250r ATF Fork Oil

[CodyRosa]

Hey guys so I've been using ATF in my forks for awhile now and I love how comfortable it is but on my 250r its a little soft for me (assuming springs are wore as well). I finally found a place close by that sells fork oil and i'd like to stiffen it up just a little bit so what weight could I compare ATF to? 5..10.. so forth..

Thanks!

[yaegerb]

Buy some Bel Ray 20wt and never look back.

[CodyRosa]

Works for me haha.. I'll be heading to my local yamaha dealer tomorrow morning.. i'll see if they have bel ray in stock. Sure hope so! Its 14 bucks a liter there..

[Dirtcrasher]

I believe ATF is close to 10.

All depends on how much you weigh and your style of riding.....

When I was 238lbs even 20 wt with progressive springs was barely enough; I should have run differential 80/90wt. :lol:

[CodyRosa]

Ok then i'll definitely be going to 20wt. lol 80/90wt.. i suppose it could be worth a try =D

How are those progressive springs compared to stock? I'd like to get some soon!

[yaegerb]

I am 255 with 20wt belray and progressive. IMO, You really need to be under 215 or so to enjoy progressive. I will be talking to Milner about what I can do for the front cause I can still compress them easily.

[christph]

I think you will notice heavier weight oil on the rebound damping more than compression damping. If you use oil that is too heavy it will result in packing, i.e., the shocks will not rebound quickly enough before hitting the next bump. If your suspension is too soft, I would correct it with heavier springs and then control the rebound with oil weight. You can also try to stiffen your suspension by filling your forks with more oil (the range is usually specified in the service manual), but this approach is also limited. I've used Progressive springs in a number of my machines and they've always made a considerable improvement.

[barnett468]

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As christph, implied, you don't want to compensate for soft springs by increasing the damping . . Getting the suspension to work PROPERLY, is a balance between oil viscosity AND spring rate.

If you can push on your forks as you sit on the machine and almost bottom them, the springs are obviously too soft even if you only have 5 wt oil in it.

To quickly and easily increase the spring rate in your case for the time being, you can either add around 8 - 10 psi of air to your forks if someone added valves to them, or you can get some pvc pipe or metal pipe from the hardware store that just fits inside the fork tube, and cut it 1" long and put that on top of the springs . . Doing this will also increase the front ride height by 1".

As far as oil goes, if you weigh under around 180, I would definitely not use anything higher than 15 wt . . The stock viscosity for your bike is ATF, which is 7 - 8 wt . . If you go to 15, you are DOUBLING, the viscosity, and even with some wear, it is still a big jump and will definitely be noticeable . . Also, increasing the oil viscosity increases the harshness more than increasing the spring rate will.

If your bike is an 85, you can also increase the oil level from the factory setting of 7.3", to a level of 6.3 - 6.5" . . This will make them firmer near the end of the stroke but will have little affect in the beginning of the stroke, and will only provide a minor increase in spring resistance.
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[barnett468]

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I believe ATF is close to 10.


Auto trans oil viscosity varies from around 7 – 8 at 70 degrees depending on the type . . The chart below is DEXRON III which is non synthetic . . The oil is well over 100 degrees after only a few minutes of riding in mild to hot temps.


................................Http://www.viscopedia.com/fileadmin/_processed_/csm_Graph_Oil_LM_ATF_III_1024_6a3a6f96ad.png
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[barnett468]

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Basically, it's reasonable to assume your springs are orig and most likely sagged out at least 1/2" . . Based on your description, if you weigh under around 200 lbs, and are not a professional racer, I would do the following and see how you like it:

15 wt oil

If it is an 85, fill the tubes to 6. 25" from the top with the springs out and forks compressed . . If it is newer, fill to 4" from the top.

You must stroke the forks a few times after filling to insure there is no air trapped, otherwise, your measurement will not be correct.

Ride the bike . . If it's still a little soft, which I'm going to guess it will be, then install the 1" spacer . . You can always shorten the spacer if its too much.
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[arlaunch]

Very useful information.

Thanks

[CodyRosa]

Ok so i got to ride my R for the first time today.. over woops it is very very comfortable.. i love it. What I hate is when I sit on it it sags down a few inches.. which is understandable.. im sitting on it ( Almost feels like the back sits higher than the front)but when I get off it goes up like an inch or 2 and i can pull on the bars and the front raises quite a bit. I weigh 175. Last year I did add PVC and it did help a bit.. but I forgot where I put them at! I'm guessing the progressive springs is what i'd be looking at then?

[yaegerb]

So I had a very good conversation with Milner (onfurmula1). I highly suggest you have a chat with him before you spend 100 on progressive springs. He's a wealth of suspension info.

[oile]

I 2nd Milner he knows his stuff about forks and rear shocks. He's building me an set of forks right now for TT track.

[CodyRosa]

Alright i shall do that! Thanks guys

[barnett468]

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Ok so i got to ride my R for the first time today.. over woops it is very very comfortable.. i love it. What I hate is when I sit on it it sags down a few inches.. which is understandable.. im sitting on it ( Almost feels like the back sits higher than the front)but when I get off it goes up like an inch or 2 and i can pull on the bars and the front raises quite a bit. I weigh 175. Last year I did add PVC and it did help a bit.. but I forgot where I put them at! I'm guessing the progressive springs is what i'd be looking at then?

How long was the PVC?

Why did you remove it?

4 feet of 3/4” PVC is around $2.00 . . 4 feet of 3/4” fork spring is around $130.00


FORK AIR

If I were you, before you do anything, I would first put some air in the forks as I previously suggested and try that unless you prefer not to run air, in which case I would get the new springs which is really less hassle in the long run.

If you try the air, I would reinstall the spacers you removed first . . This way you can use less air which is better.

Your bike should have an air valve in the top nut and look just like this.

http://images.cmsnl.com/img/products/bolt-assyfrfork_medium51450ME5003-01_4e93.jpg


SPRINGS

Based on your description, you definitely don’t want progressive springs for your app . . I would think the .48 kg springs from Race Tech would be near ideal, and many people run them . . You can call them and they will give you their suggestion but sometimes, they suggest rates that are a bit stiffer than necessary, however, they have an enormous amount of experience in this area because they sell a lot of springs and get a lot of feedback from their buyers that have bikes just like yours, therefore I would trust their opinion far more than most others, simply because they will have a good overall consensus from many people instead of just a few, but certainly call some other places too if you want before you decide.

Since you are not bottoming now, and you like the overall feel of the suspension and basically just want to raise it up, there is no need for really stiff springs, and in fact, you could run a 1 1/2” spacer providing your springs won’t coil bind . . This would basically increase your ride height without increasing your spring rate so it will remain nice and comfy, however, it will increase the amount of resistance the spring has at full travel by approximately 40 – 50 lbs which will make it more resistant to bottoming.

If you want to calculate the amount of space your springs have at full compression, simply do the following:

Measure the space between two coils with a feeler gauge.

Count the number of spaces.

Multiply the number of spaces by the amount of space between the coils.

Measure the amount of preload.

Add the preload number to the amount of travel the forks have, which in your case is 9.84” . . The Tecate had

Subtract the amount of travel from the amount of space between the coils.

The final number will be the amount of space you have left.

You “can” add a spacer that is up to within 1” of the remaining number . . In other words, if the final number you have is 2”, you can add a spacer that is 1” long or less . . If the final number is 3”, you can add a spacer that is 2” long or less.

This being said, If it sags 2” under its own weight, and another 2” when you sit on it, Your springs really are too weak providing that no one has shortened them before.



FORK OIL

You definitely do not want fork oil much heavier than you already have, and it would be best to start off with the same viscosity of fork oil you have in them . . If you do not know what oil you have, and you change the oil, you can start with the factory viscosity which is 7, or you can just try 10 instead.


FORK SPRING OPTIONS

http://racetech.com/ProductSearch/3/Honda/ATC250R/1981-85


CONTACT INFO

http://www.racetech.com/page/id/18
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