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K&N filters for flatslides

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  • 4 months later...

Gotcha - back to front purchase! So used to hearing of us buying from the Land of Uncle Sam, didn't think Uncle Sam needed assistance from the Motherland occasionally LOL!

I'll measure a set of ram pipes a bit later when i'm in the garage, but think 52mm dia is about right.

EDIT : Just measured and 55mm dia is the size required.

Edited by Gixer1460
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Thanks, I'm guessing these are the ones to go with then.



This is what's currently on the bike and they're old and the rubber is cracking and I've never really been all that sure of how well they worked. And here's a photo of the current state of the bike, because I know how much everyone likes project photos.



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  • 4 weeks later...
49 minutes ago, Reinhoud said:

ask Buzz from Dynoman Performance in the US, he has a cheaper version of the K&N, just as good, half the money

Problem with K&N's or similar filters is non compatibility with Ram pipes - the foamies are about the only thing that will stretch over!

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  • 2 weeks later...

http://www.ramair-filters.co.uk/shop/motocross/sock-filters-motocross/2-x-twin-inlet-carb-socks-5/ would probably be about right if you want 'pods' - centres are a bit off but not a biggie. I think i'd fit the ram pipes into the filters first then fit all to the carbs because the outer lips of the stacks are pretty close together when on the carbs and I think foam rippage would occur fitting insitu! Ram pipes come in short 25mm, medium 50mm and long 70mm - select on where you want the benefit - short = high rpm, long = lower rpm.

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  • 2 weeks later...
48 minutes ago, Swampy said:

your right about the length of the stacks. but who does them at the best prices.


Have a look at Gsxr 600 k model airboxes. The rubber stacks fit flatslides with a nice lip to hold the filter socks on. The 750 boxes are similar but less common. I have bought them for £10 Inc delivery on the bay. You will need 2 airboxes though as the stacks are not all the same length. 

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will do sounds like a good idea.

i was informed by a close friend of Leon Moss. he of LeDar fame. that the flat spot suffered is to do with the reflected waves back by the backplate of k&n type pod filters. And that the ramairs are more effecient due to the all foam free flowing struture and nature of the material. Also that velocity stacks and socks gives you the best of both worlds.

still got S&B's on mine though as im a tightwad, and dont want to spend over a £100 on stacks and socks.lol 

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The velocity stacks are a tight fit on the the rs36's had to get some emery cloth on to them to get them to fit.

The do not seem to go all the way to the lip of the stack, so there is a gap between the two of a few mm. They are air tight so assume its not a problem.

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  • 1 year later...

Sorry to dig up this old(er) thread, but this way people don't have to repeat their earlier posts again.

Right.. So, inpired by this thread I went ahead and ordered some RamAir sock filters (MS-006) to replace my dual K&N's. In order to fit these foam filters onto my RS36's I first had to make a set of suitable bell mouths aka stacks.


To my surprise and wonder the foam filters I received felt completely dry, leading me to assume these were in fact NOT pre-olied. I searched the RamAir-website for definitive info on this, but only found they sell a cleaning kit containing filter oil.  So I concluded these foam filters apparently DO need to be oiled before use, and so I oiled my set with a generic foam filer oil and preceded to fit these onto the stacks on the carbs.

Compared to the K&N's the smoother response especially part- throttle was noticeable, and in that way I was very pleased. After a few 100 km's however the engine started to run increasingly rough misfiring occasionally. So I pulled the plugs (after first misdiagnosing the carbs) and found them covered in black soot.. Which explained the misfiring, but had me puzzeled about the obvious sudden rich mixture.

I tried contacting RamAir about my findings via the web page and email but have received no response yet. So instead I'll post my query here.

Are these filters supposed to be used dry, so NOT oiled? Or is the specific RamAir-oil in some way different that will not hurt the air flow as badly as regular filter oil? Non-oiled foam filters will probably work fine, but hardly filter any dust at all. Is that the trade-off that is connected to using this type of filter?

Hoping someone can shed some light onto this matter.

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