Changing Forks oil? Really!

[GeorgeSK]

As usual, Oyabun, nicely explained. Your points about wear due to loading not being completely axial (thus letting internal metal on metal contact, albeit lubricated, to occur) never occurred to me. Of course I'm not a mechanical engineer or racing aficionado, so I guess I never really thought about it too deeply.

[easyrider]

The question remains.. At what interval?? Mileage , years, environment, etc etc . Nothing lasts forever but 20,000, miles , 10,000 miles, .. I don't think HONDA has a routine maintenance program for fork oil. ??Some think when the seals leak its time to do it all. Oils of today account for many of the wear and chemical maladies encountered in a motorcycle fork and are much more durable chemically than ever before. Just wonder why its not a maintenance item or why drains are not provided on all bikes.

[Oyabun]

The question remains.. At what interval?? Mileage , years, environment, etc etc . Nothing lasts forever but 20,000, miles , 10,000 miles, .. I don't think HONDA has a routine maintenance program for fork oil. ??Some think when the seals leak its time to do it all. Oils of today account for many of the wear and chemical maladies encountered in a motorcycle fork and are much more durable chemically than ever before. Just wonder why its not a maintenance item or why drains are not provided on all bikes.

I'd definitely change fork oil before seals start to leak.
Given the fact that the PCX has no sliding bushes in the forks, only the fork fluid provides lubrication, I'd change them every four years or 20k kms whichever comes first.

As for why no oil drains on the forks there's no definitive answer, but I'd surmise there are many reasons. First is clearly cost. Every penny saved on an item sold in tens of thousands saves a lot. Also even if a drain provided, most fork internals are such, that one cannot remove the old fluid properly without cycling the fork and setting it upside down - which anyway means that the forks have to be removed from the bike and springs deinstalled to be able to cycle the fork through its stroke. Third, most of the bikes doesn't allow refilling of the forks without removing them, so why bother with a drain?

[easyrider]

No removal here ?? Some do and some don't ??


https://www.youtube.com/watch?v=OpHpPuFMV1o

[Oyabun]

No removal here ?? Some do and some don't ??

I know that video, and it's great that you've linked it here.
As it is a perfect representation of how not to do a fork oil change.
First of all, he had to support and raise the bike, remove all fairings, front brakes, axle, fender and wheel and still made a complete mess - and this was even the smaller problem.
By keeping the forks in place, and not cycling them through their stroke, and not cleaned them, I guarantee that at least a 50ml of the most contaminated fluid had left in the damper od assembly or even more in the cartridge as these are not self draining. And to make it even worst, not only that the left in fluid will degrade the new one immediately, he misses on the quantity also. Fork fluid quantities are an approximate indication of how much you have to buy, but the measurement should be the fluid level measured on a collapsed fork without the spring inserted. It is important, as fluids are not compressible, and remaining air acts as a secondary air spring when the forks are close to be fully compressed. Leaving fluid in the forks from the previous volume and thus overfilling the forks not only lead to shorter mechanical life due to increased wear, but also result in harsh unpleasant suspension action and early death of fork seals due overpressure.

In reality he could manage the fork oil change without removing the fairings and could have been able to done it properly of he would loosen the two pinch bolts on the triple and simply slide the fork legs out after removing the wheel. Would have managed it much cleaner also.

Now think about this on the PCX. No access to the fork legs from above, fork caps held in place by a fork cap what is held in place by a circlip and preload pressure from the spring. Imagine opening the oil drain on the fork only to contaminate everything with fork fluid, wrestle the fork cap out of it's place without place, fill in the proper amount of fluid, measure to the correct level, and reassemble everything. Will probably if you're a gynecologist used to work in tight and messy spaces, but pretty much everybody else would probably end up removing the forks anyway.

As a conclusion probably earlier, very simple forks on naked bikes without fairings might be feasible to do without removal - but even then the draining would be only partial - but more time and effort is wasted on a modern bike to make a sub standard work by not removing the forks.