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fork oil weight

19K views 19 replies 9 participants last post by  Beardychops 
#1 ·
I'm a lightweight (120lbs on a good day) and can't decide on which fork oil to use in my upcoming fork overhaul: the standard 10 weight or a lighter 7 weight. Any thoughts? Would the 7W be more appropriate?
 
#2 ·
If I were doing this to mine and keeping the forks stock, I would use 10 wt. fork oil. Having said that, the viscosity does vary more than most realize between brands of fork oil. I would use Motorex brand fork oil if available. If doing mods to the stock forks, I would use the oil wt. recommended by the manufacturer of the mod parts installed, i.e., cartridge immulators, etc. It is my opinion that some riders change the fork oil wt. in the stock forks to try to compensate for the springs being of the wrong rating for their riding weight, and some go the wrong direction by increasing the wt of the fork oil. You should get many opinions on this subject. At your weight (if it were my weight) I would definitely look into getting new rear shocks built to my riding weight...I favor Works Performance products; however, there are other good ones available--the key here is to get them built with the springs for your riding weight. I believe the fork springs are close to what you need for your riding weight as it is my opinion that the manufacturer installs fork springs that are way too light for a 175 lb. rider.
 
#12 ·
Your front tire is NOT in balance, IMHO. If you can't do it yourself, take it to a different shop that uses an old time static balancer.
 
#13 ·
Thanks for all the replys. Another question comes to mind and that is the oil level. I believe it is 106 mm on my 2009 mag wheel bonnie but I know that the previous owner installed progressive springs. How should I adjust the level to suit those springs?
 
#15 ·
My comment is for Matts_Bridge who posted just above my post and another time on the 1st page...he was thinking hie front-end "pogo effect" at a certain speed was due to fork oil.
I should have made it clear who my post was in reply to--sorry to confuse the thread....
 
#16 ·
I don't think it's about balance. I've checked it by myself, in shop and I observed the same effect with two different tyres. It definitely has dependency to road surface. If it's super smooth, there's not pogo. If there's slight imperfections (even new asphalt is pretty coarse with lots of gravel in the mix due studded tyres being used in th winter) I get the effect. With other bikes the same section feels smooth.
 
#17 ·
My bike has the pogo effect. It happened immediately after installing my last set of tires last year. So it is the tires on my bike. But it changed after I changed fork oil. Not as bad as it was with the 10w. So I think it is probably where they overlapped the belts on assembly. You have seen how tires are made I guess? The rubber and belts are laid in by hand then the machine is closed and it is all vulcanized together. Inside out if I remember that part. But it wasn't the fork oil.


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#19 ·
Well one of the bolts tightened okay. The other one would turn as I guess you suspect. So I used a Dewalt electric impact. It got it tight. When I put the fork seals in last year one of them leaked. No leak now. I measured the oil coming out when I drained them and I think I got most of it out doing it that way. But this isn't the proper way.


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