K&N Air Filter Question

I just bought a new yfz450 and the service guys told me NOT to put on a K&N filter. They said that the K&Ns allow small grit to get past which will grind off the coating on the valves and eventually cause them to fail. Supposedly they have just serviced a bike that had this problem.

It sounded a bit crazy and I love K&Ns but I don't want to blow up a new motor. Any experience on this subject?

Just put a twin air filter on it.

A lot of users on this forum have them with no issues.

Yep, I'm one of those owners that had premature valve wear due to using a K&N....your mechanic is right. Go with a TwinAir and Maxium FFT oil and you'll never see anything in your airboot past the filter. :applause:

I just bought a new yfz450 and the service guys told me NOT to put on a K&N filter. They said that the K&Ns allow small grit to get past which will grind off the coating on the valves and eventually cause them to fail. Supposedly they have just serviced a bike that had this problem.

It sounded a bit crazy and I love K&Ns but I don't want to blow up a new motor. Any experience on this subject?

Do NOT use a K&N filter for off road! They will also trap water, and will not allow your engine to breath creating a huge bog in power. I have seen this happen first hand.....

The truth is that K&N filters are better than foam, both in their airflow characteristics, and in their filtration capabilities IF they are correctly and thoroughly oiled, and because of how they are made, that's a big if. All you have to do is miss a spot. That of course is true of foam, but you cn squeeze foam and work the oil through. Not so with gauze.

As far as the water thing goes, I'm not sure that letting the water go straight through and into the carb is better than trapping it.:applause:

I've used K&N's for years without any problems but I do keep them cleaned and oiled well. Like most things I'm sure there is opportunity for user error which may explain the position the service guys have on them.

I've used K&N Filters for years Dirttracking where they get absolutely hosed with dirt. 10x more than what you a normal MX bike gets with the filter inside the airbox.

The biggest thing is keeping them properly oiled and cleaning them often.

I have K&Ns on the Banshee. I have just the stock foam on my YZ.

So I have been using Maxima spray on foam oil on both of them.

Is that right or should I get a special oil for the K&N?

If you mean Maxima FAB-1, that actually is made for gauze filters, and it's good stuff. Still, be sure it's oiled thoroughly.

Thanks for the advice.

The truth is that K&N filters are better than foam, both in their airflow characteristics, and in their filtration capabilities IF they are correctly and thoroughly oiled,

I disagree. K&N oil (and No-Toil oil also) dry out with time whereas the true petroleum oil based ones like Maxium FFT stay super tacky indefinitely. Go soak a rag, towel or piece of foam in either of these two types of oils and let them sit for a week, then go touch 'em and see which is still tacky. The K&N and No-Toil will be dry and stiff with no tack, whereas the FFT will be as gummy as day one.

Therefor unless you treat your filter every time just before you ride, you're not doing all you can to filter your bikes air because your filter oil has dried and hardened.

I disagree. K&N oil (and No-Toil oil also) dry out with time whereas the true petroleum oil based ones like Maxium FFT stay super tacky indefinitely. Go soak a rag, towel or piece of foam in either of these two types of oils and let them sit for a week, then go touch 'em and see which is still tacky. The K&N and No-Toil will be dry and stiff with no tack, whereas the FFT will be as gummy as day one.

Therefor unless you treat your filter every time just before you ride, you're not doing all you can to filter your bikes air because your filter oil has dried and hardened.

First, I never suggested using engine oil to oil any filter. Second, neither did I recommend No-Toil or K&N oil. In fact, the only oil I've said anything about is FAB-1, which is essentially FFT in a spray can. Thirdly, I don't see anything in the quoted statement concerning which oil should be used.

What I said was, K&N air filters can and do flow more freely than foam filters do in general, and, K&N filters actually filter better on the whole than foam, but only when they are correctly prepped. I also pointed out that the reason they so often fail in the filtration department is simply because it's so difficult to prep them correctly that people end up doing a bad job of it.

If I get time, I'll see if I can dig up a study that was posted some time ago concerning filter efficiency. It was posted to show that foam was better, but it actually showed the reverse.

BTW, I personally use foam elements and FFT.

Another good option for the K&N is the pre-filter outwear.

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