Change the filter or no?!?

[katlover]

I have a 2005 750 Kat. I just dropped her off at the dealer for the 600 mile service. While she is there they are putting on a scorpion slip on. I have been told by many to put a K&N filter in her. I am not trying to make my kat faster I just want the sound. The dealer told me that K&N filters will let a lot more dirt in, and being surrounded by corn I can understand this. I was wanting to know, since I am not trying to readch the max possible HP (yet) should I replace the filter with a K&N? Please let me know why also. I can look at yes and no all day. I would like some backing on the reasons. I have gotten some great responses on other posts. I hope I can learn more about the filter here. Thanks everyone!!

[Anonymous]

For cost reasons I wouldn't do it until your stock one is used up. The K&N doesn't change the sound of your bike from my experience, not unless you put a jet kit in and use the larger K&N donut....

Just keep your stock for now, it sounds like you just got your bike anyhow, so ride it a while, and read up on it more to see what you ultimately want for your Kat.

[stevnmd]

Normally, I would suggest not replacing the filter with a K&N. Paper filters provide more than enough air flow.

However, the Kat's a strange beast, with a small air opening on the base of the filter itself which is the air inlet.

Get a hole saw. Open up the air inlet hole to about 2.5". Your paper element will flow plenty of air, and you'll still provide a larger air inlet that way.

Oh, and this assumes you're going to run a jet kit...

If you're not rejetting, definitely do not go with the K&N. There's absolutely no reason to. Your bike runs lean as it is. The K&N would just make it worse...

[The CyberPoet]

I'm with the general advice of not switching.

(A) The OEM filter really does filter better than the K&N will, especially as the months and miles rack up. The K&N filter relies on an oil coating as it's primary way to trap particles; the OEM filter actually screens the air through a layer of paper, followed by a layer of cotton batting, followed by another layer of paper. The hole sizes in the OEM filter are significantly smaller than those in the K&N.

(B) I do not recommend opening up the airbox or airfilter opening on the 98+ Kats in general. All the 98+ jetkits on the market are designed to work with the OEM filter and that OEM filter design flows enough air to balance anything up to a (theoretical) stage 2 jetkit -- I say theoretical because at this time only stage 1 jetkits are offered for the 98+ from any vendor I'm aware of.

(C) Enjoy your new can. Ask the tech to stick an exhaust gas analyzer into the tailpipe afterwards to ensure that your fuel-air mixture hasn't gone too lean from the modification (it'll take him all of 5 minutes to determine whether it has or not; odds are that it hasn't unless your bike left the factory particularly lean to begin with).

Cheers
=-= The CyberPoet

[katlover]

Thanks for your help. I'll ask about that exhaust gas analyzer also. Thanks again

[SweetLou]

And don't let them tell you that you need a Stage 1 Jet kit for a slip on!!!

I had a shop tell me that, and they had even already ordered it for me. I then proceeded to get into a argument with the shop, and picked up my bike from them!!!

Stay away from The Hitching Post Motor Sports in South St. Paul MN!!!!

[AkBigN]

Yeah the slip on shouldn't really effect anything but the sound. I can't see you needing a jet kit for that.

[katlover]

They told me I wouldn't need a jet kit, but the head mechanic there told me that he might adjust the "needle", something about the carb so the gas is more lean or less. He said Kats typically come out of the box a little lean. He sounded pretty honest to me. Does anyone know what he is talking about though?

[Anonymous]

He's right.

[The CyberPoet]

They told me I wouldn't need a jet kit, but the head mechanic there told me that he might adjust the "needle", something about the carb so the gas is more lean or less. He said Kats typically come out of the box a little lean. He sounded pretty honest to me. Does anyone know what he is talking about though?

Yes, he seems to know what he's talking about. It's not uncommon to shim the needles (i.e. - add a small washer under each one) and turn the pilot screws up a little to richen up the mixture, especially if you added any aftermarket products that might cause the mixture to go leaner than stock due to high through-put of the air/exhaust. The important part is that it get checked with an exhaust analyzer so it's definitively known whether it's lean, how lean, and whether the adjustments (if any are needed) helped or hindered.

Cheers
=-= The CyberPoet