Installing emulators and springs

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Many of these instructions are derived from the FAQ article about changing fork seals. You should read it before you start on this.

Test subject for this exercise is a 2003 EX250. The fork oil had most likely never been serviced (no!!) and it sure seemed like it. The front end would feel like it was slowly drifting when on the highway at 60mph+. This may have been the soft stock springs in combination with the reduced damping caused by old fork oil. It was time for something else...

The owner decided on 0.75 kg/mm Sonic Springs, which were a compromise between the weights of the bike's two regular riders. Here's how the Sonic Springs compare to the stock ones in length:


As the spring rate was going to be upgraded, it was decided to get some better damping also. This came in the form of RaceTech gold valve emulators.

Here are the steps:

Step 1. Remove your lower and upper fairings.

Step 2. Remove the cotter pin (if present, as it should be) and break loose the front axle nut with your breaker bar.

Step 3. Remove the handlebars. Each bar is held by two hex bolts. It is not a good idea to let the handlebars dangle by the cabling, particularly in the case of the right handlebar and the brake line. There may be more elegant solutions, but just taping the left and right bars together with some masking tape over the instrument cluster works.

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Step 4: At this point you need some way to support the front end of the bike. A floor jack beneath the oil filter plate worked here.


Step 4a: Remove the fork caps. The fork caps are held in place by a small ring that sits in a groove. The caps are preloaded by the fork spring, and there is a lot of pressure there, so be careful! The fork seal article suggests a couple of alternative methods to remove these that may or may not work for you. A two-jaw puller, like the one used here, is very easy and makes the work quick. You also have a controlled method for releasing the spring tension, which is probably the best reason. A 3-pack of pullers from Harbor Freight runs about $15. It is worth it.

Step 4b: What you do is install the jaw puller and compress the spring enough to provide easy access to the ring. Then you use a $3.99 Chinese secret weapon:


This makes for light, less frustrating work. Maneuver one of the picks to sort of pry up the ring, then insert the other pick in order to leverage it out of there. The rings readily bend, so this is not too hard, though it may take a few minutes to master the technique.

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Step 4c: Once that ring is out of there, there is nothing (other than the jaw puller) holding the COMPRESSED spring in. At this time, put a shop towel or something soft on your gas tank so that if the cap flies out it doesn't ding your tank.

Slowly, carefully, loosen the jaw puller and grab the cap before it goes flying.

Repeat this for the other fork.

Step 5: Measure the fork height, so you know what to set it to when you reinstall. The spec is 12mm, and this bike was dead on. If your bike is set up differently, record the height so that you have an idea of what to set it to later. The picture is blurry, but you get the idea. The $10 Harbor Freight calipers are useful for this kind of small measurement.


Step 6: Unbolt the brake caliper and support it somehow. A coat hanger or piece of string or rope works:


Step 7: Remove the front wheel. (You did remember to support the front end, right?) Don't lose the spacer, axle nut or axle nut washer.

Remove the 4 bolts holding on the front fender.

Step 8: Now loosen the pinch bolts that clamp the forks to the triple tree. Hold the fork while you loosen the upper (12mm) and lower (14mm) bolts, in order to prevent the fork from violently falling to the ground. Slide it out gently.

You can remove the stock spacer, washer, and fork spring at this point. Some fork oil will come out, so be prepared with a shop towel.

Step 9: Drain the old fork oil into a suitable container. Pump the fork to get most of it out.

Step 10: Clean the inside of the forks with brake or parts cleaner. Pour or spray some in and pump the fork, then drain. When it comes out clean, that's good enough.

Step 11: More disassembly. With the somewhat cleaned forks off the bike, you have to unbolt the damper rod from the fork in order to remove it. This requires a tool that most of us don't have, but (surprise surprise) Harbor Freight does for $12.99. It's a long hex key:

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Some people talk about removing the damper rod with the forks on the bike. Our guy found that too unstable and felt that holding the fork in a vice was much easier and less frustrating. So, clamp it in a vice (clamp only the flat-edged area that mates to the wheel) and use your 6mm hex bit socket to loosen it. A trusty Craftsman breaker bar with a not-so-small amount of force broke it loose. It does take quite a bit of effort, and the long hex key may flex, but you should be able to break it free with enough effort. FYI: If you don't have a breaker bar, you are INSANE! There are untold times when this is the best tool to use. Thread locker was on the damper rod, which probably explains the difficulty. An estimate of the force necessary to get it loose is about 60-70 lb-ft of torque.

With this done, the damper rod and top-out spring will be released and you can remove them.

Aside A: Gold valve emulators! These pictures give you an idea of how the emulator sits atop the damper rod.

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We are now ready to start following the directions that are supplied with the GVEs. The summary is:

(a) drill out the old compression damping hole to 5/16" and add four more 5/16" holes to de-restrict the damping.

(b) measure out new spacers

(c) set the fork oil level

(d) button up the fork

Check out this Sport Rider article for more info on why you do this.

Step 12: Drill out the existing compression hole to 5/16". Do this by carefully aligning the bit on the drill press with the existing hole. Titanium drill bits from (you guessed it) Harbor Freight did the trick. This may be the time to find a friend or a machine shop with a drill press if you don't have one.


Step 13: Drill out the second hole. Per instructions, the centers of each hole are separated by 10mm. Alternating holes are drilled perpendicular to one another. The pictures will make this clearer. The second and third holes are on either side of the stock hole, i.e... the stock hole is in the middle.

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Comparing the modified rod (left) to stock (right):


Step 14: De-burr and chamfer the holes, inside and out. Racetech instructs you to do this in the directions. When you chamfer the holes, you are essentially getting rid of the sharp 90-degree corners where you drilled the hole and replacing the straight line with a beveled edge. This makes the fluid (fork oil) flow better through the holes, which is why the extra holes are there in the first place.

One way to safely chamfer the hole would be to use a small circular file. With the file held at a 45-degree angle to the rod, file evenly around the holes until the outside edge is beveled. Repeat for the inside edge. You'll need a file that has a smaller diameter than 5/16" (the diameter of the hole) in order to do this effectively.

Another way would be to use a rotary tool (dremel) with a sanding bit. Do basically the same process as above. The dremel makes for light work, but it is much easier to make a mistake by removing too much material. It is also much easier to have an accident when chamfering the inner surface, since the tool is mostly inside the damper rod, and if/when it catches the wrong edge the tool can fling about violently. A drill bit on the dremel is most definitely the wrong tool for the job.

Arguably the best way to make a beautiful chamfer for the outer surface is to use a countersink drill bit at the same time as the first hole is drilled. This will make a perfect chamfer on the outside edge. The inside edge will still require a tool like a dremel or a file.

After chamfering, use some sandpaper to smooth things out further.

Step 15: Clean up the modified damper rods. There will be lots of metal shavings. Spray brake cleaner in and out to clean things up.

From here on, try to be as clean as possible. Don't let foreign objects or debris fall into your forks.

Step 16: Put the damper rod and the top-out spring back into the fork tube. Install the fork spring to press the damper rod to the end and hold it in place. Then screw in the damper rod bolt. Torque this to 14.5 lb-ft.


Step 17: Now that the damper rod is back in place, the next major step is to measure out your fork spacers. For this part, see also Where can I get some preload spacers?

The length of the fork spacers determines the preload setting for the fork spring. Longer = more preload. Sonic Springs recommends you set the preload to 1/2", so that's what was done. In order to measure this out, place the GVE atop the damper rod, followed by the new spring, followed by TWO washers (supplied by Sonic). Then, place the (not yet cut, long) spacer tube in and mark the tube at the top of the fork tube (let's call this length L). Next, measure (with the calipers) the width of the fork cap (~14mm) and the length down from the top of the fork tube to where the top of the fork cap sits (in the range of ~11mm) For 1/2" (12.7mm) of preload you want the top of the fork cap (with the spring uncompressed) to sit 1/2" above the ring-groove, so that means cutting the spacer to L - (14 + 11 - 12.7). On this bike that equated to about 93mm.

Sonic springs gives you a long tube of PVC pipe to make the spacer. Cut the spacer to length and clean up the edges to prevent loose pieces of PVC from floating around.

Step 18: Add fork oil and bleed. This is done without the GVE or spring or anything else (other than the damper rod) in the fork tube. Add enough oil so that when the fork is completely extended the oil still covers the inner tube. Pump the fork up and down a while until you hear (and see) no more air coming out. Not too complicated.

Step 19: Assembly and setting the fork oil level. As gently as possible so as to minimize a big splash of fork oil, drop the GVE down into the fork tube. Fully compress the fork. Measure the distance down from the top of the fork to the fork oil. This is the important thing: the fork oil level. Racetech recommends 130mm of fork oil. Sonic Springs (and others on this website) suggest 115mm. 125mm was chosen by our rider. Remember to take your time. Set up a jig or something to hold the fork upright at this point so you don't spill fork oil.

Step 20: Install the fork springs, then a washer, then the spacer, then another washer. Place the fork cap back on. If everything is done correctly, the cap will be 1/2" (preload setting) above the ring. So, you'll have to compress the spring to get the circle/ring clip (or new circlip) back on:


Step 21: Carefully place the fork into the triple clamps and clamp lightly.

Step 22: Use your trusty jaw puller tool to compress the spring and set the fork cap in place with the clip.

Step 23: Set the fork height to (probably, depending on your goals) what it was before. That was 12mm above the top triple clamp on this bike. Don't torque yet!

Step 24: Install the fender.

Step 25: Install the brake caliper. (torque 24 lb-ft)

Step 26: Install the front wheel. (axle nut torque 65 lb-ft)

Step 27: With the front end still supported by the jack (or whatever you're using) loosen up each fork in the triple clamps (one at a time, not both) in order to reduce any kind of imperceptible imbalance in fork height between either side. Do this for one side, then re-tighten, then repeat for the other side.

Step 28: Torque the pinch bolts in the triple clamps to spec. Upper is 14.5 lb-ft, lower is 22 lb-ft, according to the shop manual.

Step 29: Remove the jack. The front end should be stable now.

Step 30: Reinstall the handlebars.

Step 31: Reinstall the fairings.

Step 32: Cautiously take your bike for a test ride.

Total time for an experienced machine worker, but who was a total newbie to forks, including clean-up and lunch break, was 6 hours or so.

Adjusting the emulators

The Racetech instructions will tell you how to adjust these to your preference. Just note that after you have the GVEs installed, it's possible to remove them for adjustment by just dropping the handlebars, popping the fork caps, washers, spacers and springs, and fishing them out with a little loop of copper wire. There's no need to drop the wheel and remove the forks just to change those little adjustment springs.


From our owner: Like some other members have posted, the new suspension really soaks up bumps. It is incredible. I tested out some reflectors (you know, the kind on the lane markers) at 40 mph, and by and large there was very little energy transmitted to the handlebars. And yet the increased stiffness is very noticeable when it comes to braking--there is weight transfer (as there should be) but the dramatic nose-dive is eliminated. SCORE!

I would definitely recommend the stiffer springs and the GVE's to anyone who is interested in riding their EX250 for anything longer than a year. It is worth it. I feel more confident and safer because the bike feels planted and responsive.

If anything, the great front suspension now highlights the weakness of the stock rear suspension...