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1998 ST2. Can't seem to make heads or tails from using the search feature here.

Anyone have a strong opinion one way or another regarding using a K&N on a 1998 ST?

I've used them on bikes before and on one occasion found a very noticeable difference, for the better.

Seems some here are saying that too much dirt gets collected with them though...
 

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I have one on mine, I keep it clean and have had no problems. I have read good and bad opinions on this and other forums. Since I do not ride in a dirty environment I have not noticed any dirt getting by mine. Keep it oiled and it will last a million miles. I am sure I will get flamed for that:D
 

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Over the years, I've acquired two K&N filters for my ST2 through various means. I sold one and the other is....sitting in a box on the floor. I just prefer to use the OEM paper filter. I do have a K&N on my Harley, though, and it seems to have done the bike fairly well for over 80k miles.....I just can't bring myself to put one on my ST2, for some reason.
 

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Seems some here are saying that too much dirt gets collected with them though...
The paper filter filters better and breathes just as freely. It is also inexpensive and MUCH more convienent. Who wants to clean and oil an air filter? The oiling is easy but the cleaning is messy and takes time that I would rather spend riding.

I don't need all that dirt in my engine either.
 

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Mine had a K&N when I bought it and it still looks new. I haven't had to clean it yet after 7,000 miles. I've had the same one on my Airhead for 25 years and it still looks new. I've spend a few minutes cleaning it a couple of times so it's been worth it for me.
A very dusty environment might require more maintenance though.
 

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I noticed that mine makes a whistling sound since I put it in that is pretty annoying.
 

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I run K&N's on all my auto's and my ST4. Everytime I put one a vehicle I've noticed a milage gain and usually a small power gain. One has been on my wife's car for 70,000 miles and I do not see any sign that they do not filter as well as any stock Air cleaner. I do live in a dusty area and have never had a problem with the filter plugging or having any problems cleaning it. The cleaning kits are very easy to use and never seemed to be a hassle to use..... Just my 2 cents worth.
 

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I use one. Not a K&N, but the BMC brand that Ducati includes in its air box kit. I don’t consider an air filter a performance item. More of a convenience item and a durability issue. Yes, online tests you can Google show paper filters flow as much air as an oil and gauze filter. The thing that some tests also show is paper filters flow less air as they become dirty where the oil and gauze filters keep flowing as much air as new. Something to do with how dirt collects in the oil rather than becoming embedded in the paper as I remember it. I clean mine at each valve check interval, which is probably more than it needs to be. I will "knock out the big chunks", if needed, whenever I lift the tank. It's also one less item to buy come maintenance time. Not sure what a paper filter costs for these bikes (never bought one), but buying them would likely wind up costing more than a K&N over the life of the bike if you ride a lot. I had one in my old SS for almost 48K and I have had the one in my current bike for almost 25K.

Comments keep coming up about poor filtration. People have coated their air boxes with oil and have said they find a lot of grit inside. This is proof positive to them that oil and gauze filters do not work as well as a paper filter and people should stay away from them. I have coated my air box with filter oil and did find some grit, but nothing I would consider a huge amount.

I do not mean to be challenging here, just genuinely curious. Also this will be the 3rd time I have asked this question in this forum on a thread like this.... No answer yet!

Has anyone run the same test (coating the in side of the air box with oil) and found less grit inside the air box while using a paper filter as compared to the gauze filter, proving at last, that paper filters do in fact filter better? This of course would have to be done in the same riding environment to be valid.

Use them, or don’t. I don’t think you can go wrong either way. Just be sure to not over oil the filter! I did that the first time I cleaned the filter on my old SS. I had filter oil dripping from the air box drain!
 

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Mine had a K&N when I bought it and it still looks new. I haven't had to clean it yet after 7,000 miles. I've had the same one on my Airhead for 25 years and it still looks new.
Yeah, that's because gauze filters are really only good at filtering the big stuff like bugs, leaves and airborn seeds. Because much of the road grit goes right through into your engine they do stay looking clean longer. Even when well-oiled they still don't seem to hold the dirt back.
 

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I have used K&N for the last 25,000 Mls and mainly prefer it because I clean & oil every 3000Mls which keeps it clean and efficient (I.E.Filters and passes air efficiently for the duration) Cost wise I would got through 8 paper elements @£ 8.00 each (£ 64.00) based on a recommended interval of 6000 Mls by which time the paper filter would not be flowing air as efficiently or 16 costing £ 128.00 to maintain the same efficiency.
Cost of the K&N off Ebay was £ 10.00 alongwith Cleaner & Oil adding another £ 15.00 but these items are still good for a long time yet. (Cleaning takes minimal time as I combine it with general maintenance)
Good or Bad , who knows , I'm happy..........:)
 

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Yeah, that's because gauze filters are really only good at filtering the big stuff like bugs, leaves and airborn seeds. Because much of the road grit goes right through into your engine they do stay looking clean longer. Even when well-oiled they still don't seem to hold the dirt back.
I think the operative words here are "seem to". My engine is doing fine with at least 130,000 on the K&N filter so far.
 

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If and when you run with a open air box the gauze filters are not affected by water, where as when a paper filter gets wet it becomes restrictive. Even when you dry a paper filter after it has been wet it is still screwed as the paper swells when wet and the pores stay closed after drying, I experienced this issue with a previous bike and cured the problem with a [email protected] replacement filter. As far as filtering ability, the paper filters will be better but seriously I have been using gauze filters for years, all my bikes have high mileage and all my bikes have strong healthy engines! If you want to use one go for it - make sure that the filter is seated properly and then move on.

Jerry
04 ST4s
 

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RE: Has anyone run the same test (coating the in side of the air box with oil) and found less grit inside the air box while using a paper filter as compared to the gauze filter, proving at last, that paper filters do in fact filter better? This of course would have to be done in the same riding environment to be valid.

Yes, I did the test with a fresh K&N, found some grit in the K&N oil that I applied to the inside walls of the airbox (below the K&N element).
Then I did the same test using a paper element after cleaning out the oil/grit, and then re-applying clean K&N oil below the paper filter. I did not detect any gritty feeling in the oil after a season of commuting and sport riding using the paper element. Run the test yourself and decide...
 

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Yes, I did the test with a fresh K&N, found some grit in the K&N oil that I applied to the inside walls of the airbox (below the K&N element).
Then I did the same test using a paper element after cleaning out the oil/grit, and then re-applying clean K&N oil below the paper filter. I did not detect any gritty feeling in the oil after a season of commuting and sport riding using the paper element. Run the test yourself and decide...
Thanks for the answer. I doubt I'll take the time to do the test myself, as I'd have to buy a paper filter and run it for a period of time. I don’t care to do either. I am comfortable with the filter I have been using. The small amount of grit I found in my air box after coating it with oil did not seem excessive to me. In fact, maybe coating with oil aids in the filtration process! I only made the comment because, except for you, people make the claim that K&N type filters are to be avoided because of the grit in the air box but can never follow up with proof that a paper filter would fair any better because they never tried. Just curiosity on my part.

I assume you are sticking with a paper filter?
 

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I only made the comment because, except for you, people make the claim that K&N type filters are to be avoided because of the grit in the air box but can never follow up with proof that a paper filter would fair any better because they never tried. Just curiosity on my part.
I have done the same test multiple times. I went back to my freshly oiled gauze filter thinking it was a fluke but I got the same result again. I have 46,000 miles on my ST4s with about 8,000 miles on gauze filters and the remaining miles with paper filters. Before I leave on a multi-day trip I oil the gauze with K&N filter oil according to instructions and also smear some clear grease around the clean airbox as well as the rubber seal around the perimeter of the filter. Both times when I returned the coarseness of the grit in the airbox was shocking, it felt like beach sand.

I follow the same procedure with the paper filter (omitting the oiling of the filter itself because it is paper) but there is no grit in the airbox when I return (but the pleats are full of sand, seeds, dust and dried insects). The grease inside the airbox has turned a slightly darker color after 6,000 miles but whatever gets past the paper filter is too small to feel so it remains smooth and greasy feeling, not sandy and gritty. I knock out the sand/insects from between the paper pleats and vacuum the filter and re-install. They are still serviceable after 12,000 miles but are so inexpensive I pop a fresh one in there in that point.

I run an open airbox and have ridden through considerable rain but on the ST's the filter is well protected by the fairing and tank so it never gets wet enough for me to worry about. I never see any water stains on the paper filter or any wrinkling.

I can't imagine why anyone would mess with washable filters on an ST when the paper ones are so demonstratably superior, inexpensive and easy to maintain.
 

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FWIW, buy the K&N, do the test yourself. If the KN pisses U off, you can alway resell it easily!
 
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