Jeff Kellogg
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What is the advantage of using an air box over just a K&N filter directly attached to the carb?
Air box versus K & N air filter
- Thread starter Jeff Kellogg
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brendonv
New member
K&N = more air flow = more fuel and air being sucked into the engine = more power. I dont think u would feel a noticeable difference with a stock carb and K&N. U really gotta get something like a mikuni if u want that if u wanna get the most u can out of the new filter.
As i said before, more air flow = more fuel being sucked in....... but to really accomplish that u need a bigger jet to allow for more fuel that is now being sucked in. If ur just gonna whack one on the stock carb, look at gettin a bigger jet (im not at all a pro on this so dont ask me about jet sizes, jrdragster is ur man in this department) otherwise u might be running to lean (aka, to much air, not enough fuel).
Hope that helps.
As i said before, more air flow = more fuel being sucked in....... but to really accomplish that u need a bigger jet to allow for more fuel that is now being sucked in. If ur just gonna whack one on the stock carb, look at gettin a bigger jet (im not at all a pro on this so dont ask me about jet sizes, jrdragster is ur man in this department) otherwise u might be running to lean (aka, to much air, not enough fuel).
Hope that helps.
Russ2251
AZUSA:Powered by LAWN-BOY
I think you maybe confused.
They each perform very different functions.
Airboxes do not filter air. Filters are used on airboxes.
Filters are a must. Airboxes are optional.
There are ongoing arguments as to whether or not airboxes do anything at all on small engines.
Theory is that airboxes have a "super charger" effect on a very small scale.
They vary in size according to engine requirements.
They each perform very different functions.
Airboxes do not filter air. Filters are used on airboxes.
Filters are a must. Airboxes are optional.
There are ongoing arguments as to whether or not airboxes do anything at all on small engines.
Theory is that airboxes have a "super charger" effect on a very small scale.
They vary in size according to engine requirements.
brendonv
New member
I think he meant with a filter. I was thinking he meant like what are on hondas. The plastic "box" with the filter element in it.
Ferrari motors15
New member
if you put a k&n and a mikuni you will win up to 1.5hp but this only work if you use the top of the line model(90$)
Kaptain Krunch
Pro Junk Collector
no u won't.
Kenny_McCormic
Kartless....
Forget both of them, get a dual stage UNI.
anderkart
Moderator
One big advantage to the stock type of air box like many Briggs or Honda industrial engines come with would be to help keep rain from saturating the filter. Another advantage is they tend to help silence the intake port kinda like a muffler does for the exhaust.
Some classes of kart racing require every karts K@N or Uni type air filter to be located in a track approved/race type air filter box to help silence the intake.
I used to ride a Maico dirt bike that had a foam type air filter clamped on the carb. The bike had a air box mounted in the frame right behind the carb that completly housed filter. This air box had its intake holes positioned to only draw in air from the under the seat area. My air filter tended to stay a bit cleaner than my buddy's bikes with open/unshrouded filters. This also kept my filter dryer when riding through water puddles, streams or in the rain. I thought it was a pretty good idea.
When I switched to an open air filter it was actually more of a worry than it was added power. I had to get an outerwears water repellent cover and it doesnt protect from fine dust as well (especially UNI). If you have an engine with an air box like the honda's, clones, and subaru's and all and want some extra air flow you can drill some holes in the front and on the sides. It obviously still wont flow like an open filter but it will be a little bit better. I think that's what Im going to do with mine. To racers its not really a problem, but if you just ride the trails you sometimes need to sacrifice some power in order to keep your engine and carb clean and safe.
anderkart
Moderator
I've used both K&N and Uni (each corectly cleaned and oiled) on a very dusty dirt oval kart track and found equal amounts of dirt residue stuck to my carbs bore that had obviously passed right through each of these filter brands.
If your serious about making either one of these filters work way better I'd suggest using a prefilter (or outerwear) sock that fits over the filter: http://www.outerwearsracing.com/ They truly help both of these filter brands to work way better.
Same with me. Ive found that UNI especially let bigger particles through. Ive been using a K&N with a UNI green (denser) prefilter since June on my 7hp Subie in some of the most dusty conditions Ive ever ridden in, and I havent found anything that got by it.
Ferrari motors15
New member
go on affordable go kart read the description of the mikuni carb and you will see
Ferrari motors15
New member
Kaptain Krunch
Pro Junk Collector
just by slapping a mikuni and an airfilter on there you won't gain 1.5hp you will have to modify the engine so that it can burn more fuel, which will create more power.
CoyCaller
New to go karting
It's funny you guys brought this up today.
I have been rebuilding a Honda gx160 for my kids' kart. I put a new crank, rings, and gaskets in it. I cleaned the carb and drilled the jet, removed the oil sensor, and the governor. I put it all together, minus the factory Honda airbox and it ran like a scalded dog. I put the airbox on and put it away. When the kids showed up, I told them how good the new engine on the gokart ran compared to the old 3.5hp briggs that was on it. They tried it and it ran very crappy, it was loading up.
Today I took the carb off and cleaned it and put it back on, minus the airbox. Once again, it ran fine. Put the airbox on and it fell on its face again. It needed more air than the factory airbox would allow. Even with the filter off, it can't get enough air to run properly above idle speed. I put the airbox on the engine and held the throttle open and force air into the intake and she cleared right up.
One you modify for more fuel the need for air increases and you have to keep the fuel/air ratio the same. The factory airbox is just to restrictive.
I see someone earlier in this thread mentioned drilling holes in the airbox. Hopefully you are not doing this between the filter and the carb because the results will not be good. Dirt and engines do not mix well.
I have been rebuilding a Honda gx160 for my kids' kart. I put a new crank, rings, and gaskets in it. I cleaned the carb and drilled the jet, removed the oil sensor, and the governor. I put it all together, minus the factory Honda airbox and it ran like a scalded dog. I put the airbox on and put it away. When the kids showed up, I told them how good the new engine on the gokart ran compared to the old 3.5hp briggs that was on it. They tried it and it ran very crappy, it was loading up.
Today I took the carb off and cleaned it and put it back on, minus the airbox. Once again, it ran fine. Put the airbox on and it fell on its face again. It needed more air than the factory airbox would allow. Even with the filter off, it can't get enough air to run properly above idle speed. I put the airbox on the engine and held the throttle open and force air into the intake and she cleared right up.
One you modify for more fuel the need for air increases and you have to keep the fuel/air ratio the same. The factory airbox is just to restrictive.
I see someone earlier in this thread mentioned drilling holes in the airbox. Hopefully you are not doing this between the filter and the carb because the results will not be good. Dirt and engines do not mix well.
anderkart
Moderator
If you put the stock sized main jet back in that carb you'd probably notice way less diference. (I was wondering if your air filter element is brand new or meyby its partially clogged/dirty?)
CoyCaller
New to go karting
The element is not new but I took the filter off and I was still not getting enough air. It wasn't getting enough air with the filter off.
I took the filter off and forced air into the box (just a little) with the blower on the air compressor and the engine ran very well.
I agree that if I put a stock jet into the carb the airbox would be sufficient but with the governor removed, I wanted more fuel to sustain the higher rpms. Since it is the kids' kart I will probably just put the stock jet back in as it is cheaper than the KN style filter and adapter.
I took the filter off and forced air into the box (just a little) with the blower on the air compressor and the engine ran very well.
I agree that if I put a stock jet into the carb the airbox would be sufficient but with the governor removed, I wanted more fuel to sustain the higher rpms. Since it is the kids' kart I will probably just put the stock jet back in as it is cheaper than the KN style filter and adapter.
Rickracer
RM250 Race Kart Driver
Generally, the bigger jet is something you do to compensate for freeing up the exhaust, (like a header). The pumping action of the motor will pretty much ensure it gets enough fuel, even at higher rpms, as long as it has some kind of filter. 
CoyCaller
New to go karting
Rick,
So, do you think the stock exhaust is causing my rich condition? Would a straight pipe cause the intake to pull more air?
So, do you think the stock exhaust is causing my rich condition? Would a straight pipe cause the intake to pull more air?
CoyCaller
New to go karting
Tired of waiting on you, Rick. :toetap05: I'm going to the shop to find out. I waited 12 whole minutes. LOL
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