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Discussion Starter · #1 ·
Guys,
Last week I ordered a bunch of fitting, and fork oils to design a set of air valves for the Grom front forks, and improve the fluids response to the forks movement. First I blended a couple of fork fluids together to make a slightly heavier fork fluid, to improve the dampening. Next I designed and machined 2 air valve assemblies for the re-machined top fork nuts. I removed my machined spacers from the forks, when I installed the air valves, so the forks are at stock length. I added my new fork oil, and tried various air pressure, 18 psi being the best for my weight. What a difference in the way the bike responds & feels in a corner. It's like night & day. I am not an advocate of tearing the complete forks apart to replace the springs, since sliding tubes were not designed to be disassembled by Showa. It's way easier to just remove the forks, drain the oil, and add parts to the top end that fix the problem. I ordered a second set of Honda fork top nuts to time myself, so that I can see how much it will cost to convert the system to air assist. Please look over the pictures,
Brian



 

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Can you just put a schrader valve in there instead of the T with shrader?

This reminds me of dirt bike forks. I like the idea just not the sight of the thing. So you can take out the cap nut willy nilly? On standard size inverted forks its attached to the cartridge and it has to be removed from the cartridge to get it off. It the top retainer for the spring. How are the grom forks constructed. Everyone talks about how difficult they are. Are the not just little versions of standard sized forks? Id like to see a exploded view of the construction.
 

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Discussion Starter · #11 ·
How the Grom forks work

Guys,
On almost any set of normal forks, all I had to do was take off one fork top cap at a time, drill & tap it in the lathe in one of my metric thread machined holding fixtures, screw in a schrader valve, and I'm done: Air Forks. The Grom/MSX125 forks, being upside down style, that are just a little unusual, take a little more work. The 8mm bolt in the center of the top screw in cap is there to hold the center dampening rod which push's down the spring. So, you can't eliminate the bolt and add a schrader. The bolt, which maybe longer, still has to be there. The "T" is forged brass, so it's really strong. Could you make a billet aluminum "T", say, anodized black, sure, is it worth it, I don't know, not to me. I like the look, and I love the change. There is also a whole lot of machining inside the cap, see the photo. Nothing is easy on this bike! The fork oil was as important as the extra spring tension.
Brian
 

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awesome!
 

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Discussion Starter · #14 ·
Does the air stay in the forks?

That is actually a great question.
Well, I'm on day three without a change in air pressure. I have a low reading pressure gage, and a 0 to 40 psi regulator with a flex hose & schrader valve coupling. There is so little air in the forks, by volume, that it's hard to say 100% that it has not changed. If I want 18 psi in the forks, then I set the regulator at about 22, because some air bleeds out when you pull off the schrader valve. When I installed the kit, I used special sealing washers from McMaster-Carr Supply, they are really one of the tricks to making this air fork idea work. The forks tonight feel the same as they did on Saturday. If I want to recharge them, it takes me about a minute or so, so it's no big deal. That's the reason I positioned them facing to the front, it makes it super easy. I road around Sunday for about 8 miles, and they did not change, and the bike handled way better. Now I want to install my new YSS adjustable shock, and aluminum swingarm.
Brian
 

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good answer..

You answered it perfectly, you knew exactly what I was trying to wrap my head around.
Thanks


Guys,
On almost any set of normal forks, all I had to do was take off one fork top cap at a time, drill & tap it in the lathe in one of my metric thread machined holding fixtures, screw in a schrader valve, and I'm done: Air Forks. The Grom/MSX125 forks, being upside down style, that are just a little unusual, take a little more work. The 8mm bolt in the center of the top screw in cap is there to hold the center dampening rod which push's down the spring. So, you can't eliminate the bolt and add a schrader. The bolt, which maybe longer, still has to be there. The "T" is forged brass, so it's really strong. Could you make a billet aluminum "T", say, anodized black, sure, is it worth it, I don't know, not to me. I like the look, and I love the change. There is also a whole lot of machining inside the cap, see the photo. Nothing is easy on this bike! The fork oil was as important as the extra spring tension.
Brian
 
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