Fork oil change

[GooseMan]

I've been riding my Atomik mid size around for a while now and have found that the front forks just don't feel right. When riding over small annoying bumps it feels like there is no suspension at all but when I hit a big pot hole and it bottoms out completely. I don't want to spend too much (like getting new forks), I was thinking of changing the oil but don't know which oil to buy. I only weigh 75kgs, unless somebody else has a beter solution?

All help much appreciated.

 

[dynamicgs]

my atomik forks crapped themselves too... they are really bad forks man... get yourself some decent forks and it will feel like a new bike!
I tried the oil thing and it didnt help... the plastic spacers inbetween the fork springs in mine had busted up and gone all through the fork oil... which stuffed up the movement of oil through the fork leg...

 

[Carlts]

Hey man,

Before going all out and changing forks, try changing the oil you will be amazed at the improvement.

Pre Oil change
My brothers Atomik was painful to ride, every bump vibrated you down to the very bones lol. We decided to drain the stock oil and lo and behold we were utterly amazed as the rubbish that came out. It was literally like black water, it smelt burnt and festy and had no likeness to oil, phew what a scare. But heres what we did:

1. Took forks off bike (easiest way is to remove front wheel and slide each fork out of the clamps)
2. Took the top caps of both fork legs (might have to unscrew bleed valve first)
3. Drained both fork legs completely, found each had 150ml of rubbish liquid. Will have to pump the legs to get it all out
4. Refilled each fork leg with 150ml of 15w oil (just ended up using my engine oil as it was the right weight) Atomik forks are quite soft from factory so heavier weight oil is recommended, especially for those on the medium to heavy spectrum.
5. Replace caps, refit forks and ride​

Verdict
After doing the change, the bike was like new, wow it was amazing, we hit the 1 hour enduro track at QLD Moto Park and they never missed a beat. Each bump was absorbed with ease, even made the MX jumps a breeze.

Don't be daunted, it is an easy task and well well worth it!!!!!

Try it man,
Carlton

 

[cloud_2901]

Hey man,

Before going all out and changing forks, try changing the oil you will be amazed at the improvement.

Pre Oil change
My brothers Atomik was painful to ride, every bump vibrated you down to the very bones lol. We decided to drain the stock oil and lo and behold we were utterly amazed as the rubbish that came out. It was literally like black water, it smelt burnt and festy and had no likeness to oil, phew what a scare. But heres what we did:

1. Took forks off bike (easiest way is to remove front wheel and slide each fork out of the clamps)
2. Took the top caps of both fork legs (might have to unscrew bleed valve first)
3. Drained both fork legs completely, found each had 150ml of rubbish liquid. Will have to pump the legs to get it all out
4. Refilled each fork leg with 150ml of 15w oil (just ended up using my engine oil as it was the right weight) Atomik forks are quite soft from factory so heavier weight oil is recommended, especially for those on the medium to heavy spectrum.
5. Replace caps, refit forks and ride​

Verdict
After doing the change, the bike was like new, wow it was amazing, we hit the 1 hour enduro track at QLD Moto Park and they never missed a beat. Each bump was absorbed with ease, even made the MX jumps a breeze.

Don't be daunted, it is an easy task and well well worth it!!!!!

Try it man,
Carlton

15 weight engine oil is about equivalent to 0W fork oil.

Different viscosity ratings for the oil.

Don't use engine oil in your forks, get some Motorex Racing Fork Oil 7.5W, as its actual viscosity rating is about 35 cSt at 40degrees celsius, about the weight you are after in a pit bike. The oil you are using, is far too thin, and you would be using far too much, and compromising the oil / air ratio inside the forks, thus promoting hydro-lock of the forks faster.

My atomik 140's forks took about 120ml of Motorex 5W, but I would go with the 7.5W next time.

If anyone is interested in other oil's comparative weights (as every oil manufacturer uses a slightly different method of determining their oil weight, same system, but different way of measuring), there is this table here:

Peter Verdone Designs - Low Speed Damping

This guy, who knows what he's talking about, rates Silkolene / Redline oils as the best, due to their higher Viscosity Index, which increases their ability to perform under rapid temperature changes, which is what happens inside your fork.

So by his table, the Silkolene Pro RSF 7.5W is the one to go for, up over 300 on the Viscosity Index, and the right viscosity grade (i.e. weight) to work right.

For more info on why you don't want to to use too much oil and change the oil/air height at all, Peter Verdone Designs - Oil Height

 

[GooseMan]

Cheers guys, this has helped alot, will go get some of what cloud siad above^.

 

[Carlts]

Good info there clouds, forks are performing and holding up well however. I would take more care on a a better bike though....

 

[GooseMan]

Hey clouds what was wrong with the 5w, cause I don't do alot of jumps, mainly bush bashing and hill climbing?

 

[cloud_2901]

Hey clouds what was wrong with the 5w, cause I don't do alot of jumps, mainly bush bashing and hill climbing?

Well, nothing WRONG with it, I just felt with my bike 7.5W would hold the forks a bit higher in the stroke, get just a touch too much sag with the 5W, and seeing as there's no other way to adjust it, heavier oil is the go, screwing with the oil to air ratio by taking out oil will not help the performance of the fork (well, it might a bit, but it might make it far worse very easily, you need to really know what you're doing)

Much easier to play with the oil weights and leave the height alone.

And as the comparative brand table in that link I posted earlier shows, you have a LOT more range with oil than you'd think from reading the bottles, just by changing the brand of oil.

 

[GooseMan]

All finished now and is great thanks

 

[krazed0451]

I think we need to clarify something here...
Carlts/Cloud - Mid size or regular? It's entirely possible that a regular sized Atomik's forks only take 120ml and the mid size takes 150ml. Just measure what comes out and replace with the same.

Don't forget to spread a little reputation around guys

 

[GooseMan]

My midsize took 200ml but a little less would still work

 

[user 9190]

Just cleaned out my forks on the atomik motox 125cc for the first time. Found about 200ml of smelly black liquid of some sort in each. Replaced with some 10w (same qty) and to be honest cant feel much difference. Standing over it i'm still able to almost bottom them out although the action does feel a little smoother.

Reckon adding a heavier weight fluid will help or do I just have dud forks?

 

[user 9190]

Also does anyone if the stock rear shock can be refilled? I noticed it has just about nothing in the way of damping any more.

 

[timeeh]

You could try more oil (I ran about 250ml on my STD Nitrous) As for the rear shock, not too sure but i don't think so.

 

[Carlts]

Old thread I know but just to clarify that was 150ml for the Atomik Reign Midsize bike (however its an old bike so could've easily been 50ml off).

My DNM mid size (730mm) forks took exactly 200ml as pictured:

 

[dynamicgs]

Hey Carlts... Did your DNM's feel any different/better after changing the factory oil?

 

[Carlts]

^^^ A world of difference man, especially because Im only 60kg, they were way to stiff from factory.

 

[cloud_2901]

The oil that comes in those Chinese forks is just cooking oil, I swear. When I took mine out I could smell what smells like burned vegetable oil when you leave a pot of it on the stove until it's all gone.

Makes such a huge difference, even if you don't change the level at all, just put some proper fork oil in.

 

[Carlts]

^^^ lol yer the smell is horrid. Especially coming from a second hand bike that has who knows how many hours on the stock oil

 

[jpbullough]

Hi guys found some very good info here, thank you.
Can anyone advise me on oil quanties for a set of fastace forks off a 2006 orion 125, they have the rebound & dampening clickers on top 710mm axle eye to of fork 48mm OD chamber.
Am strugling to find info on them so any help is greatly appreciated.