4 Stroke Air Box Screen

So I have read a couple articles about removing the screen that is either part of the air filter cage or attached to the air box on 4 strokes. I read that all the factory guys do not have them in their bikes and have read that it does or does not do anything for performance change.

Also read that they are in there because 4 strokes have a tendency to back fire and it could catch the air filter on fire. Bike companies have the screens in the bikes to Cover Their Asses from what I understand.

So the questions is, have any of you 4 strokers removed the screen on your bikes? If so, did you honestly feel a performance difference? I have not done this to mine, but sometimes I wake up :thinking: about stuff and wonder.

So let's hear it DBAers, or am I the only one that is thinking about this?
 

SRAD97750

Moderator
Staff member
Technically it would be considered an airflow deviation. So removing it would surely (though minutely) add AIR to your air fuel mixture.
Would you need to rejet or 'feel' a performance gain? I doubt it would make that kind of difference.

There is a possibility that it could cause an intake fire if it backfired, but not likely. -BIG DAN:thumb:
 
Technically it would be considered an airflow deviation. So removing it would surely (though minutely) add AIR to your air fuel mixture.
Would you need to rejet or 'feel' a performance gain? I doubt it would make that kind of difference.

There is a possibility that it could cause an intake fire if it backfired, but not likely. -BIG DAN:thumb:
That is kind of what I was thinking. I also read that if you do this and want to make sure you do not get a fire, to use non-flammable oils on the filter.
 
I removed mine but immediately regreted it after my first ride. I noticed that my bike popped a lot after I removed it. I didnt feel a big difference in power gain or loss, but I did notice little black marks on my stock air filter. I run a little rich when I ride at high altitude where I noticed it the most. So I ordered a new screen and a uni air filter which is flame resistant. After that the bike runs like a champ and no more popping. :thumb:
 
I have not removed mine because I don't think I would ever notice the difference and I like having it there to catch anything that might get that far up in the event of a misfire.
 
I remember back in the 90's that Scott Summers did not remove the screen from his race XR600. He said it caused a slight loss of snap at the very bottom end. He didn't feel that the gain on the top was worth it. I was never able to test this theory as my 600 was missing the screen when I bought it.

My 600 was not very backfire prone, but it did happen on occasion. Never had the filter catch fire.

One thing is for sure, removing that screen will change the intake characteristics. It may well require some carb changes to adapt to the new setup. The screen on my Beta seems rather restrictive. I would plan on some jetting changes if it were removed.
 
So I have read a couple articles about removing the screen that is either part of the air filter cage or attached to the air box on 4 strokes. I read that all the factory guys do not have them in their bikes and have read that it does or does not do anything for performance change.

Also read that they are in there because 4 strokes have a tendency to back fire and it could catch the air filter on fire. Bike companies have the screens in the bikes to Cover Their Asses from what I understand.

So the questions is, have any of you 4 strokers removed the screen on your bikes? If so, did you honestly feel a performance difference? I have not done this to mine, but sometimes I wake up :thinking: about stuff and wonder.

So let's hear it DBAers, or am I the only one that is thinking about this?



Don't do it......

Its engineered into the overall performance of the stock motor.... unless you throw 5k into the motor and need that miniscule amount of air flow blockage to dissappear... you'll get more from a polished carb.
 
Don't do it......

Its engineered into the overall performance of the stock motor.... unless you throw 5k into the motor and need that miniscule amount of air flow blockage to dissappear... you'll get more from a polished carb.
I figured I have got along for 6 years without removing it, but was just curious if others have and if they noticed any diff.
 
I figured I have got along for 6 years without removing it, but was just curious if others have and if they noticed any diff.

Well if you decide to do it remove the silencer packing and add some Sikk graphics as the power increase will be to the 3rd power then.....
On a side note* do you add a little premix to your 4T fuel? I got a source that says add some... I add about a qt of premixed fuel in with Lukes tank on the RMZ. The reason being that it extends the life of the valves by keeping them cooler and more lubricated. The bike does start easier when its hot
 
I did it on a XR100 cuz it was sooo restricted by the screen in those things. I have also actually seen a fire in the air filter and seen a few filters after the fires. I did not remove mine on my KTMs cuz they are only one layer thick and it seems the safety factor is worth a little bit of gain lost,
 
I did it on a XR100 cuz it was sooo restricted by the screen in those things. I have also actually seen a fire in the air filter and seen a few filters after the fires. I did not remove mine on my KTMs cuz they are only one layer thick and it seems the safety factor is worth a little bit of gain lost,

To do it or not to do it aside, if you do do it you just replace the stocker with one that has the "fire-resistant" material inside. Most of the big after market manufactures make them....Twin Air, No-Toil...

Again, personal choice but if you do decide to do it you can do it without fear of burning most of the hair off of your ass. It is easier to explain than a brazilian wax and much less of a hassle:

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