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Fork oil: how much, what brand, etc

Thud300

Thud300

Guest
Guest
So, got a hankerin' to change the fork oil on my 98... procedure looks straightforward, need to get a murph tool... looking for seasoned advice on oil and amount. Forum research says 15w is the way to go.
 
If you have stock forks than yes 15 will get you about the best ride.  Delray is always good.  If not stock than who knows.
 
Yes, fully stock gen 2 forks to the best of my knowledge. No idea if they have ever been serviced. I just recently decided to explore the preload adjusters and found they were run all the way in by the PO, so I ran then all the way out then set them to about 4 marks, much less of a jarring ride. MOB, nice tip about using a strap with the front axle installed to insure full compression during fill.

Smithr1, I presume you meant Bel-Ray oil. Some have said to use 10w in Bel-Ray instead of 15w because it's thicker?

That was quite a thread to read, heck of a way to learn about fork seals, glad she got it all sorted out.
 
I linked it because it had the measurements I gave, and also as a pre emptive warning on overfilling,

Best of luck on your service  :great:
 
Got er done today. Went to the shop so all my tools were handy. Of course I go in and instead of working on my bike, find myself bailing out one of our lube techs who was trying to replace a ball joint on his truck and got in way over his head  :-[ so then having saved him from himself, found myself a little short on time.

So I went to plan B, which is essentially the method laid out in the tech archive, summer 2010 edition of the Concourier.  The Mityvac and my shadetree fork servicing doodad worked great, extracting and refilling each fork with the exact amount of oil. The whole thing took a little over two hours. I ended up using Suzuki 15w fork oil  :eek: cause it was dirt cheap at the local stealer, $3.99 a quart. It was also the only 15w fork oil they had.

After the work was done, went for about a 40 mile ride. Felt great.  :great: Once again, being a COG member pays off.

Oh, and what an AMAZING STENCH that old fork oil has.  :sign0137:

 
MAN OF BLUES said:
When I worked for Yamaha, e used to call it "fish oil"...  :rotflmao:
I swear all the factories used it...
Click to expand...

Dating yourself MOB!  ;D We called it that when I was racing, bought a new '77 YZ250, in the crate. One of the things I did before I used the bike was change the fork oil. Sure SMELLED like fish oil.....
 
Rain Dancer said:
MAN OF BLUES said:
When I worked for Yamaha, e used to call it "fish oil"...  :rotflmao:
I swear all the factories used it...
Click to expand...

Dating yourself MOB!  ;D We called it that when I was racing, bought a new '77 YZ250, in the crate. One of the things I did before I used the bike was change the fork oil. Sure SMELLED like fish oil.....
Click to expand...

I'm not ashamed to say my first bike purchased was in 74, a Yammy 1973 RT3 enduro 360..
Same year I began working in a local Yammy dealership as a second job, nights, prepping and building new crate bikes, and servicing everythingnelse that came in.. did that for close to 5 years so I could afford to race my 74 KX450, work all week to spend the money on the weekend, andnrepeat...

It was fun, and we actually collected the "fish oil" in containers, and saved it for "dirty deeds" and pranking people... we had about 20 gallons at one point, and the boss made us get it out of the shop, because his kid ran a jug over with a fork lift... and "perfumed" the place... :rotflmao: :rotflmao: :rotflmao: :rotflmao:

Ahhh funtimes as a kid it was.. funtimes.
 
Those fish died a looong time ago  :sign0137:

So that was probably 18 year old grinding compound I extracted out of the forks. Yuk.
 
If you want to experiment with different fork oil weights, the drains are the way to go.  However, from a periodic maintenance standpoint without the drains, removing 1 more nut gets you access to the often neglected steering head bearings.  I do the fork oil and bearings every 2 years and just leave the forks attached to the lower triple clamp.  This makes it easy to secure the assembly, vertically, up against the work bench to clean and repack the lower bearings using a large syringe full of grease.  When complete, stuff the whole thing back into the steering head, attach 1 nut and the fork tubes are already set to the correct height.
 
Thud300 said:
<SNIP>

So I went to plan B, which is essentially the method laid out in the tech archive, summer 2010 edition of the Concourier.  The Mityvac and my shadetree fork servicing doodad worked great, extracting and refilling each fork with the exact amount of oil. <SNIP>
Click to expand...

Can anyone tell me if the summer 2010 Concourier is available online anywhere?

Also, what's the "shadetree fork servicing doodad"?


JA
 
John_Atkinson said:
Thud300 said:
<SNIP>

So I went to plan B, which is essentially the method laid out in the tech archive, summer 2010 edition of the Concourier.  The Mityvac and my shadetree fork servicing doodad worked great, extracting and refilling each fork with the exact amount of oil. <SNIP>
Click to expand...

Can anyone tell me if the summer 2010 Concourier is available online anywhere?

Also, what's the "shadetree fork servicing doodad"?


JA
Click to expand...

Behold, the shadetree fork servicing doodad.



It's simply a piece of 1/8" brake pipe with one flared end cut off at an angle, with a #6 stopper positioned by a couple of pieces of vac tubing, and one more piece of vac tubing to serve as a marker for the existing oil level and to verify the fill level of the new oil. The stopper does not fit the tube, it serves as an indicator that the tube is fully inserted; at the very bottom of the fork tube there is a dimple in the center that can be felt when inserting the brake pipe, and that is the point from which the old oil was extracted.

I started by getting the front wheel off the ground so the forks were fully extended, then using the pipe as a dipstick to measure the previous oil level, and adjusting the 'marker' to the old oil level so it would be retained. Then the pipe was reinserted, each time finding the dimple at the bottom, and the old oil was Mityvac'd out. Here's the extraction.



The graduated jug on the Mityvac measured about 310 ml's of oil from each fork tube. Because the Mityvac I own can also create pressure by turning a valve, I cleaned out the jug and tube of nasty oil, filled it with 310 ml's of new oil, and used the Mityvac with the brake pipe to fill the fork tube from the bottom up. (Note, the 1/8 brake pipe made this take a while, 3/16 would be a faster option.)
The oil level was then verified with the oil level marker that was set before the old oil was removed. In hindsight I would make this marker piece a bit longer to make the new oil level easier to see.

The results were good, no leaks or surprises afterward. I do recommend using a speed handle to back out and restart the caps, it's far easier to push down and turn at the same time;  and using index marks to help get the threads started.

The article I referenced is found in the Tech Pages. Clicking the download link will get you the whole magazine containing the article from the archive.

 
Just a thought:  If you don't know the history of your bike with regards to fork oil changes, I would suggest measuring the level of the oil and not rely on volume removed, at least for the first time.

Make fluid level measurement, for all years, with fork spring removed.
Measurements for factory fork configurations, only.

1986 - 1993:  Fork fully extended, air assist forks
355 mm from top of fork (13.98 in.)

1994 - 2006:  Fork fully compressed, pre-load adjustable forks - no air assist
171 mm from top of fork (6.73 in.)
 
Jim said:
Just a thought:  If you don't know the history of your bike with regards to fork oil changes, I would suggest measuring the level of the oil and not rely on volume removed, at least for the first time.

Make fluid level measurement, for all years, with fork spring removed.
Measurements for factory fork configurations, only.

1986 - 1993:  Fork fully extended, air assist forks
355 mm from top of fork (13.98 in.)

1994 - 2006:  Fork fully compressed, pre-load adjustable forks - no air assist
171 mm from top of fork (6.73 in.)
Click to expand...

This was how I planned to do it, with the front wheel off and using a strap with the front axle in place to compress the forks, per MOB's suggestion. But having to use most of the available time to bail someone else out, plus not really having any front suspension issues except the need to get the oil changed, led me to this combined level and volume measurement method that didn't involve pulling the front wheel. Basically, I trusted that the original level was correct.

Did i mention how BAD it smelled? It really stunk up the entire area for a couple days...
 
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