Fork Oil Recommendations

[ST1100Y]

Bel ray 10# use this fork oil for years.

I'm too outing myself with BelRay 7W here... works great on the combination of Hyperpro springs and frost beaten, patch-worked alpine roads...
(I also like it over its low degrading properties, leaving noticeable less sludge in the fork bottoms... it's still kinda clear after 36,000km/22.5Kmiles (my change interval), where products from other MFG's turned into black goo...)

 

[wizel]

Many drive Wilbers springs in Europe.
Thus, they also use Wilbers fork oil. Viscosity 10.
greetings from germany holm

 

[Igofar]

I’ve used Belray, and BMW 7 weight oil, in forks that were built using sonic springs for folks, and the lighter weight oil worked well with slightly heavier springs at at oil depth of 125mm compressed, with a preload spacer of 130mm,for the folks who purchase their jeans in the Husky Children’s section at Sears.
However, I’ve been using supertech ATF fluid in all the builds using stock springs, and nobody has complained about in the past 15 years or so.
One thing I have seen OFTEN is how black and nasty the Honda brand fork oil turns between oil changes!
And the bushing are almost always worn off enough to need replacing at each fork oil change.
The ATF fluid never smells that bad, or turns that black, and the bushings still look new between oil changes.
I will continue to use ATF fluid in my forks, and the forks I rebuild for folks, unless they specify something else.
And those that have, often went back to ATF fluid on their next fork oil change.

 

[Daboo]

So what fork oil do we use??????

I'd try Igofar's recommendation and use ATF oil. What could it hurt? If you like it, use it from that point on. If you don't...try something different. When you find what you like, stick with it.

Sometimes you can find the same thing under a different name. When you put "Motorcycle" in front of it, suddenly, it costs more. Just an example. You can buy some extremely high priced chemicals to clean rust and stains off your exhaust pipes. You can also buy Clorox Gel toilet bowl cleaner for far far less, that will do the same thing. Why? Because both have sodium hydrochloric acid in them as the active ingredient.

So why not take an expert's opinion?

Chris

 

[Art Franz]

Rebuilt my forks twice now. First time I put 10weight Motul, it was too stiff. Drained that and diluted it 50-50 with 5 weight Motul and that was just right. The 2nd time Larry Igofar did the job and we put in that same 50-50 blend, Motul again, and now it’s leaking again. But this time I can see some fine vertical scratches on the fork. I live off a gravel road so that’s likely what caused that problem. And I’ve tried the flexible plastic trick to no avail, didn’t get any dirt out of there either.
Does anyone know of a way to repair those scratches? Besides buying new forks?

 

[Obo]

Does anyone know of a way to repair those scratches? Besides buying new forks?

No idea how well this works though....

All methods seem to be "remove high spots", "fill low spots" & polish.
It's a fine tolerance in there and needs that mirror smoothness to prevent tearing the seals.

 

[Art Franz]

No idea how well this works though....

All methods seem to be "remove high spots", "fill low spots" & polish.
It's a fine tolerance in there and needs that mirror smoothness to prevent tearing the seals.

Thank you for that. Never thot of crazy glue. I use a high end epoxy to bed rifle actions (hobby) and it sticks really well to metal, plus you can sand it when it’s dry, or 00 steel wool in this case, was thinking of trying that. It’s oil proof as well, not sure how well crazy glue stands up to oil.

I’ll do a report on that when I do the repair.

 

[Larry Fine]

No idea how well this works though....

While I didn't make such a production out of it, I repaired one of the tubes on my '96 CB750 with super glue when I rebuilt the fork several years ago. It had several light scores, smooth but you could see and feel them, and one pit about 3/16" across and deep enough to be black at the bottom.

After I was done, you could still see the scores, and the pit looked like nothing changed. But, every bit of it feels like glass. I could not feel anything. It's still smooth and dry to this day. As said, always position the blade so you're scraping around the tube, never along its length. I used a sawing motion.

 

[Honda-st-team]

I’ve used Belray, and BMW 7 weight oil, in forks that were built using sonic springs for folks, and the lighter weight oil worked well with slightly heavier springs at at oil depth of 125mm compressed, with a preload spacer of 130mm,for the folks who purchase their jeans in the Husky Children’s section at Sears.
However, I’ve been using supertech ATF fluid in all the builds using stock springs, and nobody has complained about in the past 15 years or so.
One thing I have seen OFTEN is how black and nasty the Honda brand fork oil turns between oil changes!
And the bushing are almost always worn off enough to need replacing at each fork oil change.
The ATF fluid never smells that bad, or turns that black, and the bushings still look new between oil changes.
I will continue to use ATF fluid in my forks, and the forks I rebuild for folks, unless they specify something else.
And those that have, often went back to ATF fluid on their next fork oil change.

You talk about all this work you continue to do LET'S SEE THE PICTURES

 

[Andrew Shadow]

But this time I can see some fine vertical scratches on the fork.

Depending on how deep they are, the damage can often be blended out. A quality shop that overhauls hydraulic cylinders often has the blending compounds and tools needed for this.
Years ago I had a couple of nicks in a fork tube that were so nasty that I thought that I was going to have to replace the tube, or at least have it re-chromed. An old bugger in an hydraulic shop said that I'd be wasting my money and that he could blend it out. Other than the discoloration in the chrome in the blended area the repair was not discernible from the surrounding surface after he was done, and it never caused the seal to leak again.

 

[Obo]

Thank you for that. Never thot of crazy glue. I use a high end epoxy to bed rifle actions (hobby) and it sticks really well to metal, plus you can sand it when it’s dry, or 00 steel wool in this case, was thinking of trying that. It’s oil proof as well, not sure how well crazy glue stands up to oil.

I’ll do a report on that when I do the repair.

Depending on how bad it is, @CYYJ did a write up on fixing them in his fork overhaul thread.

Article [13] - ST1300 Front Fork Overhaul: An Illustrated Bibliography | ST1300 Articles

Hello All: This past winter, I wanted to overhaul the front forks on my 2012 ST 1300. When I began looking for information about how to do this, I knew nothing about the front forks, they were a complete mystery to me. I started doing research here in our forum and discovered that we have a...

www.st-owners.com

"
Evaluating and Correcting the Condition of the Fork Tube
The fork tube is subject to impact damage from rocks and hard-shelled insects. If it has suffered impact damage, there’s not much you can do about the impact crater, but what you can do is make sure that there are no ridges around the crater that stick up and will damage your new fork seal.

I found a small impact crater on one of my fork tubes. I used a Norton ICE 2000 grit foam finishing disc to abrade away the raised edges of the crater, and followed up by polishing the outer surface of both fork tubes with Meguiar’s Mirror Glaze 9 Swirl Mark Remover. Both are specialty products available from auto body industry suppliers, they are not usually found at consumer retail stores. Fine grade bronze wool (not steel wool) could also be used.

There’s no point in perfecting the condition of the fork tubes, only to scratch them up when re-installing them, so take a moment to clean the inside of both the upper and lower fork clamps (still on the motorcycle) with a soft 3M Scotch-Brite pad, bronze wool, or similar gentle abrasive before you put the forks back on the motorcycle.
"

 

[oilspot]

I know this is an older thread, but had a few questions after I rebuilt my forks. I polished the tubes before rebuilding to get everything smooth and shiny. The bench grinder with a polishing wheel seemed to do well.

When I purchased fork oil, the honda dealer really encouraged me to use the stock fluid and weight. However, once assembled and on the road the shocks seem fairly stiff. At a standstill, I have difficulty compressing the forks with my bodyweight. Once I'm rolling down the road I can tap the front brake and get a decent fork "dip" when the shocks compress.

I trust @Igofar experience, and wonder if I should pull the forks and replace the fork oil with ATF. The forks have about 1,500 miles on the new bushings and seals at this point.

I was getting some minor instability from buffeting on the interstate highways, which I was able to minimize by increasing the stiffness of the rear shock. I don't know whether ATF would help with this minor issue or aggravate it. Any experience or advice would be appreciated. I'm average height (5'9" and about 165lb).

 

[RaYzerman]

ATF is an unknown unless you know the centistoke values...... go to the chart and pick an oil lighter than SS-8 centistoke values, e.g., some 7 weight....

 

[acedantinne]

I'm curious what everyone is using for fork oil. I need to do the seals so I figured I would clean and refill them. @CYYJ mentioned 10w oil.

I stopped at the local Honda dealer and they didn't have any which I was told was Honda SS-8. They did have some 10w oil in Maxima Racing Oils, for $17.49 a quart. I know I'm a tight wade, but geeze this sounds expensive.

What are you guys using? With my 83 V65 Magna I used Honda Fork Oil years ago, but there is a nagging feeling in the back of my mind that someone then said I could use tranny fluid. Is this absurd?

Anyway, I'm interested to know your thoughts.

Bel-Ray=Amazon

 

[Daboo]

I know this is an older thread, but had a few questions after I rebuilt my forks. I polished the tubes before rebuilding to get everything smooth and shiny. The bench grinder with a polishing wheel seemed to do well.

When I purchased fork oil, the honda dealer really encouraged me to use the stock fluid and weight. However, once assembled and on the road the shocks seem fairly stiff. At a standstill, I have difficulty compressing the forks with my bodyweight. Once I'm rolling down the road I can tap the front brake and get a decent fork "dip" when the shocks compress.

I trust @Igofar experience, and wonder if I should pull the forks and replace the fork oil with ATF. The forks have about 1,500 miles on the new bushings and seals at this point.

I was getting some minor instability from buffeting on the interstate highways, which I was able to minimize by increasing the stiffness of the rear shock. I don't know whether ATF would help with this minor issue or aggravate it. Any experience or advice would be appreciated. I'm average height (5'9" and about 165lb).

If you trust Igofar's experience, then go with that. There's a lot to be said for having the mental confidence in trusting where your advice came from.

I'm not an expert, and I don't even own an ST, so take my comments for what they are worth. What I've learned is fork oil "weight" is not an exact science like motor oil. You can look online and see charts that'll list the different company's fork oil weight and the viscosity...and there's no rhyme or reason to it. One 10W oil can be totally different in response than another.

Air space is part of the equation for your suspension feel. I have a very rudimentary front suspension. Simple tube with a spring inside. The first time, I filled the forks too far and the front end felt like I was riding on a buckboard. I decided to suck some fluid out of the top of the forks. Not much at all...but what a difference it made.

If you can remove some of the fluid without removing the forks, you might find the additional air space will give you the cushion you need without going to a different fluid.

Chris

 

[dduelin]

ATF does well in basic damping rod forks common to many motorcycles dating from the 1930s. Damping rod forks are still used in some new bikes but newer bikes with better suspensions manufactured in the last 20 years use cartridges in the forks. The former use fixed orifices in the rods to pass fluid under compression and extension. It’s very difficult to fine tune damping rod forks with fixed orifices. Cartridges use metal reeds or petals in stacks to allow progression of damping during compression and rebound. Cartridge forks generally work better out of the box and are easier to tune for individual bike and rider if the stock ride is less than optimal. Honda used Showa fork cartridges in the ST1300. Showa built the ST forks it makes sense to me to start with Showa fluids when tuning them. In my particular case a mixture of Showa SS-7 and SS-8 worked well for me. Staying in brand with fork fluids that have known flow characteristics from the Peter Verdone suspension fluid chart removes the variability of different brands claiming the same weight.

Getting front and rear sag right is a good step toward settling down the ST’s “happy feet” feel. Too little or too much sag on either end affects steering geometry.

 

[dtcoleman]

My 2 cents.
I swapped out bushings, main seals and on my '04 1300. Went with a 50:50 mix of 10w and 5w. Also swapped out OEM progressive fork springs for Traxxion Dynamics OMNI 1.0kg/mm replacements. Big different since I weight 180 lbs.
Along with a Penske racing rear shock the bike handling difference was huge once I got the preload and damping right . . . should've kept the bike.
Dave