set of safety glasses. First
time you ricochet this vulgar fluid into your eyes, you'll see
(nothing) why.
Use a file or some other abrasive tool that you have good control
over to remove the staking on the nut of the stack. Don't remove any
more than you have to and don't nick the seals, washers, or valve.
After you get the 12mm nut off, but before you remove the anything
else, remove a little material from the circumference of the first two
threads. The staking distorts them and the valve will not slide off
over the bulge.
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Now remove the washers and valve. Be absolutely sure to keep
everything in order! Lay them out or hang them |
on a piece of coat
hanger, just don't mix them unless you feel you have a truly
photographic memory. Don't rely on the service manual or fiche, they
won't match.
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If a "plusher" ride is what you are looking for, now you
have to drill the valve to mimic a "Gold Valve". To the left
is the valve with the top two holes bored with |
| a #27 drill and the
bottom two are stock. Obviously this pic is just for comparison, you
want to drill all four holes. Doing this mod will require that you run
a stiffer valve stack, which Bruce describes below. |
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| The pic to the top right shows the stock (top)
and modified (bottom) compression stacks. This is Bruces' standard
"Fast Trail Rider" setup. It's plusher, yet will still
handle 5' drop offs and some mild jumping. To do this, he has,
starting from the right, removed the 2nd, 3rd, and 4th (1-22mm x
.10mm & 2-20mm x .10mm) shims and replaced them with two 21mm
x .15 shims.
On his own bike, he runs a setup for racing and jumping. I've
seen his videos and in his part of California, Pigs DO fly!
His setup changes out the first three shims, from the right,
(2-22mm x .10mm & a 21mm x .10mm) and replaces them with a
22mm x .15mm & a 21mm x .15mm.
This valving, in combination with .45kg Eibach springs, will
carry a 190lb rider with gear with true finesse. Bruce's comment
here is "It's as much an art as it is a science"........
I believe it. |
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Reassemble the valve stack back onto the core in the proper
order, again making sure that EVERY shim is clean. Install
and torque the nut to 25 to 30 INCH POUNDS, this is very
important. More or less will change the way the stack reacts to
the oil pressure.
Stake the nut as shown to hold it from coming apart. Do not use
a threadlocker, as you risk it wicking into
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causing problems.
That's it, you're done with the compression stack! If you
are a fly weight like me and run stock springs, then you can
button things up and call it a day. If you are in the 190lb or
higher range and need to run Eibach .45 or heavier springs, read
on and Bruce will show you how to increase the rebound damping. |
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The rebound stack is located at the end of the damper rod that was
attached to the fork cap. With the compression stack removed, just pull
up the rod. The rod will come out with a large aluminum piece (fork
damper) and a smaller piece on the end, slightly cone shaped, called
the Oil lock. |
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Once the assembly is out, slide the damper rod back down through the
damper to expose the rebound stack. There is a Teflon bushing in the
damper end, be careful not to score it with the threaded rod end. |
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