 Fork Oil Question
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Joined: Feb 2009
Posts: 246
Adjunct
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OP
Adjunct
Joined: Feb 2009
Posts: 246 |
My front forks are too springy for my liking. I'm going to replace the stock springs with the Ikon Progressive fork springs. According to my service manual the stock fork oil is 10w. I see Motul also sells a 15w. I was wondering what other members have used. Probably going to just order the 10w unless someone can give me a reason why the 15w is better. Should I also assume 1 liter is enough for the swap out?
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Re: Fork Oil Question
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Joined: Sep 2007
Posts: 1,668
Learned Hand
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Learned Hand
Joined: Sep 2007
Posts: 1,668 |
10w is way too thin. 15w may work for you. It's too thin for me, and i'm only 200 pounds. Even with Ikon springs it will bottom hard on hard braking or medium sized potholes. I'm gonna change to 20w when i get the time. One bottle is enough.
Howbeit when He, the Spirit of truth, is come; He will guide you in all truth:
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Re: Fork Oil Question
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Joined: May 2007
Posts: 5,068 Likes: 1
Saddle Sore
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Saddle Sore
Joined: May 2007
Posts: 5,068 Likes: 1 |
The combination of the tight initial wind on those springs in conjuction with 10W oil will just about guarantee you'll bottom out big time . Some folks experiment with a blend of 15 and 20 to get it right . Depends on a lot - weight , comfort level , etc .
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Re: Fork Oil Question
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Joined: May 2006
Posts: 3,971
Loquacious
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Loquacious
Joined: May 2006
Posts: 3,971 |
Just for the fun of it -- proper damping would be shown by pushing the forks down a few times as far as one can in quick succession, and have them rise to no more than their original height. The speed at which they rise is another factor, yet a might difficult for me to describe in words. The best I can say is the desired ascension rate is slightly slower than what one would witness if no oil was in the fork tubes. I know that is a might vague in words. In that we have no front fork damping adjustment besides spring rate & viscosity,  trial and error is our method. At my weight of 240 lbs, I'm going to try 15 or 20 weight next time. I'm running 12 weight now. With around 15K miles on the fork oil, it's either worn out or way too light, as my forks rebound much higher than their resting spot.
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Re: Fork Oil Question
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Joined: Jan 2005
Posts: 12,877
Should be Riding
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Should be Riding
Joined: Jan 2005
Posts: 12,877 |
Benny
Black & Silver '02
Too many mods to list
Not enough miles ridden
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Re: Fork Oil Question
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Joined: Jan 2005
Posts: 4,932 Likes: 2
Loquacious
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Loquacious
Joined: Jan 2005
Posts: 4,932 Likes: 2 |
we should do this every weekend!
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Re: Fork Oil Question
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Joined: Feb 2009
Posts: 246
Adjunct
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OP
Adjunct
Joined: Feb 2009
Posts: 246 |
That is super helpful. I'm 250 lbs and ride on some pretty crappy roads. I think I'm going to go for the 20w and see how it works out.
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Re: Fork Oil Question
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Joined: Sep 2007
Posts: 1,668
Learned Hand
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Learned Hand
Joined: Sep 2007
Posts: 1,668 |
Quote:
With around 15K miles on the fork oil, it's either worn out or way too light, as my forks rebound much higher than their resting spot.
In my case, i changed the springs only and rode it like that for 6-8 months. It felt great, but then i upgraded to dual brakes which required changing the fork leg, so i had to change the fork oil. It hasn't felt right since then. Apparently, after 40,000 miles, the stock 10w oil had become rather thick ...apparently more like a 20w or heavier. I only know that it never bottomed out before, and rode fine. Maybe changing fork oil as maintenance is overrated?
Howbeit when He, the Spirit of truth, is come; He will guide you in all truth:
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Re: Fork Oil Question
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Joined: Jul 2007
Posts: 96
Member
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Member
Joined: Jul 2007
Posts: 96 |
I changed mine yesterday and went to 15w. you will need about 520ml per side, so divide your 1 litre bottle in half before you start and use the extra 20 ml from wot you pour out of the forks after it has had a chance to settle. Fill the forks to 166mm down from the top with the spring out and the fork compressed. 
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Re: Fork Oil Question
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Joined: Jan 2005
Posts: 18,825
"Lighten up, Francis."
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"Lighten up, Francis."
Joined: Jan 2005
Posts: 18,825 |
12.5W seems to work fine for me.
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Re: Fork Oil Question
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Joined: Apr 2005
Posts: 582
Adjunct
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Adjunct
Joined: Apr 2005
Posts: 582 |
I found 20w way too stiff it was like riding a solid fork, granted I tip the scales at 190 or so. I run Bel-ray 15w & I'm pretty happy. I want to see if Race Tech make gold valve emulators to fit our bikes see if I can get better performance from the front.
"Got the wind in my face the road goes on for miles...."
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Re: Fork Oil Question
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Joined: Jul 2007
Posts: 234
Adjunct
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Adjunct
Joined: Jul 2007
Posts: 234 |
When oils ain't oils... Be careful of the oil you chose. The weight spec of oils is fairly broad. Go to Motul Viscosity Chart They have a good indication of the viscosity of fork oils at the bottom of the chart. The Kayaba G10 oil as specified in the Triumph manual has a Viscosity of 37.5 @40C. Motul 10W is 35.9 so just changing brands has you 4% softer. I installed progressive front springs and decided to go 20% higher than stock fork oil (Viscosity of 45) so thats a 50/50 blend of Motul 10w and 15w. I'm 200 lbs and that worked for me.
Adventure before Dementia...
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