I am going to change my "K+N" filter (looks like a massive DCOE filter) for an airbox with a remote cone filter.
So few questions
1. engine is ST170 on ITB's. making about 185bhp. So what size ducting/filter
2. Any particular type of ducting. Will need to be about6-700mm long. I know smooth lined is best, but a rigid tube won't work, it needs a flexi to allow movement between engine and the filter (which will be fixed in front/to one side of the radiator)
3. Suggestions for the filter?

Cheers
Clive

I used 4" wire wound flexy duct with an air box & trumpets on the Delorto 45's with a cone that was embossed K&N.

I'm not saying it is K&N as it came from China and cost £8

The engine produces 180 bhp.


Paul G


Description

I think K&N do a catalog with BHP ratings of there filters. From what I recall all the other manufacturers don't seem to actually measure the filters ability to filter - seems a bit of an omission. They seem to stock some generic and list by bhp (which is proportional to air flow, so seems sensible).

Filtration performance of "cheap" alternatives may not be all that good, some appear to be no more than a stainless woven sheet, no better than a tea strainer. Not much help against abrasive dust.

Dan

Thanks for the replies chaps.
I will buy a proper branded filter, I need to keep the hose to 90mm max, but it seems the pipercross airboxes use a "mere" 3inch inlet. So 80mm should be enough.

quote:

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Originally posted by cliftyhanger
Thanks for the replies chaps.
I will buy a proper branded filter, I need to keep the hose to 90mm max, but it seems the pipercross airboxes use a "mere" 3inch inlet. So 80mm should be enough.

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I sized the hose and filter on the throttle body diameter, so 70mm hose. 240bhp and hits the rev limiter (7200rpm) in
third easily

Description

[Edited on 19-2-19 by 40inches]