Front suspension advise

[Magician16]

Originally Posted by Spins

Thanks for the video.

Fork oil upgrade was the first thing I did when I assembled the bike. I drained out what I could and replaced it with Maxima 15W. IIRC I was only able to remove 200ml from each fork. I assembled two Recons back to back and both drained the same amount . This did help firm things up a little compared to my older 18 Brozz.
I’m riding more aggressively now and I’m feeling the short comings.

When I worked on my forks yesterday, I had the exact opposite problem. When I drained the forks, there was about 260 ml. removed from the left side and over 300 ml. from the right side. Before the oil change, I had only about 2 1/2" of travel. I didn't ride it hard yesterday, but I was trying to test the travel so hit hard bumps at 20 mph. I got over double the travel and never bottomed out.



My Storm was used when I got it with about 3000 km on it, and I don't know if the previous owner had changed the oil. Whatever was in there looked like used motor oil and was dirty brown.

[Thumper]

Originally Posted by Magician16

When I worked on my forks yesterday, I had the exact opposite problem. When I drained the forks, there was about 260 ml. removed from the left side and over 300 ml. from the right side. Before the oil change, I had only about 2 1/2" of travel. I didn't ride it hard yesterday, but I was trying to test the travel so hit hard bumps at 20 mph. I got over double the travel and never bottomed out.

My Storm was used when I got it with about 3000 km on it, and I don't know if the previous owner had changed the oil. Whatever was in there looked like used motor oil and was dirty brown.

My Storm has a manufacture date of Oct 2020. I haven't looked into the fork oil yet, but the USD forks have full travel, bottoming out without too much of an impact. The lower end has a recessed ~6mm allen bolt just like the ones on the non-inverted forks I've worked on, but no drain port. I always used a mallet-style impact wrench to loosen that since the internals rotate freely when loose. I imagine this will be no different?

I just loosened the cap on the top end to open it up, but it keeps getting pulled inwards (!!) at end of thread travel, as if there is a vacuum inside the tube!

Does anyone have pics of this fork tube disassembly process?
Maybe the spring is holding it by friction (pushed into the cap), and you have to dislodge it??? But that doesn't make sense-too much force on the aluminum cap upon impacts, I'd guess. The spring can't be right up against that aluminum cap!

[Spins]

How long did you drain your forks! I didn’t allow them to sit over night. I assumed I did get everything out. Peace Sports specs list the capacity at 320ml. I’m might just try to add another 80 ml and see if this helps.

[Magician16]

Originally Posted by Spins

How long did you drain your forks! I didn’t allow them to sit over night. I assumed I did get everything out. Peace Sports specs list the capacity at 330ml. I’m might just try to add another 80 ml and see if this helps.

I actively pumped them about 20 times each. Every time I pumped them, I'd get some out. After a couple pumps I'd let them drain for a couple minutes. Probably less than an hour total drain time. I don't know how much you added, but Jasbeth's amount works well, less oil would equal more travel and/or bottoming out.

[Spins]

I removed 200ml and put back 200ml . I didn’t want to overfill them. I assumed I didn’t get everything out.

[Magician16]

Originally Posted by Spins

I removed 200ml and put back 200ml . I didn’t want to overfill them. I assumed I didn’t get everything out.

When I did my Magician, I put more oil in than I got out. I think it varies a lot, but if you didn't put at least 230 ml. in, you don't have enough for sure. Add 30 ml. to each side and check it out. If you still don't have enough travel, try another 20 or 30 ml.


I have never bottomed out either bike.

[Thumper]

I bottom out regularly on moderately deep holes like you might find in a road side drain going slowly. I don't think I have the right amount of oil in my fork.

I did find this excellent seal replacement video that shows the anatomy of a USD fork

[Megadan]

Originally Posted by Thumper

I bottom out regularly on moderately deep holes like you might find in a road side drain going slowly. I don't think I have the right amount of oil in my fork.

I did find this excellent seal replacement video that shows the anatomy of a USD fork

The way most of these cheap USD forks are constructed is very different from a big brand fork made by Showa or Kayaba that is often found on most big brand bikes. They are much simpler and more akin to a standard damping rod fork that just got inverted.

The issue you are complaining about sounds like the low speed damping is too soft, which is often also an issue with standard damping rod forks and it has to do with the way the damping is executed. Oil flows freely through the holes in the damping rod at low speed, so there is very little damping available, and at high speed it can become harsh because the volume of oil can't flow fast enough through those fixed orifices. This is why I installed fork valves on my Hawks forks, to reverse this functionality so that they operate properly for the conditions required. Higher end cartridge forks like the ones in that video have valves and shim stacks that regulate flow to function the same as the valves I installed in my Hawks forks. That is why those valves are often called cartridge emulators.

[Spins]

Originally Posted by Magician16

When I did my Magician, I put more oil in than I got out. I think it varies a lot, but if you didn't put at least 230 ml. in, you don't have enough for sure. Add 30 ml. to each side and check it out. If you still don't have enough travel, try another 20 or 30 ml.


I have never bottomed out either bike.

I think I’m going to add another 40 ml and retest.

[jasbeth]

Originally Posted by Spins

How long did you drain your forks! I didn’t allow them to sit over night. I assumed I did get everything out. Peace Sports specs list the capacity at 330ml. I’m might just try to add another 80 ml and see if this helps.

330ml is way too much, we ran numerous test on levels, travel and rebound on stock inverted shocks. We started at 330ml, and pulled out 5ml at a time until we found the best levels to keep for the action we wanted without bottoming out or feeling like there was no front suspension. 330ml and it will feel like you have no front shocks, stiff as hell. Again, the amounts listed work with all of the Chinese inverted shocks we have worked on. Riders weights ranged from 160-200lb's.