MotorCycle Air Filters On Mopeds?

David Lawson /

I need to get an air filter for my bike. I am wondering if I can get an air filter from a motorcycle shop. Would those work if I found the same size that would fit in my carborator? I read a few earlier posts about making your own filter but I dont understand how. If there were pictures it would help. Thanks alot. - David L.

Re: MotorCycle Air Filters On Mopeds?

Yeah well it would help if you provided more info ..

Like what bike and carb?.... orrr .. what diameter carb inlet ?

Motorcycle shops can order small Uni-Filter brand foam filters in small sizes... one may fit nicely on yours .. (you have to measure the air inlet).

Otherwise... can't you try one of the moped suppliers listed here for an original air filter for yours ? .. (new or used)

Other than that you will have to be creative...

... maybe use an old 'metal window screen and bend it to the necessary shape to fit over the carb inlet ... and then buy some 'filter foam' at an autoparts store and cover the screen with that ?.... then hose clamp it to the carb ?


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Re: MotorCycle Air Filters On Mopeds?

K&N filters work pretty good, most of the time. some bikes just don't have enough clearance between the frame and carb. I ran a K&N on the '99 tomos I had. removing the factory P.O.S. air box and putting a K&N was worth 5mph by itself. if you plan on any SERIOUS mods, consider a aftermarket filter.

Whatever you do, DO NOT RUN THE BIKE WITHOUT AN AIR FILTER. It takes a TEASPOON of dirt to totally RUIN an engine.

Re: MotorCycle Air Filters On Mopeds?

where did you get your K&N? would a local motorcycle shop be able to order it, or is there a retailer somewhere that has all their items in stock?

Re: MotorCycle Air Filters On Mopeds?

looks like those fancy air filters use the same open cell foam I use on sponge filters in my fishtanks so if all else fails, try the pet store.-Jim

Re: MotorCycle Air Filters On Mopeds?

Where the hell is the air box on a 84 Tomos Silver Bullet ?

Re: MotorCycle Air Filters On Mopeds?

K&N uses oiled gause mesh on a wire mesh. much more durable can be washed and re-oiled (will probably go longer between washings than the bike will last...

Re: MotorCycle Air Filters On Mopeds?

if carb is directly behind the head, probably between engine and frame.

Re: MotorCycle Air Filters On Mopeds?

i know where the carbs at but i see no air intakes or anything?

Re: MotorCycle Air Filters On Mopeds?

the intake manifold is the thing the carb is clamped on to that connects it to the engine. the side facing the back of the bike is where the breather clamps on to. since I can phisically see the carb, I can't tell you if you can use a K&N filter. If you can take a pic and post it, I could probably tell you.

Just ordered a UNI

I went over to the local Yamaha shop and ordered a uni filter. I decided not to go with the K&N, because my moped has been spitting oil out the intake a little. K&N's DO NOT like having other oils mixed with their filter oil.

Actually I have a K&N I should return to the factory- it shrunk. Not the filter cloth- the rubber. I'm the only person that I've heard of who had this happen. I never sent it back, because I didn't send in the original warentee card, and NEVER was able to get ahold of a rep. from the company.

I just don't want to blindly send it off and never see it again.

Before it shrunk, it flowed excellent, and fit well. After the shrinking, it, well, dosn't fit.

Re: MotorCycle Air Filters On Mopeds?

David Lawson /

I measured my carb and its about 2.1-2.2". If I get a Uni Air Filter does it hve to be that size? Or do they fit in anything? Im getting my bike to run soon and I want a filter on it.

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Re: MotorCycle Air Filters On Mopeds?

That looks like tha same carb as on my kinetic/vespa- kind of. Didn't a lot of people tell you to cut out a piece of filter that fits inside that large circle---

What I'd do is get a hose clamp that is the right size for the outer diameter, and get a piece of filter foam that is bigger than the outer circle.

Lay the foam flat against the big circle, and push your hose clamp over it. That would fit, if you didn't tear the foam, and it should work, without messing with the choke lever. Matter of fact I think I 'll try it with my vespa/kinetic--It just barely hit 30mph today.

You could use a lawn-boy filter at the hardware store- I think it's just a big square of foam, and it's pre-oiled.

The problem with putting a K&N filter on a bike like that is that it would stick out at least 3" and probably hit your front fender- unless you could find a pancake filter for it.

Re: MotorCycle Air Filters On Mopeds?

needs to be that Inner Diameter on the lip of the breather, and short enough

to fit in the space behind the carb...

they do make some filters 'flat' like that. while they would technically flow similar amounts of air (had both styles of breather, air flow also has a lot to do with direction and air speed too. (graduated from Nashville Auto-Deisel College in '93 with a 3.6 gpa, 3.9 in carbs and fuel injection...) the foam dissipates the air coming into the carb venturi, stalling small amounts of airflow. the clamp ons will let the air make more smooth turns into the carb venturi, allowing for a more atomized fuel/air mixture. meaning more power, meaning more speed.

have a Cosmo/Avanti/Garelli so I don't have to worry about hitting the fender, just the frame.the space behind the carb

Re: MotorCycle Air Filters On Mopeds?

Hey I took my engine off and found the intake and everything and took some pictures but i havent had the time to go get them devolped yet but yeah heres two pictures of my bike i have at the momment


Re: MotorCycle Air Filters On Mopeds?

that's the old style head. you'l probably have to go with the 'foam and wire mesh' filter setup because the clearance between the frame and the carb is so close. you still can upgrade you exhaust pie with a biturbo or some other expansion chamber style exhaust. upgrading the coil wire to a 8mm suppression design will help too. if you do the exhaust and breather mods, don't forget to rejet to a richer main jet in the carb. still looking to be in the 45-48 mph range if you do those mods...

Re: MotorCycle Air Filters On Mopeds?

I have a bi - turbo exhaust it only make my ped accel a bit faster and its top speed is now 29 to 30 instead of 28 thats all it did

and the back part of the pipe has air coming out of it where the copper part connects to the crome part of the pipe but yeah i have no idea how to put my new jets and sprockets in.


Re: MotorCycle Air Filters On Mopeds?

did you clean your exhaust port? what about the breather? If you don't let more air in, it can't push more out....

don't forget the coil wire either... when you do push more air and fuel thru the engine, you need as RELIABLE and powerful a spark as possible.

please forgive the crude diagram, but I think you can see what I'm talking about.


Re: Just ordered a UNI - Fred

It came in today... Now to make the a-dapter kit.

I was wondering should I use the uni filter oil or will any oil work- I've actually read that some people will use any "sticky" oil they can find.

Oiling a UNI

Me being the cheap bassturd that I am .. I would just use any motor oil .. don't put it on too heavy though .. there have been MANY bikes brought into dealers because .. "Its fouls plugs all the time! .. it didn't use to"

They soaked the filter with oil .. and it cuts off the air ..

.. just put some on and squeeze the filter to spread the oil around .. there shouldn't be any dripping or puddling of oil .. it should be wetted .. not soaked.

Re: Oiling a UNI

Well, I did get some filter oil.... It's really weird stuff. It's a really thin oil, but once it dries it get tacky and makes webs when you touch it and pull your finger away. I can see the advantage of using it. It was $6 for a can.

I only used a little, and wrapped the filter in a paper towel to squeeze excess off. I hope ther isn't too much oil in it. I'd have to clean it all out and make sure it's totally dry , and re- apply it.

Another plus- it's water repellent.

Thanks Fred

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