K&N air filter

Cobbster · Post by **Cobbster** » Sat Dec 01, 2007 10:47 am

Hi all,
I,m doing my 12K service soon and I was thinking about replacing the air filter with a K&N one. What I would like to know is with the increase in air flow, do I have to alter the fuelling of the bike?. I realise this is a common upgrade for the 11S but I just wanted to check before parting with my hard earned.

Thanks, Cobbster.

P.S. Evil Knievel RIP

winger · Post by **winger** » Sat Dec 01, 2007 11:16 am

Bit like tyres, chips v PC everyone has their own take on K+N's,do they give you any more power??,i doubt it,what i do find they improve throttle response and that goes for any bike i've fitted one to,BUT!!! the S filter is a shit design,all the crap that goes along the intake and then just lies on the top filter just making things even worse,there have been times i've taken my K+N out and wondered how the hell the motor was even breathing.
The option particulary as the dollar is so crap and thats the SJ filter,cheap it ain't and as i've recently found out can collect shit with the best of e'm,but all the serious rubbish that comes down the induct drops to the bottom.
Re,does the fuelling need doing,yes and no,i used mine open pipe/SJ filter for 12 months or more it was fine,it just ran better with a PC on it.

sandbar · Post by **sandbar** » Sat Dec 01, 2007 11:59 am

My understanding with the standard K&N is that the filter element does flow better than the OE one, but the plastic surround is (unnecessarily?) bigger so the actual cross sectional area being used by the air is smaller.

The net result is an airflow that is uncannily similar to the OE paper filter!

Chris is right (of course

) the S&J Power filter is the way to go!

sandbar

QED · Post by **QED** » Mon Dec 03, 2007 9:47 pm

sandbar wrote:My understanding with the standard K&N is that the filter element does flow better than the OE one, but the plastic surround is (unnecessarily?) bigger so the actual cross sectional area being used by the air is smaller.

The net result is an airflow that is uncannily similar to the OE paper filter!

Chris is right (of course ) the S&J Power filter is the way to go!

sandbar

Hi where can I get details of the S&J Filter?

r550s · Post by **r550s** » Mon Dec 03, 2007 9:58 pm

san jose bmw in america - the product is called a powerfilter. It's a oval/round k&n, with an adaptor to fit it into the existing airbox. The advantages are A: much bigger filter area & B: the filter medium is vertical - so the crap doesn't just land on top of the filter medium. The adaptor (which is what you're paying for) is a milled aluminium replacement for the original airbox top. Rumour has it that the k&n that it uses is actually a stock part for an earthmover (v. appropriate!). Fuelled by this (and a lack of money), I went through the K&N catalogue & ordered a big cylindrical air filter - then I adapted the OE airbox top to fit, and glued it together. Val, Peter, John & Shep would've been proud. It works.

Boxered · Post by **Boxered** » Mon Dec 03, 2007 10:04 pm

Only available from sjbmw
http://www.sjbmw.com/parts.asp?searchty ... 0Treatment

Definatley recommended, and with the $/£ exchange rate right now, never been cheaper!

Steve

QED · Post by **QED** » Mon Dec 03, 2007 10:21 pm

r550s wrote:san jose bmw in america - the product is called a powerfilter. It's a oval/round k&n, with an adaptor to fit it into the existing airbox. The advantages are A: much bigger filter area & B: the filter medium is vertical - so the crap doesn't just land on top of the filter medium. The adaptor (which is what you're paying for) is a milled aluminium replacement for the original airbox top. Rumour has it that the k&n that it uses is actually a stock part for an earthmover (v. appropriate!). Fuelled by this (and a lack of money), I went through the K&N catalogue & ordered a big cylindrical air filter - then I adapted the OE airbox top to fit, and glued it together. Val, Peter, John & Shep would've been proud. It works.

Hi thanks for the help. Can you remember what part no the K&N was?

winger · Post by **winger** » Mon Dec 03, 2007 10:34 pm

K+N 042A6

r550s · Post by **r550s** » Mon Dec 03, 2007 10:43 pm

knew you'd ask that! can't find the receipt straight away - how about I take it out and post some photos & dimensions? - it's a standard K&N part, cost 25 quid or so. I used it becasue I couldn't bring myself to pay yet more import duty on a SJBMW item after shelling out import duty on the induct (Lennie recommends that you fit a powerfilter to get the best out of the induct) It works okay so I kept it.

QED · Post by **QED** » Mon Dec 03, 2007 10:47 pm

winger wrote:K+N 042A6

Cheers. Ill be taking the bike apart for its winter service, clean and fiddle.

What I thought about last year was a bit blue peter too. The most restrictive bit seems to be the part where the schnorkel nips up where it curves through 90 degrees. Was thinking about cutting out the inner surface of that and replace it with a piece of alloy or plastic alloy sheet bonded using flexible sealant. Im new to this site so Im sure someone else must have tried this?

r550s · Post by **r550s** » Mon Dec 03, 2007 10:51 pm

re the K&N part ref. posted by winger - is that the actual item that SJBMW use? nice work! The blue peter version that I did is probably a different K&N - it was a oval/cylindrical item, that just squeezed nicely into the oval-shaped hole in the OE airbox top. What a cheapskate!

sandbar · Post by **sandbar** » Mon Dec 03, 2007 10:52 pm

winger wrote:K+N 042A6

When I bought one it was E-4450 - and is only available from the U.S.A.(unless you want to wait ages for a K&N stock order to arrive in the UK by paddle boat)

If I remember rightly the number 042A6 is the moulding number of the rubber end moulding

sandbar

QED · Post by **QED** » Mon Dec 03, 2007 10:54 pm

r550s wrote:knew you'd ask that! can't find the receipt straight away - how about I take it out and post some photos & dimensions? - it's a standard K&N part, cost 25 quid or so. I used it becasue I couldn't bring myself to pay yet more import duty on a SJBMW item after shelling out import duty on the induct (Lennie recommends that you fit a powerfilter to get the best out of the induct) It works okay so I kept it.

Cant ask you to take it out thats too much hassle. Is the induct carbon fibre?

r550s · Post by **r550s** » Tue Dec 04, 2007 8:00 am

It's no hassle - I'll post some pics this week. The K&N catalogue is divided into specific-fit bespoke items (e.g. the 1100s OE replacement), and a vast range of cheaper 'standards' - for the blue peter contigent. From Sandbar's comment, I'd guess that the SJ powerfilter uses a hard-to-get bespoke item (cos it was the right shape for what they had in mind) - maybe the 'earth-mover' thing is true! The powerfilter is still a lovely-looking item - I was originally going to machine my own copy, but then I found that the standard-list K&N that I'd ordered could be just stuffed into the OE airbox top, job done. I like the look of the sj powerfilter - but I do wonder if there's a bit of 'incorporated value' in there!

r550s · Post by **r550s** » Tue Dec 04, 2007 8:21 am

re. your query over the pencil-shaped indent in the OE snorkel: Before I ordered the induct I read as much as I could find on the Pelican board. There was suggestion (from the induct nay-sayers) that the OE snorkel is tuned in some superior way, and the indent is part of that. Whether the 'tuning' was real, or for power or induction noise, seemed to be a matter of questionably-informed debate - but that's pelican for you. Have to say I was none the wiser... until I bought an induct.