CFM airbox

Blastinit

Member
Apr 14, 2013
99
15
50
SW Washington
I have been considering buying the CFM airbox. What are the pros/cons of this unit? Also, what am I going to have to do with my jetting? I currently have a 290 main, Blue needle in the middle, FMF Fatty/Turbine core 2, Boysen reeds, +4 timing mod, Bone stock engine/carb. Thanks.........
 
the cfm will need treated the same as an open airbox and aftermarket filter, requiring 2-3 sizes larger main jet and airscrew adjustment.
if your already jetted for an open airbox and A/M filter you may be ok ?
only a plug chop will tell.......
http://www.blasterforum.com/carburetor-138/how-plug-chop-53237/

you do know you need to cut the stock airbox from the rear fenders ?
and i highly suggest a different box to carb boot than the one cfm supplies, the cfm tube is 2.5", you'll need to measure the back of your carb to determine what size reducer you need from here.........
Intake Pipe Reducer

i use a 2.5" x 2.25" for my 34mm carb
 
Thanks Guys! I currently am jetted for an open airbox lid w/ K&N filter - Outerwears. I am aware of having to cut the original out of the fenders, yet another reason I want this. The factory airbox/battery box (LOL), etc. is an eyesore. I like the trick look of the CFM!
 
I have a CFM on mine and I really like it. Much better air flow then stock. The Ir box to carb tube has much better flow then the funky stock one.
 
I also run a CFM box. Huge improvement over stock, and it is very easy to install once you get the stock box cut out. The only problem with them is the funky mounting 'pin' which is supposed to lodge against the frame and hold the airbox in place. It doesn't fit properly, at least not on my Blaster. It needs some modding to work correctly. I wrapped mine in layers of electical tape to increase the diameter and allow it to 'lock in' better.

If you've never tried one, the by far and easiest way to cut your stock airbox out is with an air body saw. You can get one from Harbor Freight, and these little handheld pneumatic sawzalls will zip through anything thin, with no melting of the edges and none of the bulk of an electric saw.
 
Something to look out for - The screw holding my CFM box to the left side of the frame "ripped" a hole higher up than the stock hole. I'm guessing the reason for this is from improper fitment on the opposite side of the box where the round metal piece is supposed to "jam" in the corner of the frame and / or the amount of ridiculously rocky terrain i ride in bouncing the hell out of it and creating excessive wear. I'm going to have to weld a piece of aluminum on there and modify the other side of the box to protect against any further wear.

7OAOWZq.jpg
 
The cfm boxes are great.I cannot comment on the mounting issues as I tossed there mounting instructions out and made my own mounts.If you buy one let me know and I will take some pics fopr you to get some ideas.Also if you buy one then go to your local auto zone,etc and order a k&n filter through them.There like $30-35 there and $55 through cfm.Also an outerwears filter skin is a great investment to riun with the air filter.
 
bought my cfm used, it came with no mounts, so i made mounts too, angle aluminum bolted to the box then under all 4 of the back fenders bolts.......

4789-cfm-box-mounts.jpg


i hear the cfm to carb boot isn't the best either, but these are, you'll need 2.5" for the box side, then measure the back of your carb for the reduction size, my 34mm takes a 2.25"...........

Intake Pipe Reducer
 
^^^^^^^^^^Exactly how I mounted mine.Toss the cfm hardware in a box and make your own. A silicone intakes reducer is a must also.
 
I bought one of those silicone intake reducers and it was really hard to use because of angle differences between the carb and the box. I guess if I remounted the box for the angle of the carb it would work well but I'm lazy so I put the reducer on the shelf and I just make sure there's no leaks with the CFM boot every time it goes on or off.
 
/\ yes you must mount the box to align with the carb.
the silicon boots are way more flexible than the fernco plumbing fitting supplied by cfm, so not sure how it worked better for a misaligned box the the silicon ??
 
I run 3 of the silicone intake reducers with all 3 of my cfm boxes.All line up very well and make it alot easier to use than the cfm's cheap ass home depot plumbing fernco fitting.I have a feeling nofx that you may have a different style carb intake that comes off at a different angle.I have seen this.I bought an intake boot once and it was a straight outlet and not at the 30 degree angle as it should have been.I personally would not run anything besides a silicone intakes reducer.More meat on the bone to seal and alot more user friendly.Also the silicone intakes clamps are very nice.For the extra $4 or $5 it is well worth it to buy the clamps also.
 
bought my cfm used, it came with no mounts, so i made mounts too, angle aluminum bolted to the box then under all 4 of the back fenders bolts.......

4789-cfm-box-mounts.jpg


i hear the cfm to carb boot isn't the best either, but these are, you'll need 2.5" for the box side, then measure the back of your carb for the reduction size, my 34mm takes a 2.25"...........

Intake Pipe Reducer

how is that spectre filter workin for ya?
 
how is that spectre filter workin for ya?

that spectre filter is working great..........
on my buddies dodge neon I:I
it came with the box when i bought it used for $50, that filter was taken out as soon as i got the box mounted. it was never even started with that POS.

surely you don't think i'd ri$k the KOR motor i have to anything but a well oiled uni filter do ya ?? :D
 
that spectre filter is working great..........
on my buddies dodge neon I:I
it came with the box when i bought it used for $50, that filter was taken out as soon as i got the box mounted. it was never even started with that POS.

surely you don't think i'd ri$k the KOR motor i have to anything but a well oiled uni filter do ya ?? :D

Uni filters are the only way to go!