Backfire filter

Yogurt

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Dec 25, 1999
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#1
OK, I've been reading, and it seems the hot tip is to remove the backfire screen on the inner filter of four-strokes. I know this isn't any news, but I'm new to 4-stroking so bare with me. I'm assuming you just remove the screen from the inner cage, and not the whole inner cage? Am I correct? Also, I was looking at Twin Air's website... they have many things to offer. They have a Hi-Flow filter kit, that replaces the stock cage, and also provides a better sealing rubber strip around the filter base. And it also replaces the restrictive backfire filter. But they also recommend that you buy their Backfire Air filter. It has an added layer on the inside of their outer-filter. So my main question is, what are all you 4-stroke riders doing? Are you just punching the screen out from the backfire filter and running a normal air filter? Or have any of you bought one of these BackFire air filters once you replace the inner backfire filter? Seems like these Hi-Flow filter kits from TwinAir that are $105 may not be worth it. Thanks in advance, and pardon my ignorance.
 
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Dec 14, 2003
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#2
I have removed the backfire screen on my XR650R and run the stock filter support in a UNI filter. Knock on wood, I haven't had any problems with this set up. I have considered eliminating the stock filter support and buying a "high-flow" backfire screen because I have heard some horror stories of bikes catching on fire.
 
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#3
I just put a Twin Air filter system into my 2004 EXC 450 last week. The new cage is actually a pretty sweet looking piece. It clips the filter on nicely and actually makes it a bit easier to line the filter up with the airbox once you're ready to install it. You get a nice, tight fit and you can really tell that it's on there good.

When I bought the filter system, the guy at the shop said the filter element was so expensive because the inside had a special black filtering that was fire-proof. So there's no screen, but the filter supposedly will help prevent catastrophe if there is a severe backfire. It hasn't happened to me, so I can't guarantee that it works.

You're right, the price tag was a little hefty. It's supposed to flow 40% more air than the stock filter, but who knows if that's true. I'm one of those guys that puts K&N filters in his truck just on the off chance that it does some good. Hope that helps!
 

Rich Rohrich

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Jul 27, 1999
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#4
On the early YZF 400s there was no useful airflow difference with the screen removed when measured on a flow bench through the complete intake system .

The stock Yamaha airfilter flowed within a few cfm of the best air filter I tested (the TwinAir) . If I can get my hands on one of the new TwinAir setups I'll run the same tests on a CRF 450 .