From K&N to OEM air filter

maximark

maximark

Joined
Aug 24, 2012
Messages
418
Location
Park Ridge, NJ
Bike
1994 ST1100
From what I've been reading about K&N air filters (not good things), I'm ready to switch back to OEM. I bought the bike with K&N and I have the feeling that if I switch, I should at least readjust the carbs... Eeh, is that right? Do I need to readjust or re-jet the carbs or just straight swap?
that would be something for Tech. day...?
 
I've been running the K&N filter on my '99 1100 for over five years... haven't experienced any problems with it. Of course, I do not use the outer foam sleeve which seems to restrict the air flow. I feel it is just a matter of personal preference. Changing to the OEM filter should not require a carb re-jet, maybe some minor adjustment if you have been running the outer foam sleeve. Would not hurt to revisit the carb sync after changing to the OEM.
Just my two cents worth... YOMV.
 
I just cleaned, inspected and oiled (lightly) my K&N yesterday. the bugs and trash were all on the dirty side, very clean on the clean side with no oily residue in the air plenum area (where the air goes in the throttle body) I find that a properly maintained K&N with Staintune exhaust gives me better performance and @ 4 miles more to the gallon on average. If you have total bone stock exhaust the K&N might not be an advantage due to the restrictive stock exhaust. If you don't properly maintain a K&N, your efforts are wasted and can be detrimental.
 
Well, there significant differences between naturally aspirated engines where actual carburettors still processing a mixture, and those with an EFI, where the engine gets teased with only tiny drops, squeezed out a pipette... ;)


Against the strong advise of my mech I'd tried a K&N many years ago...

Installed with the foam ring, as instructed in the manual, the ST wouldn't even idle properly... obvious asphyxiation...
Without the foam ring however, the spark plug electrodes turned snow white instantaneously!! :eek:

Since I wasn't in the mood for agonizing re-jetting procedures on a dyno with emission tester, which possible only ends in a waist of money and ruining the excellent setup and character of that engine anyway, the K&N quickly went to Ebay after not even 400km of use...
 
Thank you guys for your advice. She's running great actually, she did 99m/h the other day without sweat and idles good too. I was. Just wondering since all the fuzz about the mess in carbs but it comes out, that bottom line is PROPER MAINTENANCE. Thank you again
 
Odd how some have issues with K&N, either with or without the the collar, while others don't. I wonder what causes this difference.
Leaner jetted CA bikes vs east coast vs European carb setup?
 
Dunno, the US bikes have altitude control, no such thing in the Euro versions.
Also no charcoal box circuit for 'recycling' tank- and carb vent here.

Jetting on my 100HP model: mains #128, idle #40 (and already that ran fully lean with the K&N... but very nice pull above around 5800rpm...)

(IIRC does Germany/ED 98HP models... but that's due restricted carb boots with sligtly narrowed inner diameter)
 
Since buying my ST with 15,000 miles in Nov. 2008, it now has 87,000 miles. It came with a K&N and I have always used the K&N with no issues. Don't know why ?? but I decided to give a OEM filter a try this time. Will let you know what, if any is the difference!
 
DaveM said:
Since buying my ST with 15,000 miles in Nov. 2008, it now has 87,000 miles. It came with a K&N and I have always used the K&N with no issues. Don't know why ?? but I decided to give a OEM filter a try this time. Will let you know what, if any is the difference!
Click to expand...
That's what I'm thinking. I'm planning on taking top shelter off to fix some scratches so I might swap the filters to see...
will keep you updated.
 
Just installed a K&N on Lynne's bike before we went to Big Bend and back. I was running an OEM on mine. I fully expected her to have a measurable better gas mileage. Over the ~1600 miles the bikes used almost exactly the same amount of gas, just as they have been before with both using OEM filters. I expected a little better. I will keep up with this for awhile longer and see if the expected improved performance shows up.
 
K&N threads are like oil threads...everyone has strong opinions. My opinion is to steer clear of K&N. I've seen the results personally in my profession and won't run one. Most diesel engine builders won't warranty their engines if used with a K&N because they filter so poorly.

From a convenience point, I would much rather take 5 minutes to pop in a new paper when it needs it, than to have to plan ahead, wash the K&N, wait overnight for it to dry, oil it, and install it. As cheap as I am my time is still worth too much for that.

The suggestions that the reason some K&Ns filter poorly on our bikes is because they fit poorly is actually even more evidence pointing to a bad filter. If they can't even make them fit properly, I don't trust them to filter properly. I've seen dirty intakes on cages with good fitting K&Ns though. I have also seen lots of cages with very poor fitting K&Ns, which tells me either engineering or quality control is poor.

In the end...do what makes you feel good, and enjoy the ride.
 
As far as rejetting is concerned, I'd say read your plugs. They'll tell you what you need to know.

I stopped using K&Ns because I didn't care for the cleaning/oiling drill. I used them on my 750-4 K4, four small filters replacing the OEM and air box. The bike ran rich in the upper mid-range and top end. I read the plugs by maintaining speed for a mile or two, killing the engine and coasting to a stop with clutch in or in neutral. This gave me a better idea of what the plugs looked like at the time of a given throttle opening, not after motoring to a stop.

I raised the needles less than one notch (one notch was too much) and went up two sizes on the high-speed jet, as it was near-white, too lean for my taste. Much improved performance, much less milage at WOT, but a lot of fun to ride. And the sound of unsilenced air filters!

With EFI, I'd think that there is a range of compensation, how wide, I don't know. Your plugs should tell you what you need to know.
 
Ask someone who builds engines what they think of K&N Filters.
The folks that race with them, spend alot of time rebuilding engines after a few races.
Harley Mechanics love K&N filters. Its probably the main reason they rebuild motors every 40K miles or so :rofl1:
.02
 
When you say "style" are they paper elements that just look like a K&N filter, or are they oiled?
If they are in fact K&N oiled filters, its probably just a case of someone up the chain of command that read something and made a decision based on what he read
without knowing anything about the products....typical government spending, you know how much a toilet seat costs :rofl1:
 
No government spending here---all private owned , maintained and funded. They are K&N filters on a bigger scale, work great when serviced correctly and just like motorcycles--they don't when serviced improperly. The great thing about a helicopter that has been modified for these filter's is a door will open automatically and bypass the filter letting air into the engine. A light will illuminate on the master caution panel telling the pilot that a problem exist in the filter.
 
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