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.
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.
Lets Get Dirty!
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!
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.
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.
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
Cylinder Composition (Big techy Honda word) when you pull the damper out.
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.
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.
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!
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.
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.
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.
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.
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 the valve stack and 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.
On the Rebound!
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.
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.