This may sound like a dumb question But here it goes...I was told that the simplest and cheapest way to get better performance out of a stock 2-stroke Polaris is to get a sir filter kit. I have heard about them but what exactly what are they talking about? I have a 300 express with the 2 piece pre filter and the big can filter down inside the filter box. Do I eliminate all of that for the air filter upgrade or just put the new filter in the Box?? And will I notice a little difference in performance or isn't it worth the trouble and stay stock??? Any info would be great!!!

 

Bosty,
Maybe what they are talking about is a K&N filter and Jet kit...
K&N's flow more CFM... and then you can re-jet for optimum fuel mixture. Thereby increasing fuel/engine efficiency.. and THAT is free power.

 

Hey Mud!! I Heard of the K&N Filter, But what is it?? Does it eliminate my filter box and pre filter all together?? Or is it just a filter that replaces the one in my filter box?? Another question Would I have to rejet to compensate the air flow or just adjust the fuel Mixture??

 

Bosty,
A K&N filter is basically like your stock filter and goes inside your airbox. There are "clamp on" K&N filters that replace the entire airbox.. Clamp on meaning that it clamps directly to the carburetor.. I wouldn't suggest the latter for a machine that sees mud/water... those are mainly for sport oriented machines.. but, back to what is a K&N filter...
It's physically the same demensions as your stock unit but with a twist. Instead of being constructed of paper and having to be thrown away when dirty, a K&N is constructed of cotton guaze.
It comes out of the box ready to use (pre-oiled) You can get the pre-filter for it also, which is similar to the blue "sock" on your stock one.
When this filter starts getting dirty, airflow actually improves.. (that doesn't mean roll it in the driveway first..hahaha)
When it becomes time to clean a K&N, all you do is remove it, spray it down with the K&N filter cleaner solution, let it soak, wash it out in warm water, and let it dry completely. After it dries, you re-oil it with K&N filter oil and re-install it...
The only no-no's are compressed air and beating it against something.(You shouldn't do that to a paper filter either) K&N filters seem to hold out the water when you screw up and sink it.. If you've ever tried to start an engine with a wet paper filter, you WILL appreciate a K&N..!!!!!
They guarantee K&N filters for 1,000,000 miles on automotive applications, and personally, I use them exclusively on everything I own that I can find one for..
If you buy a kit, it will come with the filter, pre-filter, care kit, jet kit, instructions.
As for re-jetting.. If it were a stock 4-stroke Polaris, you could probably get away without re-jetting.. I say this because it seems that most Polaris 4-strokes are set up "fat" from the factory.. BUT, being a 2-stroke, I would run it for a few.. then check the plug condition and re-jet as necessary.
Re-jetting will give you the best results.. and if you do any other mods...clutch, pipe, porting...etc... You WILL have to jet it!!..
Good Luck!!!

 

Does anyone know where I can get a K&N filter for a 2000 trailboss - 325 4 stroke??

What would it get me to install one, besides getting rid of that pesky paper filter ???

 

Bosty22: I've tried the K&N filter with the addition of an Outerware cover (kind of like a stiff nylon sock) as well as a foam air cleaner from UNI FILTERS. In my opinion the K&N had let a small amount of dust through as I found when I ran a slightly oiled white rag down into the rubber intake hose to the carb. I should have told you it has been extremely dry here in Nebraska where we ride and the dust is very heavy especialy on this particular weekend. I followed the manufacters cleaning and oiling proceedure and after doing so you could see a lot of small holes in the filter when holding it up to the light. This is when I went out a purchased the foam filter. It is a double design which has a outer foam that is more open so to speak than the inside filter which is very fine. These need to be oiled as well but so far have provided better protection in my environment. As far as performance gains I couldn't really feel any difference between the stock paper, K&N or foam. I ride a stock 98 Scrambler 400. These aftermarket filters fit into the stock airbox and can be cleaned and reused as long as you take care of them. I'm sure that rejetting and adding pipes and such will make hugh differences in power I've got to say I'm very happy with the way my Scrambler runs just the way it is. Be safe use safety gear when riding and enjoy the sport!

 

I noticed a substantial gain in throttle response on both my quads after switching to K&N air filters. I installed them on a 99 Polaris Sport, and my 00 Yamaha Kodiak.

 

You can buy them at your Polaris dealer. Cheapest price I have found, dealer or mail order, is about $32, or from the Polaris accessory catalog $29. I paid $29...