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Fork Oil


blackhawkxx

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adding in more oil will effect the fork in later stages of compression, too much will run the risks of making the forks almost rigid and easier to blow the oil seals.

I would probably add maybe 5mm or so and try. Motion Pro makes a cool little measuring tool to help make it easier, I have my own little homemade version that I use and does the same thing. Also have oil weights to play with as well if you think that will help. I personally run about 7mm more oil and use a 7.5W oil in my forks. I use a ratio right cup to mix my oil as 7.5 seems impossible to get (5, 10, and 15 are most common in local shops) I like to yank the forks and flush every couple years.

What exactly are you trying to do or solve?

can go with different internals valving and spring rates to suit your needs.

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Plus remember, the standard for measuring the oil level is with the springs removed.

Oil viscosity actually goes down as it ages. So you get a softer suspension as it ages.

Fork rebuild is really not that difficult.

I did the Penske cartridge and spring replacement group buy a few years back. What a difference.

I also did a spring upgrade and race tech gold emulator for the SV. I did it all myself. Really not bad.

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Using additional oil will effectively make the springs more "progressive". Once you install the fork caps, the air trapped in the tubes works like an air spring. Adding more oil will lessen the amount of air, changing its "spring rate". This is usually recommended when trying to prevent bottoming of the fork. Not a bad idea, if you have a lot of deep pot holes in the roads you normally ride, but still no substitute for a proper rate spring.

I always run a little more than standard to help when I'm hard on the brakes at lapping days.

Edited by jon haney
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Plus remember, the standard for measuring the oil level is with the springs removed.

Oil viscosity actually goes down as it ages. So you get a softer suspension as it ages.

Fork rebuild is really not that difficult.

I did the Penske cartridge and spring replacement group buy a few years back. What a difference.

I also did a spring upgrade and race tech gold emulator for the SV. I did it all myself. Really not bad.

Multi weight oil get thinner as it ages due to the break down of the polymers used to thicken the oil as it heats but straight weight oil actually gets thicker as the lighter molecules evap. Fork oil is a straight weight but also doesn't get hot enough for the lighter molecules to evap. Contamination will thicken the oil some.

I run the oil level a little higher than the book says for the injected model in my 98 with 7.5 WT Amsoil full syn fork oil. I found out that the amsoil is the only oil that didn't need to be changed every 10K miles in a 03 Yammy FZ-1 which had to have had the worst problem with bushing wear and oil break down.

Edited by Desert Goat Herder
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One or twice this past year, I bottomed the front which didn't happen in the past. Maybe I just found more dips and bumps but... I have stock weight Honda oil in it that doesn't have that many miles on it. Since I weigh about 175 lbs. without gear, from what I hear, the stock springs should work. I was thinking that it would be a cheap, not too hard of thing to try as long as it didn't make the full travel way firmer.

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From what I recall the front springs are about right for a skinny midget. If your only issue is that it bottomed 1 or 2 times then it may not be worth doing springs, but adding a little oil is cheap and easy.

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Not sure what happened to the pictures... the forum gallery with the attachments seems to have gone away.

But... here's a writeup on doing forks:

http://www.cbr1100xx.org/forums/index.php?showtopic=62937

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