99 rm 125 forks

erklep · Mar 14, 2009

hey all! new to the forum.... been researching for a little bit but first post.

i just bought another project,99 rm 125. i rebuilt the bottom and top ends and a few other things it needed. the fork seals are now leaking. i tried the negative film trick and it didnt work. so last night i pulled the fork tubes and opened them up. replaced the seals and go to add fluid and realize that i have no idea how much to add and where to add it.

can anyone tell me how much fluid to add and where do i put it? do i add it to both chambers or just pour in the one and let it bleed out the holes?

thanks in advance!

Wayne Meuir · Mar 14, 2009

You need to refer to a shop manual for the amount and viscosity . It will be listed in either ML or ounces and will probably be either 10WT, 15WT or 20WT fork oil, some folks use automatic tranny fluid. It may be listed as a measurement from the top of the fork tube, which is the most accurate way to do it. What you do is lift the front wheel off the ground and let the forks extend all the way out, then remove the top caps and pull out the springs. Pour the recommended amount of fork oil in each fork leg right in the top where the spring goes, and then measure down to the oil with the springs removed to see how far down the oil is from the top edge of the fork tube. If it is farther than the book recommends to the oil, add some oil, if it is less than the books recommends, suck some out using a basting syringe or whatever. You can even suck it out with your mouth and a hose if you don't mind a mouthful of oil once in a while (that's a joke, don't really do that). Then reinstall the springs, spacers , or whatever else you took out and then reinstall the caps and you are done.

Good Luck.

Wayne

erklep · Mar 14, 2009

thanks wayne. kinda sorat what im looking for. i understand the whole process and what is involve b/c i have already had them stripped down to install the fork seals. my question is actually how much to add to the inner chamber and how much to add to the outer. the manual only gives me one measurement and im not sure if that is for both chambers or only the outer. i would assume the outer. and im also assuming that for the inner, i can just fill it, put my spring in and bleed it out. and then fill my outers to the reccomended capacity(505ml).

i gave that a shot and it doesnt feel right. it just feels too stiff. like when i hit a landing, im going to be bounced off the bike. but then again, mabye im just used to how soft the leaky forks were b/c they only drained out about 300ml each.

Wayne Meuir · Mar 14, 2009

While I am not totally familair with RM fork design, I have rebuilt a LOT of forks and have never seen one with an inner and outer chamber. Basically, you have an outer fork leg and an inner fork slider,(the part that is connected to the triple trees and moves in and out of the fork lower). When you pour oil into the top of the fork, it actually fills both the inner and the outer legs of the fork becasue it passes through the damping holes in the damping rod or cartridge and flows into the lower leg of the fork. If you don;t ahve a manual you need to get one, you will need it in the future anyway and one repair done by you will pay for the book.

Wayne

99 rm 125 forks

erklep

Wayne Meuir

erklep

Wayne Meuir

Similar Topics

Privacy & Transparency

Privacy & Transparency