A good and inexpensive Air Box & Filter for JM 250's

Materials:
Fram Air Filter "CA3373" (you cut it into 3 pieces and get 2 usable filters) $6.00 at Walmart.
Lock & Lock Brand, 5.1 Cups Multiple-Use Storage Container - UPC "034641 082385" at Walmat, about $3.00.
Clear Silicone RTV Sealer.
A ½" black rubber grommet from the hardware store.
The black rubber connecter tube and clamp from the present air filter.

Air Box Construction:
Cut an approximate 1-5/8" diameter hole on the bottom side of the base, centered approximately 1-5/8" in from the right edge of the foot ring on the bottom and up about 1-1/4" from the same foot ring. The hole should be at approximately 4:30 looking at the base upside down.

Drill another ½" hole about ¾" down from the top foot ring and in ¾" from the left side foot ring. It should be at approximately the 11:00 position. This is for the crankcase breather tube.

Cut an approximately square hole in the lid. Leave about 1/8" on the two sides and about 3/8" top and bottom from where the flat center section of the lid turns into an upward curved roll.

Cut Air Filter:
Line up one end of the Fram Air Filter against the square hole in the Air Box lid. Cut filter accordingly, making sure that you cut the paper filter material along what will be the outside of the finished assemble - so that you can tape / silicone the cut edge to the storage container lid.

Install Rubber Tube Connector:
Take the black rubber tube connector from the old filter and force into the 1-5/8" hole that you cut in the bottom of the storage container. Work the mounting groove all the way in. Also force the ½" rubber grommet into the small hole.

Silicone Seal Everything:
Run a small bead of silicone all around the outer edge of the filter. You might have to tape the loose "Cut" paper edge of the filter. Run a bead of silicone around the outside of the black rubber mounting tube.

Install the Airbox Filter Assembly:
Put the Lid / Filter Assembly on the base and install in quad. The whole assembly is a tight "friction fit" and really doesn't need any screws for mounting. While mounting the black rubber tube on the carburetor, force the tube down past the carb - then back up, so that the bottom edge is on the flange and you can see the top edge to work on the carb with a small screw driver. Cut and force the crankcase breather tube into the ½" grommet.

To Change Air Filter:
Remove air box assembly from quad. Remove air box lid. Remove old filter from lid. Remove remnants of old silicone from lid. Cut new filter from other end of Fram Air Cleaner Filter and silicone in place. Reinstall assembly back into quad.







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While in the USAF I worked on Jet Engines for C-130's (In left Pic a C130 is Air Unloading an Army Tank) and B-52's (In Right Pic of B52 that's a School Bus in Lower Right)

Good work, very interesting airbox idea!

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I was worried about you using a paper filter until I saw how its mounted. Looks very protected from water. Very cool idea NJDale.

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07 Jetmoto 250 Sport
07 90cc Mini Ute
06 Jetmoto 200 Enduro
06 Jetmoto 200
06 Jetmoto 150
06 Jetmoto 125
04 Yamoto 150
01 KTM 400 EXC
92 WR 250
91 CR 250
88 YZ 80
85 CR 500
83 XL 600
82 XR 200
79 XR 75
79 Odyssey
73 Bultaco 360
71 Rickman Montessa 250
70 Rupp Enduro
69 Honda 50

i just used a tupperwear contaner, i like ur idea better

I've been re-considering the design - maybe a phase II; If I can find the right size container and maybe put a 1-5/8" or 1-3/4" rubber elbow out of the carb and turn it "up" and into the "bottom" of the box - and put the filter flat ways on the "top" of the container. This would raise the "swamp-out" heigth by 3" to 4", or about just even with the bottom of the seat or slightly higher than the exhaust. Maybe a next winter project.

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While in the USAF I worked on Jet Engines for C-130's (In left Pic a C130 is Air Unloading an Army Tank) and B-52's (In Right Pic of B52 that's a School Bus in Lower Right)

Do you ride in a lot of deep water NJDale?

My quads dont spend a lot of time in water, still there are wetter rides than others. I have always thought of making a air box for the UNI Pod I run, now you got me thinking about something like you did. Mounting the filter to the box not in it.

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07 Jetmoto 250 Sport
07 90cc Mini Ute
06 Jetmoto 200 Enduro
06 Jetmoto 200
06 Jetmoto 150
06 Jetmoto 125
04 Yamoto 150
01 KTM 400 EXC
92 WR 250
91 CR 250
88 YZ 80
85 CR 500
83 XL 600
82 XR 200
79 XR 75
79 Odyssey
73 Bultaco 360
71 Rickman Montessa 250
70 Rupp Enduro
69 Honda 50

MWQ - No I don't usually ride in water; however, you never know what the next bend in the trail will bring (part of the fun) and I REALLY hate to turn around and go back an hour or two !!! The biggest thing that I did to waterproof was to remove the harness / paint two coats of liquid electric tape on the back side of each connector, letting them dry / start at the white plastic and wrap back toward the incoming wires for about 4" / fill each female white connector with di-electric (silicone) grease / attach any black boxes and start wrapping the end of the box with electric tape and go back around each white connector and down the harness about 5". The only thing better would be MIL screw type connectors.

From what I read - 95% of the problems that people have with their quads is either fuel or electrical related. Totally waterproofing ( ie corrosion proofing) the harness & black boxes fixes almost any potential electrical problems before they happen. A good decent size fuel filter and good hoses pretty much protects the fuel system (except for water - add a little dry gas once in a while).

I'd rather work on it in the garage instead of on the trail !!!

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While in the USAF I worked on Jet Engines for C-130's (In left Pic a C130 is Air Unloading an Army Tank) and B-52's (In Right Pic of B52 that's a School Bus in Lower Right)

Replace your Chinese Paper Air Filter for 20% to 25% more power.

Last year I got (2) 250 cc (239 cc actually) and (1) 110 cc Chinese Quads. The 110 cc had the regular front air box and 5" x 7" oiled foam air filter. No Problem - was able to get a relatively good combustion mix as evidenced by the spark plug read.

The 250's came with the performance "Round Tapered Paper Cone type filer" - no airbox. No matter what I did, I could NOT get a good burn color on the spark plugs of both ATV's. It was always way too black, even leaning it out to the point that the quads either would not run or start. The Chinese paper cone filter looked fine - hold it up to a light & the light shone right thru it. They both would start right up and seemed to run OK, it was just that the plug was too black (rich).

I suspected the filter wasn't right and last winter built a home made air box with a Fram paper air filter (see my post under "Raceway"). After installing the new air box and filter, neither one would start except with a shot of either - OK, they had been sitting all winter and I had replaced the gas filter & hoses - no big deal, maybe air in the fuel line, etc.

This weekend at 70 degrees and only 3 or 4 days of not being run, neither would start. So, I started messing around with mixtures again and guess what - If I backed out the Idle / low speed mixture screw ¾ of a turn, they both started right up and idled well. (3/4 of a turn RICHER is a LOT !!!! ) So, that Chinese cone type paper air filter was causing a BIG restriction to the inflow of air to the carb.

I went out today to "play" in the sand / gravel pit and WHOW !!! All of a sudden, by the SOP Dynameter (Seat of Pants) it had a good 20% - 25% more torque and horse power. Boy would it climb hills, just spinning the rear wheels like crazy (I also have a 14 tooth front gear with a 50 tooth rear gear - 3.57 ratio). Me at 230#'s, just doing donuts with 3 to 4 complete revolutions !!! (got dizzy after 4 and stopped) (after all, I am 60).

So, If you have a Chinese paper type air filter - GET RID OF IT !!!. Get something made in America and be prepared to richen up the idle / low speed mixture screw. And, make sure that you hold on tight !!!

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While in the USAF I worked on Jet Engines for C-130's (In left Pic a C130 is Air Unloading an Army Tank) and B-52's (In Right Pic of B52 that's a School Bus in Lower Right)