Air filters - Which brand's the best?

While on the subject of filters ... I'm toying with the idea of installing a K&N 'air' filter element.

My questions are:
1 ... Will using a K&N require any carb adjustments?
2 ... I realize I won't get the air filtering quality from a K&N, however, could the reduction in particle filtration efficiency harm my bike in any way?
3 ... Is any increase in performance that I'd possibly gain from a K&N worth the extra money spent?
4 ... Is there any real gain in bike performance or is it all just an advertising hoax?
5 ... If a K&N is not the way to go and no modifications are to be made to the bike, what filter brands are available (other than those offered at Z1 Enterprises) for a stock '79 KZ650 with a KAWI Air Cleaning Element OEM 11013-1006 ?

The information provided in the link below which a previous post provided makes me wonder. Except for exceptional air flow of course, the K&N was rated worst in all testing categories. In seeking performance I don't want to place my bike in harms way.

home.usadatanet.net/~jbplock/ISO5011/SPICER.htm

Post edited by: BeeGee, at: 2005/10/13 21:42

a few years ago I saw an article in a car magazine that put diff. air filters on an airflow beanch, airflow was as good on a $3 K mart filter as the K&N "when new" how ever with some use the K&N would out flow the paper filters a small amount. the dirtier they got the better the K&N looked, maybe because it didn't trap as much dirt, I don't remember for sure, but you can clean and reuse the K&N!

As I do on my truck fleet, I have been monitoring the silicon content of my bike's used crankcase oil at oil changes to determine if the K&N filter was allowing excess dust into the engine. The test results are showing about 6-8ppm silicon which is very little. I ride mostly on clean paved roads. When I installed the K&N airbox filter my gas mileage increased from about 45mpg to 53mpg on a typical 200 - 250 mile day ride, and I didn't have to rejet as the engine ran fine with both types of filters. I would never use a K&N in offroad or dusty conditions but it seems to work fine when riding on paved roads.

Oldcoldankles,

Your analysis sounds interesting. How do you actually test the oil? Can you post details. This is good stuff.

Many fleet operations use contract oil analysis places to check their oil. They don't rely on old wives' tales to make their air filter, oil filter and oil buying decisions as we seem to do in the motorcycle community. You can take in oil samples and get them tested but it is pretty expensive for a private citizen testing one vehicle...

I talked to K&N about the results of the air filter tests noted in the link provided and they very much dispute them...

As far as WHICH filter to buy, I think all are effective when new. If you change a paper element often, then you should be fine and dandy as far as engine protection goes. The advantage of a K&N is that you can clean and reuse it. This leads to savings over time. UNI filters are also cleanable and reusable and less expensive than K&N.

As far as performance goes, I believe a drop in K&N flows more air than a stock paper element. I have confirmed this time and again when rejetting on my test bikes. I bump up the size of the main jet when using a K&N over a stock paper filter by one size... This means more airflow. I haven't done anything using UNI filters so I can't compare apples to apples but I did use sock type UNIs on a Vulcan with twin carbs and they flowed as well as the K&Ns they replaced based on seat of the pants feel.

Which filter to buy? Most motorcycles are operated for about 1-2K miles per year. Emgo pods will work fine for a number of years. If you ride 10-15K miles a year, you may need to swap them out during the course of a riding season if you live where it is dusty so K&N or UNI filters will look better from a dollars and cents standpoint. You have to look at bike use to make this determination.

Ever wonder why bike magazines don't do heads up testing of air filters, oil filters or oil? Only seen one test of oil and it was synthetic vs dino and I believe it was MCN that did the test (about a year ago?).

oldcoldankles wrote:

As I do on my truck fleet, I have been monitoring the silicon content of my bike's used crankcase oil at oil changes to determine if the K&N filter was allowing excess dust into the engine. The test results are showing about 6-8ppm silicon which is very little. I ride mostly on clean paved roads. When I installed the K&N airbox filter my gas mileage increased from about 45mpg to 53mpg on a typical 200 - 250 mile day ride, and I didn't have to rejet as the engine ran fine with both types of filters. I would never use a K&N in offroad or dusty conditions but it seems to work fine when riding on paved roads.

Showing that large of a mileage increase tells me your old filter was badly plugged up and needed replacement.
IMHO K&N's are not worth the cost. Buy stock and change the filter about every 10 thousand or two years.

Showing that large of a mileage increase tells me your old filter was badly plugged up and needed replacement.
IMHO K&N's are not worth the cost. Buy stock and change the filter about every 10 thousand or two years.[/quote]

What we do on the off road fleet is use precleaners and change the air filters by restriction indicators ie when they reach 20 inches vacuum pulled by the turbos. If you change the air filters too frequently you get less effective dust protection as a new filter allows much more dust through than an older one, and too frequent air fliter changes can hasten the dusting out of your engines in off road conditions. As Walt does, I also prefer paper element filters but wanted to see how the K&N performed, as the drop-in elements are kind of scrawny and my Corvette also has a K&N.
My fleet used oil analysis is done by Finning Caterpillar in Vancouver and I am gathering together some data on the results which I will post in this forum. I wanted to see the effects of the clutch and tranny sharing the same oil as the engine:)

Wiredgeorge - If I don't "bump up the size of the main jet when using a K&N over a stock paper filter by one size..." are there any negative repercussions? Will I still note a benefit in performance from the increased airflow a K&N provides?

Am I correct in assuming by not bumping up the jet size - I will not reap the 'full' benefits of a K&N?

Bump!

I was poking around the K&N website today and they claim improved airflow, increased fuel mileage and horsepower (although they refrain from saying how much) without the need for rejetting. In other words, borderline "too good to be true".

I found this thread to be about the best discussion of the subject in the new database. I find the discussion about dust very interesting since I do ride on gravel getting to the farm--at a minimum about 2 miles worth.

Given the fact that I'm not experiencing any performance problems, it looks like sticking with the OEM air box filter is my best bet. Thanks!

- Nate >>

you might skimp by without re-jetting but you wont get any real performance benefits if you do not re-jet.

Question is not which brand is best. Question is which brand best suits the application and use.

Looking at the referenced article the K&N provides the best airflow as long as it's kept clean. IMO it's doing what it's designed to do. Performance MC's need a lot of attention to be kept in top shape. Washing the filter now and then isn't a lot of additional work.

For a cruiser of commuter, the paper filter makes more sense.

-Duck