February 9, 201016 yr After some help. Had to change the fork seals on my 09 sherco and ever since i did the forks are rubbish. The front end feels heavy and difficult to bounce around. I put 330ml of motorex oil in each leg. Any advice on why they are so rubbish. The bike is basically brand new, a few (3 trials). Thanks in advance for the help!
February 9, 201016 yr I'm fairly sure you will have put far to much oil in the fork leg, there's a damping rod in the right fork leg that will still be full of oil, you'll have to take it out to drain it properly and it takes a while to get the majority of it out, I don't think you will ever get it all out. When refilling it's better to use the specified oil height measurement then it doesn't matter if you get all the old oil out. Oil level on right leg: 60mm With forks at bottom Qty 370cc Oil level on left leg: 110mm With forks at bottom and without spring Qty 385cc
February 9, 201016 yr Author Thanks for that. i forgot to mention that it is 5 weight oil. is this correct or should it be 4?
February 9, 201016 yr 5wt is fine, the factory spec 4wt but there is only one or two company's who make that grade and there not the ones recommended by the factory so I wouldn't be surprised if it was just another miss print.
February 10, 201016 yr Aside from the proper quantities, you MUST extract the hydro unit from the right fork and pump it untill ALL the old oil is out or else things will be off!
February 10, 201016 yr As a rule of thumb, I always measure what I drain out so as to only refill with the same amount (unless the fork seal was a massive leak) Also, to make sure the forks are not binding, re-tighten the fender bracket and the front axle pinch bolts with the front forks compressed.
February 12, 201016 yr Author I know some say it doesnt matter if 4 or 5 weight oil, but if the number refers to viscosity then going from 4 to 5 weight is a 25% increase. Surely that alone would effect the fork action. I did some maths and gave a value to each ml of oil going in each fork. Lets say that for each ml of 4 weight oil is given a value of 4 then the Right leg has a value of 1480 and the Left leg has a value of 1540. If the forks were filled with 5 weight and the same rule (but each ml = 5) applied then Right leg has a value of 1850 and the Left leg has a value of 1925! A table may help Right 370ml fork 4 weight = 1480 5 weight = 1850 Left 385 ml fork 4 weight = 1540 5 weight = 1925 Surely this will make a difference! To get around this problem perhaps it is best to mix 5 weight and 2.5 weight of the brand of oil Sherco recommend! If so then this is how it works out. For the right 5 weight 222 mls 2.5 weight 148 mls For the left 5 weight 231 mls 2.5 weight 154 mls Then same volume and same viscosity. Or have i sat up all night thinking for nothing?? Edited February 12, 201016 yr by sdeane01
February 13, 201016 yr I know some say it doesnt matter if 4 or 5 weight oil, but if the number refers to viscosity then going from 4 to 5 weight is a 25% increase. Surely that alone would effect the fork action. I did some maths and gave a value to each ml of oil going in each fork. Lets say that for each ml of 4 weight oil is given a value of 4 then the Right leg has a value of 1480 and the Left leg has a value of 1540. If the forks were filled with 5 weight and the same rule (but each ml = 5) applied then Right leg has a value of 1850 and the Left leg has a value of 1925! A table may help Right 370ml fork 4 weight = 1480 5 weight = 1850 Left 385 ml fork 4 weight = 1540 5 weight = 1925 Surely this will make a difference! To get around this problem perhaps it is best to mix 5 weight and 2.5 weight of the brand of oil Sherco recommend! If so then this is how it works out. For the right 5 weight 222 mls 2.5 weight 148 mls For the left 5 weight 231 mls 2.5 weight 154 mls Then same volume and same viscosity. Or have i sat up all night thinking for nothing?? You can do a bit of blending if you like, but I have never known anyone that could tell any difference in 4 vs 5 wt. Seems everyone just uses 5 wt, unless some heavier rider may want something with more vis like 7.5 or 10!
February 15, 201016 yr I know some say it doesnt matter if 4 or 5 weight oil, but if the number refers to viscosity then going from 4 to 5 weight is a 25% increase. Surely that alone would effect the fork action. I did some maths and gave a value to each ml of oil going in each fork. Lets say that for each ml of 4 weight oil is given a value of 4 then the Right leg has a value of 1480 and the Left leg has a value of 1540. If the forks were filled with 5 weight and the same rule (but each ml = 5) applied then Right leg has a value of 1850 and the Left leg has a value of 1925! A table may help Right 370ml fork 4 weight = 1480 5 weight = 1850 Left 385 ml fork 4 weight = 1540 5 weight = 1925 Surely this will make a difference! To get around this problem perhaps it is best to mix 5 weight and 2.5 weight of the brand of oil Sherco recommend! If so then this is how it works out. For the right 5 weight 222 mls 2.5 weight 148 mls For the left 5 weight 231 mls 2.5 weight 154 mls Then same volume and same viscosity. Or have i sat up all night thinking for nothing??
February 15, 201016 yr I know some say it doesnt matter if 4 or 5 weight oil, but if the number refers to viscosity then going from 4 to 5 weight is a 25% increase. Surely that alone would effect the fork action. I did some maths and gave a value to each ml of oil going in each fork. Lets say that for each ml of 4 weight oil is given a value of 4 then the Right leg has a value of 1480 and the Left leg has a value of 1540. If the forks were filled with 5 weight and the same rule (but each ml = 5) applied then Right leg has a value of 1850 and the Left leg has a value of 1925! A table may help Right 370ml fork 4 weight = 1480 5 weight = 1850 Left 385 ml fork 4 weight = 1540 5 weight = 1925 Surely this will make a difference! To get around this problem perhaps it is best to mix 5 weight and 2.5 weight of the brand of oil Sherco recommend! If so then this is how it works out. For the right 5 weight 222 mls 2.5 weight 148 mls For the left 5 weight 231 mls 2.5 weight 154 mls Then same volume and same viscosity. Or have i sat up all night thinking for nothing?? Interesting....give it a try and let us know.
February 16, 201016 yr I have just switched from 3w to 5w and it is a BIG difference Could not get any change using the clickers with 3w (too little compression and too fast on the rebound) so switched to 5w and got the clicker so I like it in a middle setting......so if your clicker is on either end of the spectrum you can slightly change the oil weight either way to get a effect ...it is subtle and takes a good "feel" My oil level is as mentioned in above post...I will only do it by measured oil height and never ever by volume
February 16, 201016 yr Had a Montesa once and it took 10wt but my local dealer only had 2.5wt, so I put that in then the rebound and damping adjusters failed to respond...I would have been better off pouring vinegar in.
February 16, 201016 yr ..I would have been better off pouring vinegar in. Would have been cheaper as well.
April 10, 201016 yr I've just changed the oil on my 2009 Racing Sherco and now the front end is awfull. I refilled both legs with 330ml. Should I be measuring 60mm on the right leg from the top? Surely when the suspension is fully compressed (more than 60mm) the damper will go solid because the oil can not be compressed.
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