Fork Oil

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Auron

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Nevermind, searched and found. Thanks though

 
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My bike was done when I got it, so I can't compare to stock....Many say the 1.1 kg/mm spring upgrade is a very cost effective mod. maybe 100 bucks while you are already there doing the fluid.

They say the stock fluid thins a lot very quickly. My spring manufacturer (Traxxion) recommends a 7wt fluid and 160mm oil height

 
Don't put 7 wt oil in a stock fork. You will not be happy.

Traxxion recommends a heavier weight oil only because they open up the orifices as a part of their re-valving package (to improve high speed damping). With the stock fork orifices putting heavier oil in will just make the fork a brick.

And I reject the non-sense that the stock oil thins quickly. It is thin when it is new (intentionally) and doesn't thin from there all that much. Some of the stuff that comes out of the suspension tuners (second hand) is laughable.

Cheap(est) fork upgrade is to just replace the wimpy stock fork springs with something more suitable for the bike (and your) weight. Service the fork and replace the oil with something close to the stock watery Yamaha 01 oil. A spring with about a .95 - 1.1 kg.mm rate should be good depending on your own heft and how much (or how many) you intend to carry regularly.

 
I'm pretty light so I'll probably go with a 1.0, I also got some Silkolene 2.5 full synthetic.

 
I was given and used 10 w fork oil from Traxxion and love the ride on the Omni 1.1 alone. From what I am told fork oil weight is very subjective to fork oil manufactures.

P83Y-FJR1300-2 Model 8983 '06-'10 Yamaha FJR1300, Shock Only,
Component
1 775.00 775.00T
SSH6x850 Shock Spring, Hyperco 6x850 (Suggested Retail $99.95) 1 99.95 99.95T
PD Traxxion Dynamics Parts Discount (10% off Retail for
FJR Owners)
-87.50 -87.50
SRB-FJR-1 Shock Reservoir Bracket, 06-09 FJR (Suggested Retail
$12.95)
1 10.00 10.00T
VSS6 6" Vented Shock Sock (Suggested Retail $16.95) 1 14.95 14.95T
OMNI1.10 Traxxion Dynamics Fork Spring Kit, OMNI x1.10
(Suggested Retail Price $109.95)
1 109.95 109.95T
FSBK11 Fork Spring Buffer Kit 11mm, used with Omni Springs.
(Suggested Retail $14.95)
1 14.95 14.95T
DROIL10 Fork Oil, 10 wt 2 9.95 19.90T
FRT Shipping/Handling/Insurance (Estimate Only, actual
shipping cost may be more or less)
20.00 20.00

 
Fork oil (or most oils) won't thin out with age. It will when hot, naturally, maybe on a real spirited ride might you get it hot enough, but you won't notice. It's formulated for hydraulics and for a wide range of temperatures. In the forks, it will get dark as it absorbs aluminum oxide from the internals, but for the most part the system is kinda sealed. You might get small amount of moisture past the seals over time which will tend to add a slight milkiness, but all minor normal stuff..... The stock FJR damping adjustments should be enough with 5W for anything the normal rider would need. Not that damping adjustments can compensate for every feel, but if you've got them cranked down to the low end and think you want a little stiffer damping then you can switch to a higher viscosity. Unless you're an experienced racer, you're not going to feel a lot of difference between 5W and 7W..... not sure I would have gone to 2.5W, sounds kinda thin to me. If anything I would have gone 5 or 7 to start.

 
Reminds me, I've got to call Cogent and find out what weight/height they used in my forks. Fork seal getting changed in the next couple of days.

Interesting thing I found with forks when cleaning the seals. Cogent packs heavy white grease to the underside of them. Maybe helps reduce stiction, or catch foreign objects?

 
The stock Yamaha 01 fork oil is not a 5 wt oil. More like a 3 wt. Silkolene 2.5 wt is the closest thing to Yamaha 01 at normal temps, and being a full synthetic doesn't thin as much as it warms. I would say that this is an excellent choice for a stock fork.

Here's where the oil viscosity matters: Yes, you can dial the adjusters to compensate for a heavier or lighter weight oil, but the adjusters in the stock forks only compensate for slow speed damping. Yes, there is some percentage of cross-effect to the high speed, but by and large the high speed orifices are fixed, so the weight of the opil you put in will affect that more than the adjusters do.

Once you modify anything to change the damping in the stock forks, everything changes. Most suspension shops recognize that the stock forks have high speed orifices that are too small, giving excessive high speed damping when the low speed is properly dialed in. So... the drill them out. A lot. And then they use a heavier viscosity oil in their setup.

Side note on fork maintenance: I was getting ready to run up and meet CanadianFJR up in the White mountains this morning, went to check air pressure in my tires and found a fork oil puddle under the front tahr. Oh shit!! This will not do!

Quickly ripped the NOJ neoprene fork protector off of the leaky side, pried up the dust seal out of the way, and made a quick clean of the seal with my "home made" (cut from a piece of old milk bottle) SealMate. Cleaned the seal all the way around twice, then wiped, pumped, wiped, and pumped and it looked good to go.

Was able to ride all day over some decidedly unsmooth roads and in some misty rain that gave me pause should my tire be greasy, and not a bit more leakage all day today. Total time to restore the seal was 15 minutes. Folks need to learn how to use these things. It saved my day.

Milk Bottle Seal Mate:

100_4032.jpg


 
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Yup, I've been doing the seal cleaning thing since my old motocross days when I was indestructible. I think this is the first time ever it hasn't worked, and this is after about 5 cleanings. It's not 'leaking'. but just a constant weep. Don't want it blowing on the way to Alaska in a few weeks.

 
The ironic thing about the seal leaking yesterday was I have a box full of parts and goodies from GP Suspensions sitting here in my office, just waiting for some lazy bastid to get off his ass and rebuild those forks. After >75k miles those oil seals don't owe me a thing. ;)

 
And I would guess the fork oil weight has very much to do with volume recommended for the components. I know I am at way less then stock oil height in the shock. So much I called to be sure. So less oil, heavier weight in my case. It would depend on the fork manufacturers parameters for weight and oil height to work with their set up.

 
Once you modify anything to change the damping in the stock forks, everything changes. Most suspension shops recognize that the stock forks have high speed orifices that are too small, giving excessive high speed damping when the low speed is properly dialed in. So... the drill them out. A lot. And then they use a heavier viscosity oil in their setup.
I'm not sure what you are saying here....do they drill out the high speed or low speed orifices? In the FJR's case there is nothing to drill out in the high speed circuit, they replace a spring loaded one way valve with a shim stack that has variable (and higher) oil flow. There isn't any technical reason to use a heavier viscosity oil after drilling out an orifice since that partially cancels what you are trying to achieve.....except to lower the cost of the oil. For some reason the manufactures offer the heavier weight oil (at a big discount) in 55 galleon drums and the suspension shops go through a lot of oil.

 
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And I would guess the fork oil weight has very much to do with volume recommended for the components. I know I am at way less then stock oil height in the shock. So much I called to be sure. So less oil, heavier weight in my case. It would depend on the fork manufacturers parameters for weight and oil height to work with their set up.
I think you would be guessing wrong. Oil height is a backdoor way of achieving the correct air space inside the fork after the springs and spacers are added. Heavier springs usually occupy more space than the springs they replace and some manufactures also include spring guides and different spacers....anything new that occupies space inside the fork is going to lower the recommended oil volume, the oil viscosity has nothing to do with the oil volume requirements.

 
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And I would guess the fork oil weight has very much to do with volume recommended for the components. I know I am at way less then stock oil height in the shock. So much I called to be sure. So less oil, heavier weight in my case. It would depend on the fork manufacturers parameters for weight and oil height to work with their set up.
I think you would be guessing wrong. Oil height is a backdoor way of achieving the correct air space inside the fork after the springs and spacers are added. Heavier springs usually occupy more space than the springs they replace and some manufactures also include spring guides and different spacers....anything new that occupies space inside the fork is going to lower the recommended oil volume, the oil viscosity has nothing to do with the oil volume requirements.
I would guess others would argue with you. My springs in no way shape or forum took up more space then the factory springs. Oil weight and volume make a huge differance even on original fork springs. Sorry not buying it but I will not argue with you I would say you need to talk to some companies like Hyper Pro, Traxxion, and Race Tech to see why they recomend less head space and in my case heavier oil. As you can see the Omni on top is smaller then factory.

spring%20guide.jpg


 
And I would guess the fork oil weight has very much to do with volume recommended for the components. I know I am at way less then stock oil height in the shock. So much I called to be sure. So less oil, heavier weight in my case. It would depend on the fork manufacturers parameters for weight and oil height to work with their set up.
I think you would be guessing wrong. Oil height is a backdoor way of achieving the correct air space inside the fork after the springs and spacers are added. Heavier springs usually occupy more space than the springs they replace and some manufactures also include spring guides and different spacers....anything new that occupies space inside the fork is going to lower the recommended oil volume, the oil viscosity has nothing to do with the oil volume requirements.
I would guess others would argue with you. My springs in no way shape or forum took up more space then the factory springs. Oil weight and volume make a huge differance even on original fork springs. Sorry not buying it but I will not argue with you I would say you need to talk to some companies like Hyper Pro, Traxxion, and Race Tech to see why they recomend less head space and in my case heavier oil. As you can see the Omni on top is smaller then factory.

spring%20guide.jpg
I'm not seeing any spacer with your OEM spring....probably because it is very narrow and barely fits over the damper rod taking almost no space at all inside the fork....in contrast your aftermarket system has both a thick plastic spacer and a spring guide. The air space is used to to give a progressive resistance at the end of the stroke to prevent bottoming and is very sensitive to volume changes. Too little air can result in excessive air compression and can blow out fork seals. Suspension companies recommend heavier oil because that is what they are able to buy in bulk sizes and use to develop their damping pistons and curves...the calculation of the correct air space is totally independent of oil viscosity because it doesn't matter what the oil weight is, it is not going to compress inside the fork and offer a progressive resistance. Its either going to move out of the way or create a hydraulic lock.

 
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It isn't about the spacer or the spring displacing more oil. It's about how much headspace you want over the oil. That space (air) over the oil surface acts like a logarithmically progressive air spring that boosts the physical coil spring in the suspension. If you put a stiffer spring in, and want a less progressive action, you would drop the oil level in the fork. That's all it amounts to.

PS - MCRIDER007 I haven't blown you off in regard to your question about what I meant with aftermarket fork damping mods and oil viscosities. I just haven't had the time to properly reply yet over the busy weekend. I will try to do that early this week. (this answer was a quicker one)

 
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It isn't about the spacer or the spring displacing more oil. It's about how much headspace you want over the oil. That space (air) over the oil surface acts like a logarithmically progressive air spring that boosts the physical coil spring in the suspension. If you put a stiffer spring in, and want a less progressive action, you would drop the oil level in the fork. That's all it amounts to.
PS - MCRIDER007 I haven't blown you off in regard to your question about what I meant with aftermarket fork damping mods and oil viscosities. I just haven't had the time to properly reply yet over the busy weekend. I will try to do that early this week. (this answer was a quicker one)
Fred, you don't have to answer my question unless you want to clarify your comments....I just thought it wasn't clear what you were actually conveying.

I agree its about how much headspace you want over the oil, but that headspace is going to be impacted both by the oil level and the suspension parts (such as a thicker spring/spacer or a spring quide) that are sharing the space above the oil level. You bring up a good point about using a stiffer spring, an air spring can add about 25 percent resistance to the spring's resistance.....if the new spring is 25 percent stiffer than the old spring than the air spring probably is not desired at its previous level and one could lower the oil level to reduce the air springs effect and save a little money on oil at the same time.

 
It isn't about the spacer or the spring displacing more oil. It's about how much headspace you want over the oil. That space (air) over the oil surface acts like a logarithmically progressive air spring that boosts the physical coil spring in the suspension. If you put a stiffer spring in, and want a less progressive action, you would drop the oil level in the fork. That's all it amounts to.
PS - MCRIDER007 I haven't blown you off in regard to your question about what I meant with aftermarket fork damping mods and oil viscosities. I just haven't had the time to properly reply yet over the busy weekend. I will try to do that early this week. (this answer was a quicker one)
Fred, you don't have to answer my question unless you want to clarify your comments....I just thought it wasn't clear what you were actually conveying.

I agree its about how much headspace you want over the oil, but that headspace is going to be impacted both by the oil level and the suspension parts (such as a thicker spring/spacer or a spring quide) that are sharing the space above the oil level. You bring up a good point about using a stiffer spring, an air spring can add about 25 percent resistance to the spring's resistance.....if the new spring is 25 percent stiffer than the old spring than the air spring probably is not desired at its previous level and one could lower the oil level to reduce the air springs effect and save a little money on oil at the same time.
It isn't about the spacer or the spring displacing more oil. It's about how much headspace you want over the oil. That space (air) over the oil surface acts like a logarithmically progressive air spring that boosts the physical coil spring in the suspension. If you put a stiffer spring in, and want a less progressive action, you would drop the oil level in the fork. That's all it amounts to.
PS - MCRIDER007 I haven't blown you off in regard to your question about what I meant with aftermarket fork damping mods and oil viscosities. I just haven't had the time to properly reply yet over the busy weekend. I will try to do that early this week. (this answer was a quicker one)
Fred, you don't have to answer my question unless you want to clarify your comments....I just thought it wasn't clear what you were actually conveying.

I agree its about how much headspace you want over the oil, but that headspace is going to be impacted both by the oil level and the suspension parts (such as a thicker spring/spacer or a spring quide) that are sharing the space above the oil level. You bring up a good point about using a stiffer spring, an air spring can add about 25 percent resistance to the spring's resistance.....if the new spring is 25 percent stiffer than the old spring than the air spring probably is not desired at its previous level and one could lower the oil level to reduce the air springs effect and save a little money on oil at the same time.
I agree with this aspect but not size of spring and blah blah. The spacer takes no room and the oil fill was with or without the spring buffer. You can make your stock springs respond differently with the head space and oil weight. Also I was not shipped a 55 gallon barrel of oil as my list above proves :)

 
I agree with this aspect but not size of spring and blah blah. The spacer takes no room and the oil fill was with or without the spring buffer.
No, the buffer doesn't displace any oil. What it does is take up some of the volume in the air space above the oil (buffers are not compressible).

So (just throwing out some numbers here) if the normal air space volume was 400 cc's and the buffer displaces 50cc's you'd want to drop your oil level by an additional 50cc's in order to get the same air spring assistance.

 
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