ok, well i just realized the possibilities of what i can do with air intake, now i know some of you are tired of hearing about my 77 xr75, but can i put any air filter on it that fits? or does a certain amount of air have to be regulated? or does the carbuerator do it for me?
the second someone says itll be fine im gonna buy a k&n air filter for it
Get your K&N filter, it’ll be fine. There’s nothing magical about a car’s air filter; anything that can keep out dust and bugs will get the job done. Air management is handled by the carb.
Frankly, I don’t know why anyone would prefer a K&N filter over the OEM-type filter, but that’s your choice. It’ll work.
You do understand he’s talking about a 1977 75cc motorcycle?
So, what? It’s a 1977 Honda motorcycle. Still a gas engine with a carburettor. The carb does all the air-regulation. Run whatever filter you like. But run a filter. Dirt is the engine’s worst enemy. Do you off-road in a dusty area? A K&N is an oil-impregnated filter, and will get dirty faster. It is washable, but just requires more maintenance. Another idea is a foam sock that fits over the air filter. It is also washable, but doesn’t need oil, and will help keep the dust build-up down on the air filter. It’s been a while since I rode a bike, but a bike shop should have them.
Actually, I might put a K&N on a 75cc bike that is easy/cheap to rebuild. I certainly would not use one on an expensive auto engine.
how come?
Do an internet search on the filtering capability of K&N filters. There is evidence that they do not filter as effectively as OEM filters (at least in automotive applications). IMHO, the small reduction in pressure drop does not justify less effective filtering. There are also concerns with the oil from the filters carrying over to the air flow sensors on fuel injected engines.
I’ll second Craig on that. 
will i have to get my bike rejetted?