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Fork oil top-up?

Joined Jan 2019
101 Posts | 10+
Toronto
My right fork leg seal was leaking, which I managed to stop by using a homemade Seal Mate. In the process of pulling out the dirt from the seal, a LOT of fork oil seeped out. That's in addition to what's been dripping out since I bought it, as well as when the previous owner stored it (seems to only leak when it's not ridden). Is it possible to just top up the fork oil by removing the cap with the fork in place and just adding to a certain air gap, or do I have to remove the leg, dump out everything, and measure the 524 cc (right leg - Low Seat)? Lastly, the owner's manual lists SHELL Advance Fork 7.5 or Donax TA - the current oil is red in colour, so would that be the Shell or the Donax, or does it matter as long as I just top it off with anything 7.5 weight?
 
You can use Spectro 7.5W as it's similar viscosity.

What you can do is lift the front end of the bike up so the wheel is off the ground and take both caps off. Measure the distance to the oil on the non-leaking leg, and duplicate that on the leaky leg. It might be tricky depending on how the fork is assembled, and might not work if it's a cartridge type.

The air gap is measured with the fork fully collapsed, no spring installed, so you can't do it that way without taking it all apart. Depending on your mileage, that might be a good thing to do anyway though.
 
Thanks. I'm at 18000 kms on the completely stock setup so I'll give that a try. I want to put off a full rebuild for when I upgrade the forks. The oil that seeped out looked practically new, so I'm pretty sure it's still fine.
 
You'd be surprised how nasty it gets really fast just from the spring scraping the inside of the tube. Lots of metal buildup.
 
From memory when I changed my fork oil, there is different amounts in each leg.
Mine was also overfilled from the factory. mine is the low version and had the standard bikes amount of oil in them.
 

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From memory when I changed my fork oil, there is different amounts in each leg.
Mine was also overfilled from the factory. mine is the low version and had the standard bikes amount of oil in them.

I knew about that, presumably because of the difference between what's in (or not) each leg. Did you notice any difference after you put the correct amount in?
 
yes noticed a difference, not huge, but improved.
Just a small amount of oil make a big difference to the air gap.
 
Wow, good catch on the different oil heights. My SP was the same on both sides, so I guess the standard model has different guts.
 
Wow, good catch on the different oil heights. My SP was the same on both sides, so I guess the standard model has different guts.
The workshop manual says 230cc (do not specify which leg, so I'll assume its the same for both). It seems very low for me. What did you find out while doing the oil change?
 
The workshop manual says 230cc (do not specify which leg, so I'll assume its the same for both). It seems very low for me. What did you find out while doing the oil change?
Nothing really. It was a weird unconventional design that was both harsh and soft at the same time.
 
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That’s exactly the description. It’s like the high speed damping is too hard and no setting will remedy it.
 
You can use Spectro 7.5W as it's similar viscosity.

What you can do is lift the front end of the bike up so the wheel is off the ground and take both caps off. Measure the distance to the oil on the non-leaking leg, and duplicate that on the leaky leg. It might be tricky depending on how the fork is assembled, and might not work if it's a cartridge type.

The air gap is measured with the fork fully collapsed, no spring installed, so you can't do it that way without taking it all apart. Depending on your mileage, that might be a good thing to do anyway though.
2 forks is diffirent one dudes
 
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