My front end is too soft and I get too much front end dive also would like to change.my rear oil in my shocks. I have a Mityvac I can use so can i use that to ADD oil to my front forks from the bottom drain hole that way I don't have to mess with the top? Also can I keep the rear shocks on the bike and suck oil out with the mityvac? I know I can add oil to the rear with it but can I suck it out on the bike?

 

I'd like to know too....on the rear shocks. I have a set of 13" take offs that I plan on changing but I'd like to change the oil first..

 

Casper

If your shocks are off then yes by all means use a mityvac to suck out the old oil upside down. I just wanted to know if I could get away with keeping them on the bike and suck out the oil to save removing them.

 

I would think,you would still have to have the top vented to let the air out,I might be miss understanding you about having to remove the forks to change oil in them

 

Rear shocks.
You've got to remove them and turn them over in order to use the vacuum pump to suck the oil out. Pulling a vacuum from the top will not cause the oil to rise up and out. You might get some out that way, but by no means all of it.

Front forks.
Draining without removing the cap will be tedious as vacuum in the fork tube will hold the oil back. It will drain, but will take longer. You can pull it out with the vacuum pump and catch can, you'll need to cycle it several times in order to do the job.

As for filling that way, it could be done, in theory. You're going to need a larger catch can, and I'm not 100% certain you can sustain enough vacuum in the fork tube to pull all the oil up in one pass. Doing a second pass would be neigh to impossible. You'll have to be quick with the screw when you disconnect the line from the fork tube, so as to not lose much oil.

I really thought about it myself (04 RK), but ultimately went from the top. Even went so far as to buy the fittings for a metal can I have.

 

I was able to fill the front forks of my '96 cop bike with the mighty vac, but it had air suspension. Maybe you can figure another way to hook it up. I removed the schreader valve from the fill port, adapted the vac, pulled the drain plug and measured what came out.I pumped the forks a few times to get it all out. Filled a container with the same amount, adapted a hose and shut off valve to the drain hole. With the valve closed,then pumped the vac to about 10 lbs. Opened the valve with the end in the new oil, and the oil was sucked up into the fork. Did the same to the other fork. 10 minutes a fork. I've done shocks before but they have to come off the bike and be turned upside down. It can get sloppy, but here's what I did. I used a small plastic tube like one hat comes with carb cleaner, and used compressed air from a can of keyboard cleaner. When turned upside down ,sprayed the air into the shock. I did this in a bucket so I could collect and measure how much came out. Why?, because there's no mention in the manual about how much oil each shock holds. I used a meat syringe to refill the shock, but you could do it with the vac if you have enough adapters and a couple of shut off valves. Like what you would use on a fishtank line.,,

 

Do yourself a huge favor and change the oil in those forks. Showa forks come with some pretty nasty cat urine in them and changing it out is the only cure.
On the forks, take the few extra steps to allow pouring the oil in from the top. And don't try to pour it all in at once - pour about half in and stroke the forks, the pour in the rest. I've had good results with HD Type 'E', as well as 10 wt Bel Ray and Maxima.
The manual says 10.8 oz. (per leg) but I put in 11 oz. whenever I use 'E' or 10 wt. - works very well.
I always replace the PITA air assist shocks with regular shocks. But there are threads on this forum that explain rear shock oil changing - some with pics.

 

Thanks guys for the ideas. Now when you add half oil to front forks then stroke.the shock are you putting the cap.back on and bike on ground front brake.on? Then bike back on jack cap off oil in? Seems like alot of steps that involve up and off a jack that I hate.

 

Fwiw, I did not stroke the forks on my 04 RK. I looked at the design and how the oil moves in them, and could see that it should do a fine job of flowing through and getting down to the bottom of the forks. I filled slowly with a funnel, and was done. 12 oz as I recall (RK takes a different amount).

Not guaranteeing you'll get the same results from not stroking the forks, but I don't know of any reason you inherently need to stroke them to move the oil down the fork tubes.

 

Sorry, I have a lift table and the stroking part is never a problem (he-he).
You could lower the bike enough to make decent tire contact without removing your bike from the lift - then jack it back up.
A full stroke is not necessary (just up and down a couple of times) and if done slowly the oil should not burp out the top. I usually go on and thread the cap on maybe one or two threads anyway.
If you pour slowly and wait a minute between pours, you may not need to stroke the forks at all. Thing is though, once the oil burps out the top you're starting all over again (draining, etc.) since it's impossible to tell exactly how much was spilled.