How to change front fork oil 2017 FJ-09

[howie333]

2017 FJ-09.  12K+ miles. 165 lbs. Manual states just to inspect forks @ specific mile intervals; but not to change fork oil and what weight. Local Dealer stated there shop usually doesn't change fork oil, and uses it uses a "0" weight. Can oil be changed w/o dissasembling the whole fork assemblies ? Manual states quantity (aprox. total 30 oz. for both fork tubes) and that it uses a Yamaha suspension oil 01.  not sure change interaval, but i think 12K miles is more than ready to change before I finally set this suspension up for my weight. What should be the change interval ? Just bought a Motool self sag measuring tool; so please help if can so I can order this fork oil. Can and should I use an aftermarket fork oil and what weight ? 

Thanks ; Howie...

 

 

[betoney]

25 minutes ago, howie333 said:

2017 FJ-09.  12K+ miles. 165 lbs. Manual states just to inspect forks @ specific mile intervals; but not to change fork oil and what weight. Local Dealer stated there shop usually doesn't change fork oil, and uses it uses a "0" weight. Can oil be changed w/o dissasembling the whole fork assemblies ? Manual states quantity (aprox. total 30 oz. for both fork tubes) and that it uses a Yamaha suspension oil 01.  not sure change interaval, but i think 12K miles is more than ready to change before I finally set this suspension up for my weight. What should be the change interval ? Just bought a Motool self sag measuring tool; so please help if can so I can order this fork oil. Can and should I use an aftermarket fork oil and what weight ? 

Thanks ; Howie...

 

 

Yes, you should change the fork AND shock oil on a regular basis, 'regular basis' for me is every 2 years or 20,000 miles.  You can do just a quick fluid change but -just my opinion- if you are going through the trouble of changing the old fluid, the forks should have a service inspection - new fluid, disassembly and cleaning, check bushings and seals.

When you pour out the old fork oil, you will be shocked at how nasty and grungy it is, just pouring the old fluid out leaves a lot of that sludge inside the fork orifices.

This video shows the quick and easy 'fluid change', not complete disassembly and cleaning.

 

[howie333]

14 minutes ago, betoney said:

Yes, you should change the fork AND shock oil on a regular basis, 'regular basis' for me is every 2 years or 20,000 miles.  You can do just a quick fluid change but -just my opinion- if you are going through the trouble of changing the old fluid, the forks should have a service inspection - new fluid, disassembly and cleaning, check bushings and seals.

When you pour out the old fork oil, you will be shocked at how nasty and grungy it is, just pouring the old fluid out leaves a lot of that sludge inside the fork orifices.

This video shows the quick and easy 'fluid change', not complete disassembly and cleaning.

Yes, I've viewed that video from Dave Moss. Very well laid out explanation. i guess I'll have to order that recomended 01 suspension oil, and follow Daves suggestion. Thanks for all comments. 

 

 

[2and3cylinders]

To remove the fork cap, necessary to remove the spring and spacer, an inexpensive spring compressor tool kit and a thread-on damper rod "grabber" to easily stroke the cartridge is required.  I clamp up the fork with plastic split collars made from PVC pipe in my trusty ancient Workmate clamping bench, and use a pair of ratcheting tie downs; one hook on a rubber hose cover socket extension through the axle hole and the top tie down hooks with a hose cover to the spring compressor.

Fork fluid of 16 Cst @ 40C (i.e., Torco RFF 5) should work well if you are 165# with the stock springs (that may be a little light) if you dial in the damping & preload front and rear.  You can use volume but measuring the air gap with the forks compressed, spring out, is the preferred method of setting fluid level; i.e., about 150~160 from top of tube compressed.

I doubt your bushings and seals are bad at that mileage though.  I drain the forks, fill them with inexpensive ATF as a flushing agent, pump and drain a couple of times, then installed the fresh fork fluid.  Setting the rebound rod length in the cap upon assembly is critical.

[howie333]

28 minutes ago, 2and3cylinders said:

To remove the fork cap, necessary to remove the spring and spacer, an inexpensive spring compressor tool kit and a thread-on damper rod "grabber" to easily stroke the cartridge is required.  I clamp up the fork with plastic split collars made from PVC pipe in my trusty ancient Workmate clamping bench, and use a pair of ratcheting tie downs; one hook on a rubber hose cover socket extension through the axle hole and the top tie down hooks with a hose cover to the spring compressor.

Fork fluid of 16 Cst @ 40C (i.e., Torco RFF 5) should work well if you are 165# with the stock springs (that may be a little light) if you dial in the damping & preload front and rear.  You can use volume but measuring the air gap with the forks compressed, spring out, is the preferred method of setting fluid level; i.e., about 150~160 from top of tube compressed.

I doubt your bushings and seals are bad at that mileage though.  I drain the forks, fill them with inexpensive ATF as a flushing agent, pump and drain a couple of times, then installed the fresh fork fluid.  Setting the rebound rod length in the cap upon assembly is critical.

What I've read, I'de just have to dump oil , and pump up and out (to measure), as Dave Moss Video shows to do. According to maxima's 5W race oil would be the Yamaha 01 (KYB) equivilant. Correct me if wrong. Thank You...

[howie333]

10 hours ago, howie333 said:

What I've read, I'de just have to dump oil , and pump up and out (to measure), as Dave Moss Video shows to do. According to maxima's 5W race oil would be the Yamaha 01 (KYB) equivilant. Correct me if wrong. Thank You...

If there's documentation or a video on that procedure, please let me know. TNX...

 

[2and3cylinders]

Moss takes short cuts...

IMO, only right is right.

[2and3cylinders]

What I'm saying is that even if one does not remove the fork cap, adding one step to the process can significantly reduce further bushing and seal wear.  That is after draining the used fluid and before refilling with fresh, rinse the crud out better by flushing with cheap ATF a couple, three times, then refill with new suspension fluid of your choice flavor.

Also, using wheel bearing grease, which is usually a lithium or aluminum complex, often contains moly EP, phenylmethyl silicone or is  calcium based is a no-no.  Even full synthetic and certain silicones are sometimes unwise to use on suspension seals and bushings over the long term.  I prefer a special light grease designed for this application named Slickoleum.  http://www.slickoleum.com/

Also 400 grit wet dry sandpaper is extremely coarse for this use.  Yes it's fast cutting but leaves scoring in the chrome that holds grime.  I'd use 600 minimum but 800 or even 1,000 or higher, followed by 3M Scotchbrite light gray then white pads, followed again by chrome metal polish with a quality microfiber towel, cleaned off with isopropyl alcohol wipes (kept off the rubber).  Certainly not a quick wipe after with an old T-shirt!!!  With suspension, cleanliness is next to godliness.

[betoney]

1 hour ago, 2and3cylinders said:

What I'm saying is that even if one does not remove the fork cap, adding one step to the process can significantly reduce further bushing and seal wear.  That is after draining the used fluid and before refilling with fresh, rinse the crud out better by flushing with cheap ATF a couple, three times, then refill with new suspension fluid of your choice flavor.

With suspension, cleanliness is next to godliness.

Exactly.  If you are only doing a quick 'dump and run', without disassembling the fork, at least take a few more minutes and rinse as much of the crud out as possible before filling with clean fluid. 

I am fortunate to live close to a dedicated suspension service center, I was talking to one of the technicians, he was telling me that disassembly and fluid change just takes a few minutes, most of the time involved in an annual service is cleaning.  All of those particles in the old fluid are also in every orifice and on every surface and over time can work like very fine sandpaper, so they meticulously clean and flush and then clean and flush again until its spotless before re-assembly.

[2and3cylinders]

I don't know about it taking just a few extra minutes if done carefully.

 Disassembly completely is somewhat a laborious process particularly with the FJ cartridge fork. You slap hammer out the oil seal with, believe it or not, the lower bushing. I once had that bushing jump out of its groove at the bottom of the slider end Get stuck iIs at the top of the slider. No matter what prying and pulling I tried I couldn't get it out until I very carefully and precisely took a hacksaw blade and vertically cut through the bushing Enough that I could squeeze inward and withdraw it.

 That entailed some extended sphincter Discomfort That was certainly not pleasurable!

 I keep this on the little shelf over my workbench desk as a reminder.

[koth442]

IMO the 'ole pump & dump works just fine. Only the trackbike ever gets a full disassembly & clean. That's only every few years.

[TomTracer]

On 2/8/2022 at 7:02 PM, howie333 said:

2017 FJ-09.  12K+ miles. 165 lbs. Manual states just to inspect forks @ specific mile intervals; but not to change fork oil and what weight. Local Dealer stated there shop usually doesn't change fork oil, and uses it uses a "0" weight. Can oil be changed w/o dissasembling the whole fork assemblies ? Manual states quantity (aprox. total 30 oz. for both fork tubes) and that it uses a Yamaha suspension oil 01.  not sure change interaval, but i think 12K miles is more than ready to change before I finally set this suspension up for my weight. What should be the change interval ? Just bought a Motool self sag measuring tool; so please help if can so I can order this fork oil. Can and should I use an aftermarket fork oil and what weight ? 

Thanks ; Howie...

 

 

I see no reason to change fork oil so soon. And fork oil is pretty much the same across name brands. Unless you just like to tinker, spend the time riding. My $.02,!

[howie333]

3 hours ago, TomTracer said:

I see no reason to change fork oil so soon. And fork oil is pretty much the same across name brands. Unless you just like to tinker, spend the time riding. My $.02,!

Thanks for replies. 1st i'm trying to get an accurate sag adjustment using the Motool sag measuring tool. it's easier esp. doing by myself. I'm not sure how important static sag is compared to the total rider sag. reading posts on YTube, rider sag should be 30-35% of total suspension travel, 137mm front forks, and 130mm rear, or 30-35mm total rider sag, I measure lifting bike front and rear separately, set to 0, then measure sitting to get full sag measuement; then set rebound damping according to feel.  many differnt ways to get hopefully same results.

[howie333]

Well; the Motool makes this job much easier. Here's where I'm at: 

looking for 30-35% sag of full suspension travel. should be approx. 35-40mm sag front and rear afaik. Front preload now measures 40mm turned in all the way-hard; rebound damping screw turned all the way out .

Rear preload now measures 35mm; least position-soft; rebound damping; 1-1/2 turns in from soft(middle of adjustment) good. I think it tells me, rear too hard a spring and front too soft a spring. I think i have correct sag now front and rear; but i'll take a ride tomarrow, but not sure what i'm looking for. Hopefully it'll handle better for the street and not go thru front tires so quickly. 

Thanks or replies... 

[2and3cylinders]

8 hours ago, KellyL said:

The next step is to put a zip tie around a fork and to check how much fork travel you use on an 'average' ride. If you blow through the travel despite having the 'right' sag level set, then that would strongly suggest the spring rate is too low for your weight and/or riding style.

This is certainly possible as the stock fork spring rate for 2017-8 is 0.75kg/mm, which is considered by some as suitable for a 75kg/165lb rider.

+1, which is what I initially stated.  Sag is just a way to gauge suspension action.  If it feels and works well for you (given you know what's happening technically) is what matters.  As long as it's not bottoming out, you want to use all but approximately the last 20 mm or so.  If braking dive is acceptable, which is a factor of both spring rate and compression damping, then you're in the ballpark.  Some like it stiffer with less brake dive, some want it softer.  It's all a matter of taste up to the point that the tire must be kept in constant and consistent contact with the road with the best size and shape contact patch without chatter or vibration and uncontrolled squirming.