Honda TRX450R - Breather Configurations

Breather Mod One

I had been seeing a lot of people on several different forums relocating their crankcase and valve cover breathers, so I thought I would do my own. It was a pretty quick job, I just re-routed the existing hose to the rear of the opposite side of the air box, and installed a small filter. For this mod, I kept the valve cover and crankcase breathers together on one hose/line. I decided to do it this way since it was only one 90 degree bend, and only about 7 inches of hose extended onto the current line. This way, it kept the crankcase breather out of the way of the air filter, yet still inside the air box where it will stay clean. Quick, simple, easy, and cheap...only cost $13 total for the materials.

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Breather Mod Two

This time I decided to go with two separate breathers. One line coming directly off the valve cover and back to the airbox. And one line coming directly out of the crankcase and back to the airbox. So, no more breather "T." It was a pretty quick and easy install on a rainy day. I had hoped this setup would make the bike rev a little quicker, not sure if it actually did.

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Breather Mod Three

This mod isn't much different from breather mod two. Same hoses, same filters, just different locations. The need for the filter relocation came with the installation of the Fuel Customs Intake and the larger filter that must be used in conjunction with the intake. The new air filter ended up being too long for the breather filters to be located in the rear of the air box like they were for breather mod two. I cut the lines and moved them closer to the engine (see pics below). The advantage of this setup is that the hoses are much shorter. The disadvantage is that the filters are no longer contained within the air box and they'll get dirty much faster.


Breather Mod Four

For this iteration I decided to buy all new line, fittings, hoses, and filters to re-plumb the entire breather setup. This was going to be done exactly like the previous breather modification except using all new materials and straight fittings rather than 90* fittings for attaching the filters to the hoses. Since this setup was almost exactly like the last, the installation went very quickly.

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Breather Mod Five

This mod isn't all that much different from the previous few breather modifications. Same style hoses, filters, fittings, and clamps (all brand new). The location of the filters has changed slightly as I've switched from the Fuel Customs Intake back to the OEM intake boot using the DASA intake ring and billet intake resonator plug. With the FCI, there was a lot more room for the breather lines and filters; not so much with the OEM intake. I decided to put the crank case breather filter directly on the top of the crank case...no hose needed and it fits very well. The valve cover breather line was extended a bit to clear the OEM intake boot and wiring harness. This is a very "clean" looking setup, but the filters may get dirty very quickly and will probably need to be cleaned and/or changed often.


Breather Mod Six

Again, this mod is a slight evolution from breather modification five - It just shows the use of a billet resonator plug in place of the stock plastic resonator. This makes the setup less bulky - but, it's been shown on the dyno that having the resonator hole plugged may cause a loss of a couple HP in the lower part of the RPM range. This new setup also shows the Racer's Edge AZ large paper style filter; but, it still uses the same style hoses, filters, fittings, and clamps (all, once again, brand new). This is probably the cleanest looking setup to date; but the filters may get dirty very quickly and I will probably be putting the stock resonator piece back on the intake.

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