replace fork oil from the bottom up

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manxman

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Jun 17, 2015
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I got tired of waiting for new fork oil to dribble down around the spring. It seemed to take forever for enough air to work its way up to make room for the oil. And some oil inevitably made a mess over the triple clamp and tank. So last time I put the new oil in from the bottom up using a syringe.

You need a 60 cc syringe with a tapered adapter. They are widely used in hospitals... you don't want to know what for. if you have a nurse friend she can pinch you one. They are disposable so it's a small crime. Or a veterinarian would likely sell you one. Also a pencil and a lot of rags. Fill a bowl with 160cc 20W fork oil. (10cc extra for spillage)

Do one side at a time and you won't have to worry about the bike falling on its face with the springs sticking out of the top like rabbit ears. Don't ask me how I know.

Drain all the old oil by pumping the forks. Unscrew the big top fork nut to allow air to get in. Screw the plastic adapter in the drain hole. Fill the syringe from the bowl and lock it onto the adapter. After injecting the oil, plug the adapter with the pencil point. Repeat. Replace drain screw. Clean up the mess.

It seemed to be faster and less messy than the top down method. There was no fluid lock because the air was already in the right place from the get go..

Manxman
 
I do mine from the top with a syringe and it takes just minutes. I extend the spring about an inch and inject the oil into the center of the spring and it just goes in without any mess. From the bottom seems a bit backwards, with gravity and all.
 
All of us have wanted to bottom fill quickly w/o waiting for bubble to work up against the down flow, like good brake shops do but > for questing how much to compensate over fill to make up for the leak out between removing filling pump and getting plugs started and sealed. Please reveal your insight innovation on this as can not imagine a pencil plug or small screw in tube hanging out while riding.

I have gotten as far as removing the fill adapter but lost enough fluid on next step gave up back to cattle size syringe as funnel hung over the fork leg while i did something else usefull in mean time. In Peel I made two holes in Alu fork caps and groove under caps so spring washer not blocking holes so can squit in fluid still fairly slow to allow baby to burp a bit in intervals but gets dang close to measured amount inside w/o too much it hydrolocks in drive way nor not enough to loss the non linear air spring rough riders come to appreciate in the old fashioned forks only hobot could love over all others. Its a non issue if not bottoming or topping out on normal surfaces but there is only a dozen or so ml differences in my top offs to avoid lock up or fail to give last vital 1/4 inch crash down cushioning.
 
Guido said:
I do mine from the top with a syringe and it takes just minutes. I extend the spring about an inch and inject the oil into the center of the spring and it just goes in without any mess. From the bottom seems a bit backwards, with gravity and all.
Click to expand...

Hi Guido.
This is how I fill my forks too (except forcthe drain screws there is no need to grovel near the floor).
Manxman: :evil: "...small crime..." :evil: Go to a pharmacy and buy a syringe! They usualy stock most sizes.
Ta.
 
just borrow your wife's turkey baster when she's gone for a while and fill it from the top

why not? you use her toothbrush to clean the oil stains around the head.......
 
I have never had problems with filling my forks from the top, I use a messure cup and a small funnel to fill mine and only takes a few minutes to do each side, seems like more hassels doing it from the bottom.

Ashley
 
Beer makes human urinary bladders fill from the bottom up and then have to empty from bottom first, in about same time as elephants to mice full of beer do too. Real men and bartenders should be able to pour a stout beer or start their cycles w/o a devices aid. Fork plugs are tricky for me to start very easy.
 
needing said:
Guido said:
I do mine from the top with a syringe and it takes just minutes. I extend the spring about an inch and inject the oil into the center of the spring and it just goes in without any mess. From the bottom seems a bit backwards, with gravity and all.
Click to expand...

Hi Guido.
This is how I fill my forks too (except forcthe drain screws there is no need to grovel near the floor).
Manxman: :evil: "...small crime..." :evil: Go to a pharmacy and buy a syringe! They usualy stock most sizes.
Ta.
Click to expand...

I couldn't get a large (60ml) syringe from my local drug store. They had small syringes (1 - 10ml) which are used for injecting medications. Big ones aren't used for medication, they're used for patient care jobs like irrigating catheters, etc. The hospital is the only place I've found them. Engine fluids and brake fluid are really hard on the rubber plunger so I clean mine out with brake parts cleaner, spray it with silicone lubricant and store it disassemble for the next job. It gets used more than a lot of tools in the workshop.

If your friendly paramedic or nurse is sourcing one, try get a check valve as well. They are used in some IV setups. The perfect thing for bleeding brakes.

And IV tubing is the perfect thing for balancing carbs. It's smaller diameter than the 1/4" vinyl tubing from the building supply or aquarium store. Filled with ATF, it is nicely dampened so the fluid level doesn't bounce around at slow idle.
 
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