This is a guide to replacing the fork oil in your Zero motorcycle. With some basic tools you should be able to do this in half a day. The reason I wrote this is that not much info is available about Zero forks but these are Showa units that have been used on several bikes for years. Most of the bikes I have owned were used and old, most had probably never had the fork oil changed EVER! Most manufacturers suggest changing the fork oil every few years so I figured that my bike was already 5 years old and putting on the miles it was time. The forks were on a’15 FX and ‘16 FXS. The FX has longer forks but all models are very similar so the amount of oil should be the only difference. Although the oil that was drained looked pretty clean, especially compared to most forks I’ve ever seen, I think that it was worth doing and the suspension performance has improved. This is simply a guide for changing the oil, if your fork seals are leaking then the bushings are probably worn as well. This is a whole different thing as the forks will need to be disassembled, more special tools, and more oil. Not much harder to do but I didn’t need to go that far. Next time I will describe the full rebuild. I will add links to the tools used. This is all written down from memory so I don’t guarantee that everything is 100% correct but I will try and double check torque values etc. Double check your owners manual which has a torque table as well as a comprehensive suspension setup guide. If I think of anything else I’ll add it later. Feel free to share with the manual. Proceed at your own risk.
Jack up bike with your preferred method so the front wheel is off the ground. I used an MSR Pro stand.
Place a tie down strap around the handlebars up to the ceiling. This should prevent the bike from tipping once the front wheel is removed.
Remove the headlight cover, 2 3mm Allen screws. Note: when standing in front of the bike, the screw on your right side has a ground eyelet. Be sure to attach during reassembly.
Remove the brake line/ABS sensor wire clip on the right (facing bike) fork guard 2 phillips screws.
Remove lower fork guards or fender, 4 3mm Allen screws.
Remove the brake cable clip on the right side of the headlight bracket, 1 3mm Allen screw.
Remove 2 bolts from caliper, 8mm Allen bolts. Leave the caliper hanging on the rotor. Loosen fork top caps, 24 mm wrench. Just break them loose. Do this now as it will be much easier with the forks tight in the triple clamps.
Loosen the 2 6mm Allen front axle pinch bolts on the left side.
Loosen front axle with a 17mm Allen, then remove.
https://www.cyclegear.com/accessories/motion-pro-hex-axle-toolLean the wheel on whichever fork leg you want to do second.
Loosen top triple clamp pinch bolt on the either side with a 6mm Allen. Loosen either of the 2 pinch bolts on the lower triple clamp on the same side, 6mm Allen. Hold onto the fork leg and loosen the other pinch bolt. The fork leg will slide down and out.
I used a 5 gallon bucket with some rags at the bottom and a few small drain pans to work on the fork legs and keep them upright.
Loosen the adjustment screw on the top of the cover (can’t remember if it’s compression or rebound) all the way out. It should turn by clicking. Record the number of clicks and write it down. Do not force it!
At this time I wiped the leg down as it had lots of brake dust on it and since you’ll be stroking the fork through it’s full range and don’t want debris getting into the seals.
Remove the top cap with a 24mm wrench or socket. Be careful the cap is soft aluminum and is easily marred. I recommend a large adjustable wrench and put blue painters tape on the jaws.
Slide the upper leg down enough to expose the 2 holes in the sides of the spacer tube.
Now is where some special tools are needed. They can be purchased relatively cheaply or can be made with simple items.
https://traxxion.com/product/fork-spring-compressor-kit/ Install the compression tool into the holes. This is where an assistant is very helpful! Push the tool down far enough to expose the bottom of the jam nut below the cap. Have your assistant slide the holding tool or an open ended wrench around the rod holding the spring down.
Hold the cap from below with a 17mm open ended wrench on the 2 flats while loosening the jam nut with a 14mm wrench. Remember that you are looking at this upside down so make sure you are turning the nut the right way! Just loosen the jam nut then unscrew the cap and slide the cap and rod out.
Compress the spring with the tool again while sliding out the holding tool.
Lift out the spacer taking note of the order of assembly.
Hook the top of the spring with a wire hook or curved pick. Slowly raise the spring up out of the fork letting the oil drain into the leg. This is where it can get messy if you’re not careful! Once most of the oil has dripped off the spring, quickly transfer it over one of the small drain pans or a coffee can or whatever. Hanging it above the pan will let the remaining oil run off the spring.
Carefully tip the leg draining the oil into your other drain pan. Once you think it’s empty, slowly stroke it through it’s range and pour more oil out. You’ll have to do this a few times. More rags!
Pour fork oil (I used Honda oil SS-8 which is 10 weight?? But designed for use in Showa forks) into a graduated cylinder (I found a sweet one at a science store for a couple bucks) 350cc (cc = ml). I came up with this amount by measuring the oil drained from the leg, spring, etc.
https://www.motosport.com/pro-honda-ss8-10w-suspension-fluid?variant[PHO000Q]=PHO000Q-X001-Y001
With the fork compressed, pour the oil into the leg. Stroke the fork up and down slowly a few times.
Another special tool. You have to bleed the air out of the damper rod in the center of the fork. You can grab it carefully with a needle nose pliers or the special tool which is simply a 12” or so rod with threads on the end to capture the rod. It also has to be vented to let the oil out. Slowly stroke the damper rod up and down until it is smooth throughout its travel (6 or so times)The first couple times you will feel air towards the top of the stroke.
https://traxxion.com/product/fork-bleed-tool-fbt10x1/ Measure the oil level from the top of the fork tube to the oil while the fork is completely compressed. Should be 135-140mm. Add or remove oil as necessary to obtain the correct level.
https://www.motionpro.com/product/08-0121 Wipe down the spring which should be fairly oil free by now. Install the spring and spacer.
While lifting the damper rod all the way up, compress the spring, again with the special tool, and have your assistant slide in the holding tool.
Slide the rod and cap assembly into the fork and thread the cap onto the damper rod. Hold the cap, again with a 17mm wrench and tighten the 14mm jam nut.
Compress the spring and remove the holding tool. Remove the compression tool.
Slide the upper fork leg up until it meets the cap. Turn the cap counter clockwise (loose) until you hear a light click, then tighten by hand. This should ensure the cap doesn’t cross thread as mentioned before it is soft material.
Wipe off the leg and stroke it a couple times.
Slide the leg back into the triple clamps and snug up one of the bolts. Now set the height by loosening the bolt and raise or lower. Pro tip, use the other side for reference. The top of the fork leg should stick up approximately 10mm above the clamp. Also make sure that the reflector is facing out!
Snug all 3 bolts.
Lean the wheel on the leg you just installed.
Remove the other leg and repeat the process. This one will take way less time because you just did it and now you’re practically an expert!
Reinstall the axle with a little grease. Be sure the ABS sensor on the right is in place. Tighten the axle to 19 Nm. Tighten the 2 axle pinch bolts to 13 Nm.
Install and tighten the 2 caliper bolts and tighten to 26 Nm.
Spin the wheel to make sure it spins freely and test the brake.
Torque the triple clamp bolts 6 to 23 Nm.
Tighten the fork caps. They don’t have to be super tight, you’ll have a feel of how tight they were when loosening them. Turn the adjustment screws in to the desired number of clicks.
Put the bodywork back on, don’t forget the ground wire!
Go ride!
Say10
