Fork oil q's

[red85]

Does anyone know how to change the fork oil on a Lifan 100cc dirt bike. What weight oil should I be using? I'm pretty sure that mine has never been changed so I'd like to put some fresh oil in them. I lost a fork cap awhile ago on a ride and I was surprised that nothing squirted out.

Phil

[forchetto]

SAE 10 or 15 weight depending on how hard you want your damping. Some people get good results from using synthetic ATF (auto transmission fluid). Shops sell special fork oils too. If your forks are a bit old and worn, go for the heavier grades to avoid leakage.

You'll have to strip the front end and withdraw the forks from the machine. Before removal undo the top caps while they are being held by the triple clamps, otherwise it may be difficult to hold them and loosen the top cap later.

Turn upside down over a container, let the oil drain down and pump the fork a few times to get rid of all of it. If you dont know the quantity to put in, measure what comes out in total using a graduated jar, divide by two and add 10cc or so per fork leg to account for what may be left clinging to the insides. Ensure each leg gets the same amount.

[red85]

I went out and got some PJ1 fork oil and the service guy says to mix wix it with a little ATF. Thanks for the help!

Phil

[SpudRider]

Originally Posted by forchetto

SAE 10 or 15 weight depending on how hard you want your damping. Some people get good results from using synthetic ATF (auto transmission fluid). Shops sell special fork oils too. If your forks are a bit old and worn, go for the heavier grades to avoid leakage.

You'll have to strip the front end and withdraw the forks from the machine. Before removal undo the top caps while they are being held by the triple clamps, otherwise it may be difficult to hold them and loosen the top cap later.

Turn upside down over a container, let the oil drain down and pump the fork a few times to get rid of all of it. If you dont know the quantity to put in, measure what comes out in total using a graduated jar, divide by two and add 10cc or so per fork leg to account for what may be left clinging to the insides. Ensure each leg gets the same amount.

Thank you for the superb information, Forchetto! I always enjoy reading your knowledgeable, insightful posts.

Spud

[red85]

Just thought I'd add a little info. In terms of the proper quantity of oil to add during refill, fully compress the fork leg with spring and spacer removed and add oil until it is 100mm from the top. I got this info from a tech at a local shop. I did mine this way since the forks had so little oil in them to begin with and I was unsure what the previous level was to begin with. I made a little tool not unlike a dipstick to get the level right. The ride is 100% better now that there is some oil in those fork legs.

[katoranger]

Good tips. Thanks for reporting back on the results.

Allen

[forchetto]

Originally Posted by red85

Just thought I'd add a little info. In terms of the proper quantity of oil to add during refill, fully compress the fork leg with spring and spacer removed and add oil until it is 100mm from the top. I got this info from a tech at a local shop. I did mine this way since the forks had so little oil in them to begin with and I was unsure what the previous level was to begin with. I made a little tool not unlike a dipstick to get the level right. The ride is 100% better now that there is some oil in those fork legs.

That is a useful rule of thumb to remember. So many folk have no data concerning fork oil quantity, that it should come in useful. Thanks for the advice.

[SpudRider]

Thank you, Red! That is a great tip!

Spud