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Discussion Starter · #1 ·
Several reasons. Inevitably, 'some' moisture/condensation gets in. However, most of it is fine metal particles. Ever notice how used fork springs are so shiny and polished where they contact the tubes? That is from the oxide layer on the outside of the spring coils being polished off by suspension action. Where do those oxides go? Yup, into the oil, where they work as tiny little cutting tools. But what if the springs were polished when first installed? The fork springs below are brand new - Progressive springs for a Yamaha XJ650. The lower is new, the upper is polished. Easy to do.

What I did was make a mandrel to fit inside the springs (5/8" wooden dowel and wood screw), wrapped with masking tape for a snug fit. Then, I chucked the mandrel into a drill and used it to spin the spings while holding ScotchBrite around the springs. Worked the entire length of the spring. Followed up with (wet) 2000 grit wet or dry around them. Finished by using dry crocus cloth. Essentially a mirror finish and now there will be far less gunk to cause abrasion and wear in the forks.

Took all of 30 minutes.

Automotive tire Coil spring Auto part Metal Automotive wheel system

Tool Gas Drill Auto part Wood
 
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· Moderating: Fair & Just
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Great info!
Would this then be a one-time procedure? or
Something you would do at every fork oil change?
 

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Discussion Starter · #3 ·
Just a one-time procedure at the install of new springs. But, if used springs are not polished, this can be done easily enough. One other tihng is flushing the forks. After draining the gunky oil, I fill the forks with cleaning solvent and cycle them through their stroke several times, then let them sit. I have the triples off, so inverting the forks and draining the solvent out was easy. This is much easier on Gen1s, as they have fork drain holes. Still, if the front wheel is off, it's easy enough to pull the tubes, drain, flush and refill them. This came to mind when I read your wearing out the forks thread.
 
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my take on this is. dirty fork oil is due to lack of oil changes basically ask the average owner/rider when they last changed the fork oil and you will either get a blank look or perhaps "when I had a leaking oil seal a few years back".
reason being it's so much hassle to strip the front end down to do it. while the above procedure may reduce one element of contamination (from the springs) it will not reduce the contamination from all the other fork components like bushes aluminium plungers (purposely made of soft material so it wears) and generally all other contaminants like water (from condensation) and so on.
in my view the best alternative is to fit drain plugs in the lower fork (like as stock on gen1's) easy to do on gen 2's as the undrilled position is right there (unused) m5 bolt and copper washer makes a perfect drain.
then once a year (or when you do the engine oil change, drain the forks and refill. you will always have clean (ish) oil in the forks. and most likely less fork wear also.
 

· Moderating: Fair & Just
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If anyone wanted to change their fork oil once a year, I would not hold that against them. You cannot overdo it. I just don't understand the whoopla about putting a drain plug at the bottom of the fork. What's the big deal about dumping it out the top of the fork?
 

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What's the big deal about dumping it out the top of the fork?
nothing only time and effort, if your fine with that super, but the easier it is the more likely you are to do it.
I can change the oil on both forks at the same time in 10/15 mins, and have done on the gen 2 while experimenting with different oil densities, support the engine with blocks of wood, remove drain plugs, while the oil is draining remove the 4 hex bolts from the bars (not required on ER forks) compress the end plugs, remove the circlip, take out the plugs. withdraw the springs and wipe down, by this time the oil is drained, replace the drain screws, compress the forks by lifting the front wheel, fill with oil to correct level, extend the forks, replace springs and plugs refit handlebar screws, done. don't forget to remove the engine support and work the forks a couple of times before riding.
 

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This an the other threads regarding fork oil change is just like all other maintenance stuff. Every 2 years for me is my schedule for non engine oils. Brake fluid, coolant, fork oil and blinker fluid.

When was the last time you completely flushed your brake system? Even on your car, those in wet climates know that this is a must on anything that uses hygroscopic oils. Not saying fork oil is hygroscopic just is on the same schedule.

To me seeing the way the seals are when I used to park out doors 24/7 and ride 365 days 2 wheels only, it was nothing to question insect bodies that got on the fork tubes and water intrusion it was just reasonable to clean it out. I have never done the drain thing as I was always concerned about not getting the levels even so I remove and when refilling after reassembly would measure to insure evenness. Last rebuild (this bikes first) I added Motorkote to it. With the fork tube compressed I measure it at 5 inches. Every year I do the change out whether it was ATF or Fork oil it always was discolored, I really do not see what polishing the spring would benefit other than making sure it is clean, I do this in a parts washer now days.
 

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I have never done the drain thing as I was always concerned about not getting the levels even
easy, over fill the tubes with a measured amount of whatever fluid your using by 10ml or so (for arguments sake lets say 400ml) then suck out the extra fluid with a Turkey baster marked at the correct measurement for your forks.
 
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