Has anyone replaced the air filter housing with a pod filter?

[Lukas]

I rode a motorcycle and the spring is too hard for me I weigh 76 kilos I will try to change it for the original, if it works it will be great, but it may be that I will have to buy a shock absorber tomorrow I will take it apart and I would have to fill the shock absorber with nitrogen, because when it gets hot the air will expand and damage the seals.

[ChopperCharles]

This is why I'm going to a pod filter. I have bottomed the bike three or four times since I removed my raise-up kit, and when I inspected the airbox yesterday I found it was compromised.



One half of the case is split and no longer sealing. Plus the screw threads are showing.

Raising my bike fixed the contact problem, but left me with a far more dangerous problem. At or near 70mph actual, the bike starts to wobble and weave. I first noticed a little instability in the bike after I removed the stock hard luggage and all the associated bracketry. But raising the rear definitely exacerbated that. It makes sense, the rear is over an inch taller than it would be with the 15" rim the bike was designed for. An extra .75" on top of that was too much. With the stock parts back on the bike, I'm back to the pre-wobble state, where there's just slight instability at high speed in crosswinds. And I think switching to a larger front tire will fix that.

But in the meantime, I have no airbox. The intake manifold is an odd 43mm, but 1 3/4 is just over 44mm, so I ordered a 1.75" silicone tube, an adapter, and a 1.75" foam air filter. I'm going to tuck the air filter up under the left side cover, and build a partial airbox around it using a PVC tube that's at least an inch larger in diameter than the new foam filter. I want to keep the water out as much as possible when doing creek crossings. I'm also going to extend the plastic fender under the bike with a mud flap, and put a hugger on the swingarm, all to prevent dirt from being flung forward. This is because the airbox acted as an inner fender.

I looked at the amount of work to shorten the airbox front to back, and it would have taken way too much work and time, and a glued airbox is still not going to stay airtight forever, it's no longer structurally sound no matter how much epoxy you lather over it. Plastic welding might work, but the plastic welding kit costs more than the parts I bought to build a "cold air intake" using a name-brand UNI foam filter no less.

I now have significant room under the seat, which I may convert to tool storage. (So long as I leave the 8mm socket and ratchet somewhere else. I could also maybe put a PVC storage tube under there which would be accessible from the wheel well. I'll toy around with it a bit once I have the air filter assembled (waiting on parts)

Charles.

[ChopperCharles]

So.... I took the airbox out, hacked it up with a rotary tool, and then used a fiberglass repair kit (resin and woven fiberglass) to cover the open area near the battery. I didn't really have to close it up, but I figured the less dirt that can get into the filter area the better. I then coated it with flex-seal to make it black and to close up any voids that the fiberglass missed.




All this cutting allows the airbox itself to sit 1.5" closer to the front of the bike. I had to make an extension bracket for the rear mount and drill two holes and mount it with some 1/2" spacers.



Finally, you can see what I've done for my air filter here:



It's a 1 3/4" hose, 1 3/4" hose coupler, and a 1 3/4" foam UNI filter, with significantly more surface area than the stock filter. You can also see my crankcase breather peeking out from its new home. It has a 12mm hose coupler connecting the hose to the breather filter. All are oiled with Jeg's air filter oil, which came dyed blue.

My suspension is at the normal level and I have no wobble, no tire contact with anything under the bike, and I can run big tires on the back with no problems now. The only detriment to this is my maximum water crossing depth has been reduced significantly.

So, why did I hack up the airbox at all? Why not just remove it? Well... I looked into modifying a hugger rear fender to fit the RX3, and I looked at using a mudflap to create a new inner fender, but when it came down to it the stock airbox forms the rear fender and if I cut it apart I'd be able to protect my new filter from road dirt from several different sides. That's why I repurposed it.

If I start going on super deep water crossings again I'll have to extend the silicone line and basically build a snorkel.

Charles.

[Working_ZS]

I know the primary reason for doing this was to gain more swing room for the rear tire, but I'm curious as to how this setup sounds vs. the OEM intake. Louder or quieter? No change? The RX3 is a pretty quiet bike exhaust-wise; it's the induction noise that can get to you after a while.

[Lukas]

I'm waiting for an 11mm spring for a new shock I think in the original air box there is very little chance of water getting in and it can be silenced, but the original exhaust isn't quiet either, because it's a full-through muffler with 1 catalytic mesh I currently have 3 db killers and maybe I'll put a 4th on the muffler elbow and I don't understand what charlie means by saying the rear of the bike floats sideways, because in my opinion that's not normal behavior.

[ChopperCharles]

I purchased some sound deadening material from amazon, and added it to the left side cover, the left and bottom of the seat, inside on the top of what remains of my airbox, and I also used it to seal the original air intake holes.

It's a lot quieter now. The intake noise is still there, but now I hear the muffler more than the intake. It's way, way better when climbing steep hills. Before it'd be almost deafening even with earplugs in, and now it's pretty manageable.

I have no idea what Lukas means by "floats sideways".

When I run my front tire out I'll probably upgrade to the 19" front rim, and then revisit using a longer shock or shortened dogbones.

Charles.

[Lukas]

you wrote earlier

However, with the rear lifted this much the bike is VERY unstable at 70+mph. It has a dangerous wobble. I tried sliding the forks down in the trees as much as I could, but this only made it slightly better.

What do you mean by unstable?

[ChopperCharles]

This is what I mean. Start at 2:38.





This happens because there is not enough trail, and because I've reduced the weight of the bike significantly. The rear of the bike is lifted 1" over the design spec with a 17" tire. It's lifted even more because I'm using a knobby 80 profile tire instead of the stock 70 profile tire. Then it's lifted further because I have the shock preload set very high. Finally, I removed the side cases and racks, which resulted in the center of gravity of the bike to shift slightly, and also the rear to ride higher. Lifting the suspension even more with my dogbone modification was enough to cause the bike to develop a high speed weave right around 70mph. Going back to stock fixed it.

To make a bike more stable, you increase the trail. The easiest way to do this is by putting a larger wheel or tire on the front, to raise the front end. To make a bike turn quicker, you'd generally lower the front end by raising the fork tubes up in the trees. Lowering the front end or raising the rear gives the bike a "flickable" feeling, at the expense of high-speed stability. There is only so high you can go before the trail is too short and a high speed weave can develop.

Charles.

[Lukas]

Damn, you got me thinking charlie the spring will be here any day now and I'm afraid to get on a motorcycle those guys in those old videos are some hardcore.From this video it appears that this behavior is influenced by lifting the rear of the motorcycle , tire and the weight of the rider and trunk one motorcycle was all built up against the wind, yet it was tossing around

[ChopperCharles]

Note that my weave wasn't NEARLY as bad as those, but it was unnerving. I'm going to eventually get the larger front tire and then I won't have this problem. Unless I decide to sell it first. I'm a big fat guy and I need a little more grunt.

Charles.

[Lukas]

The 11mm spring from the Chinese guy turned out to have 10.5 and was way too soft to set the correct SAG, that is 3.5cm static SAG you have to tighten it a lot which measures the spring range the original white spring for me is too hard so I had to put on the original progressive, but that required rolling the locking pulleys now I just need to remake the shock head bearing from 10mm to 12 tomorrow I should be able to do that.
Recently I spent a few nights reading and I already know that I made a mistake, because I should make a spring for my weight and you charlie the same it is the basis everywhere I read it was mentioned I also read the actions of sqod raider and there someone wrote that he bought a progressive shock absorber from CSC and the spring was too small spring is the basis I found a motorcycle, I found a motorcycle with a shock absorber that I bought and it is a good shock absorber and it turned out that it costs 93$ in my country, this is important news, because these shock absorbers are commercial and rip people off the bike is called Diabolini Thunder 250 or MMR 250 only you have to ask what is the length of it in żongshen rx3 it says that it has 395, but measure shows me 390 strange.

[Lukas]

The minus is the change of the motorcycle geometry, but it is the fault of the Chinese for changing the wheel to a larger one without increasing the space in the wheel arch.
The problem with loss of stability in your case charlie is too soft spring this effect is called po go can be corrected by adding damping. Shocks with additional reservoir have in addition the option of adjusting the compression time in our shocks can be changed only by changing the oil density.