Using Belray Foam Filter Oil for Nitro RC

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bigfreak

Gone - bye bye.
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This is Belray Foam Filter Oil. It's used for offroad motorcycle air filter foams. If applied properly, it does a great job of protecting your engine. You also get about 1000ml for $8 as opposed to paying $12 for 100ml air filter oil marketed for RC Nitro. (You can pick up a quart at your local motorcycle shop. You probably have one just check your yellow pages.)

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As you can see from this pic, it’s a very sticky substance. It also doesn’t wash out with dish-washing detergent like other products. Brake cleaner is about the only thing I’ve found that will get rid of this sticky stuff. This sticky and stubborn nature makes it wonderful air filter oil, but on the flip side, it makes proper application a pain in the butt. This is because your foams can hold onto an obscene amount of oil. If you add too much oil, the excess won’t come out. You’ll end up suffocating your engine or leaning your needles to the point where you’re cheating yourself out of power.

The trick to using Belray air filter oil (for our purposes) is to work the oil in evenly and slowly from the outside. I do this by first putting a small amount in a clean, brand new plastic bag:

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(This is a lot of oil, but I oiled 6 foams.)

The next step is where I stray from tradition. Squish all of the oil in the bag up onto the sides of the bag. It’s so sticky that it will stay there. You don’t want a puddle of oil at the bottom. PUDDLE BAD!

Next, place the air filter foam in the bag. Be careful not to let the foam go to the bottom of the bag. You want to hold it up in the bag between the sides that are coated with the oil.

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Now it’s time to massage the oil from the sides of the bag into the foam. Just squish it and roll it and smash it and move it around the bag. The harder you squish the better. Most of the Belray oil will stay on the sides of the bag, but some of it will make a puddle in the bottom. Don’t let the foam touch that puddle! PUDDLE BAD!

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My crappy camera makes the filter look all splotchy and unevenly oiled. That’s not the case. What I took a picture of was a foam that is completely oiled all the way to the center. If your foam looks like the splotchy thing you see above, you need to massage it out. One way of knowing if you done is to look down the little hole in the center. It shouldn’t be white any longer, but light blue like the rest of the foam. It’s gonna take about 5 minutes of finger work per foam.

The next step is to install it into your air filter assembly. Never do this on the track. Ever. Also, wash your air filter assembly thoroughly with soap and water. Dirt is your enemy and you don’t want it anywhere near your new foam. It should be pretty self-explanatory though.

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If you think we’re done, you’re sorely mistaken. If you were to head out to the track like this, you probably wouldn’t be able to burn a tank of gas before the air filter was completely clogged with dirt. Your outer foam is your first line of defense and it shouldn’t be taken lightly. You need a high quality outer foam that is dense and able to catch 95% of the junk coming though. You should wash this foam with soap and water every couple of heats. I also spray it with WD40 after it’s been dried for a little added protection.

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(This is not a high quality outer foam. This is just the only one I have around right now. A good outer foam is much denser than this.)

Ok, so when should you change your inner foam? I use my thumb and I peal back the inner foam from the assembly to look at a cross-section of the foam. Depending on how good of a job your outer foam is doing, the finer bits of dust will work their way through the foam vertically. I change mine when I see the dust has worked about half way though the inner foam. (Again, don’t change it in dusty conditions.)

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This is a bad example because I only put a few heats on this foam with the above crappy outer foam. This does however show the technique.

I know I wrote a book, but I thought it was important that the less experienced folks see how seriously you should take air filtration. Nitro engines are expensive and proper care will extend their life expectancy. Also, sorry for the crappy pics. I didn’t know they were this bad until I saw them on the PC.
 
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That is nice, When I get a new air filter it is blue like that, makes you wonder if it is the same stuff, Cause my AFO is red.
 
Good info bigfreak. I have dirt bikes (check my gallery) so I am very familiar with belray and other filter oil. Speaking of expensive engines, dirt bikes go for 6-7,000 now! Anyway, you are right about washing the oil out, dish soap won't do it. I wash mine in a homemade solvent tank with kerosene (home depot). Then I squeeze it out and let it dry for a few hours on a piece of cardboard, because it pulls the solvent out of the fgoam. Then I wash it with hot water and liquid dish soap to get the kerosene and additional dirt out. Even after the kerosene cleaning, another 1/2 teaspoon of dirt comes out of a cycle filter with the soapy water.

To re-oil, I also put it in a plastic bag. I let it get completely soaked in oil. It is bad to leave too much oil on it, so I squeeze the oil out real hard. Then wrap it with a paper towel or rag and sqeeze again.

I do my nitro filters the same way. Leaving the filter lightly oiled does help air flow, but reduces the amount of dirt it can trap, so you must clean it more often.
 
I was using the pre-oiled OS filters. I switched to mugen foams with Belray oil. My first time out, I obviously had too much oil. I had squeezed the crap out of it too. When I ran with the new oil (too much), my engine ran freakin rich as a mofo. I had to lean out my needles just to finish the race day. Less air, less fuel, less power. That's when I started doing it as I described above.
 
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