BMC Race Filter

[btreaves]

Hey Fellas,

I just purchased a brand new BMC from a friend for my 2000 Hayabusa, but unfortunately it didn't come with any instructions.

The filter comes with this foam pad that I assuming I'm suppose to either stick onto the bottom of the filter or stick on the bottom of the air box. I'm not sure which. If it's suppose to be stuck to the bottom of the filter why didn't they just do that from the factory?

Anyway, can anyone tell me which way is correct.

Thanks in advance!

 

[CorrodedAlien]

...where'd ya get it and how much? I'm looking to get one 4 my '03. Looking 4 under $80...

 

[SierraFlyer]

If you got the race version, it will not fit in a stock airbox without mods to the box. The street version will fit however.

Yes the foam goes on the bottom of the filter to seal it against the bottom of the airbox. If you look at the bottom of the airbox, there is a 1/4 " tall ridge on the bottom in the shape of the airfilter inside edge. It is used to guide the filter straight down. The "race" filter has a smaller inside diameter and it won't fit over the ridge, The ridge has to be removed for the filter to seat down completely. The easiest way is to just sand off the ridge with a dremmel or die grinder.

I went a little further with a small box mod. I cut the bottom of my airbox out using a dremmel and guided it by cutting around the outside of the ridge. This removes the flapper, its housing and the surrounding plastic to the inside edge of the filter at the foam seal. Then you can remove the vaccuum motor that controls the flap and the vaccuum hose too this way. Then plug the remaining hole in the airbox bottom with something useful - like a dry Nitros nozzle

 

[btreaves]

Thanks for he info...How do I know if I got the race filter or the regular filter...I can't tell by looking at them I guess. I really don't want to do any modifications to my air box.

 

[SierraFlyer]

The two look almost identicle. The difference is that the bottom edge of the filter is wider on the race due to the deeper pleats. I mean if you take the stock filter and the BMC and turn them up-side down so the opening to the inside of the filter is facing you, you will see a "D" shaped opening. The outside circumfrence of the filter is the same, but the race filter has a smaller inside opening. The ring is wider because the pleats are deeper. If they are the same size on the inside (the "D" shaped ring is the same width) then you have a non-race version.

 

[SierraFlyer]

The two look almost identicle. The difference is that the bottom edge of the filter is wider on the race due to the deeper pleats. I mean if you take the stock filter and the BMC and turn them up-side down so the opening to the inside of the filter is facing you, you will see a "D" shaped opening. The outside circumfrence of the filter is the same, but the race filter has a smaller inside opening. The ring is wider because the pleats are deeper. If they are the same size on the inside (the "D" shaped ring is the same width) then you have a non-race version.

 

[SierraFlyer]

The two look almost identicle. The difference is that the bottom edge of the filter is wider on the race due to the deeper pleats. I mean if you take the stock filter and the BMC and turn them up-side down so the opening to the inside of the filter is facing you, you will see a "D" shaped opening. The outside circumfrence of the filter is the same, but the race filter has a smaller inside opening. The ring is wider because the pleats are deeper. If they are the same size on the inside (the "D" shaped ring is the same width) then you have a non-race version.

 

[SierraFlyer]

The two look almost identicle. The difference is that the bottom edge of the filter is wider on the race due to the deeper pleats. I mean if you take the stock filter and the BMC and turn them up-side down so the opening to the inside of the filter is facing you, you will see a "D" shaped opening. The outside circumfrence of the filter is the same, but the race filter has a smaller inside opening. The ring is wider because the pleats are deeper. If they are the same size on the inside (the "D" shaped ring is the same width) then you have a non-race version.

 

[The Oracle]

If you got the race version, it will not fit in a stock airbox without mods to the box. The street version will fit however.

Yes the foam goes on the bottom of the filter to seal it against the bottom of the airbox. If you look at the bottom of the airbox, there is a 1/4 " tall ridge on the bottom in the shape of the airfilter inside edge. It is used to guide the filter straight down. The "race" filter has a smaller inside diameter and it won't fit over the ridge, The ridge has to be removed for the filter to seat down completely. The easiest way is to just sand off the ridge with a dremmel or die grinder.

I went a little further with a small box mod. I cut the bottom of my airbox out using a dremmel and guided it by cutting around the outside of the ridge. This removes the flapper, its housing and the surrounding plastic to the inside edge of the filter at the foam seal. Then you can remove the vaccuum motor that controls the flap and the vaccuum hose too this way. Then plug the remaining hole in the airbox bottom with something useful - like a dry Nitros nozzle  

I have an '03 and bought a racing BMC. It fit perfectly. Later, I did the medium airbox mod anyway. But, it wasn't necessary for fit in mine.

-Rip.

 

[btreaves]

So basically I should just take the stock filter out and see if the BMC filter I have will fit and screw down. If it doesn't I've got the race version...If it does...I've got the regular version. I'd prefer the regular version at this point, I don't wanna cut my air box.

What I may do is cap off that vacuum hose so that the flapper valve always stays wide open (the poor mans airbox mod). I'm gonna see how it looks on the dyno. It may be easier to launch the bike at the drag strip with that setup. Just a thought.

Thanks again for any help you can provide.

 

[Henryace1]

The way you can tell is. On the STREET version is 204/11 on the RACE version 204/11 race which should be on the side of the box that the filter came in.

 

[SierraFlyer]

We need to be very careful because the race will ALMOST seat in the airbox when sitting on top of the ridge. It sits up almost 1/4" (.190" to .210"). The filter top won't fully seat down and seal the "O" ring on the filter top. Then when you tighten the screws it pulls the airbox top up to meet the airfilter top, distorting both and not sealing correctly. This will allow dirty air to leak onto the clean side of the filter and into your engine.

 

[SierraFlyer]

We need to be very careful because the race will ALMOST seat in the airbox when sitting on top of the ridge. It sits up almost 1/4" (.190" to .210"). The filter top won't fully seat down and seal the "O" ring on the filter top. Then when you tighten the screws it pulls the airbox top up to meet the airfilter top, distorting both and not sealing correctly. This will allow dirty air to leak onto the clean side of the filter and into your engine.