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View Full Version : Quick air filter question


racerdan24
12-28-2008, 09:15 PM
Twin air and Uni filters....Do they need a rejet or not ?
I have heard that Twin air you don't and Uni you do. If you run the stock box, lid etc and just replace the filter would it need the rejet? I am still confused over this air filter swap.
12-28-2008, 09:57 PM
Air filters normaly dont flow enough air over stock to need a rejet.
racerdan24
12-28-2008, 10:08 PM
Thanks Boris...That is what i thought....just wanted a second opinion
powermadd400ex
12-28-2008, 10:10 PM
if you run without a lid, yes by all means rejetting is necessary. but for the lid on, i dont think so.
rob_990
12-30-2008, 11:02 AM
no you shouldnt have to i just put a twin air on my dads utility and i didnt need to rejet.
Mustangous
01-01-2009, 08:39 PM
how would you know if it needed to be rejetted? would it run like crap or by reading spark plug?
racerdan24
01-01-2009, 08:46 PM
Probably both
Brauap
01-01-2009, 10:13 PM
You do not have to rejet the carb by running a UNI, Twin Air, ect. (foam) But if you run a K&N, you do because of the much added air flow.

You won't really notice a difference between a jetted carb and a non jetted carb with a K&N, it just helps the engine run to its fullest.

Like stated above, you do however if you remove the air box lid or add any sort of cover (aka K&N Powerlid, Outerwears Air Box Cover, ect.)
hornetgod13
01-02-2009, 02:39 AM
A UNI does have increased airflow over a stock filter. Going up one size on your pilot and main jets could not hurt considering Honda jetting is on the lean from the factory.
Brauap
01-02-2009, 08:44 AM
Originally posted by hornetgod13
A UNI does have increased airflow over a stock filter. Going up one size on your pilot and main jets could not hurt considering Honda jetting is on the lean from the factory.

True. However it isn't needed, like stated above, it can not hurt anything. If you are, just bump the poilet jet upto a 42, that had really helped my cold starting (& winter) troubles.
01-02-2009, 03:59 PM
i would never NEVER increase air flow without increasing fuel flow...a la a larger jet. twin air and unis do flow quite a bit more air than stock, therefore, they will, more than likely, need a re-jet so as not to be lean.

and the pilot jet only controls about 0to 25% of the throttle where you are hardly ever at, the main controls roughly 75% to full throttle, where you spend most of the time...

read the faq on jets and jetting as well as reading plugs to help you out...the site to go to is: http://www.jetsrus.com/main_page.htm