Twin Carb Airfilter (Commando too)

I saw this advertised recently http://www.britcycle.com/Products/K&N/060673C.htm
I'm considering it for a 650ss with Monoblocs
Any experience/comments?

Thats a K&N brand filter of which I am a big fan.
One of the first things I did after Amal overhaul was switch air filters to K&N. I have used the same brand on a variety of automobile engines as well.
They offered two types/sizes for motorcycle twin cylinder. The one pictured was the larger offering and I have since replaced it with a narrower profile (like the one you pictured) I found on the CNW site which makes it a lot easier to remove from a Norton engine with twin Amals. I did trim down the inlet collars just to make it even less of a hassle.
K&N builds a variety of high quality air filter offerings, the other photo is of a K&N I ran on a dual carb V8.

When I first purchased this it didn't fit so I went with the thinner manifolds and turned the filter upside down. It's a tight fit but will work , I don't see why it wouldn't fit unless those carbs stick out further.

When you consider that only one carb is ever sucking at a time, then those double filters offer a HUGE increase in filter area versus single pod filters.

So, IMHO, they should work very well.

My original Atlas air filter was effective for big leaves and small twigs only.

Servicing the filter was a scratch and scuff risk on the oil tank and battery box, so considering its ineffectiveness, I ditched it for velocity stacks. They give me a satisfying Norton "growel",

Had these been available at the time, they might grace my Atlas now.

IIRC, longer intake manifolds increase torque, so something may be lost if thinning the manifolds to make fit becomes necessary.

Slick
.

On Concentrics/Commando yes and liked it. Can’t say I’ve seen the Monobloc/Featherbed version.

texasSlick said:

My original Atlas air filter was effective for big leaves and small twigs only.

Servicing the filter was a scratch and scuff risk on the oil tank and battery box, so considering its ineffectiveness, I ditched it for velocity stacks.

Click to expand...

You mean this old design?

No rubber sealing along the periphery! Anyone found a replacement for this filter element? I'd like to keep the wedge-shaped housing.

A rubber seal can be made using pourable Polyurethane rubber. When crosslinked and set, I believe it's temperature resistant up to 93 degrees C (200 'F).
This should suffice. Would it bond to the paper element?

- Knut

mdt-son said:

You mean this old design?

Air Filter Element, Norton Dominator » Classic Bike Spares

Air filter element. For Norton Dominator, 88SS, 650SS, Atlas, G15. Made in England. OEM: 069650, 06-9650, NM25403/1 Our part no: 069650

www.classicbikespares.com.au

No rubber sealing along the periphery! Anyone found a replacement for this filter element? I'd like to keep the wedge-shaped housing.

A rubber seal can be made using pourable Polyurethane rubber. When crosslinked and set, I believe it's temperature resistant up to 93 degrees C (200 'F).
This should suffice. Would it bond to the paper element?

- Knut

Click to expand...

That does not resemble my original filter element as far as I remember. I remember mine to be very thin, and do not remember the composition of the filter media, it may have been a fine mesh screen.
I remember the frame was of wedge-shaped cross section. A very crude affair, but original equipment. My Atlas has several peculiar features which suggest it may have been a special build, so being original does not guarantee typical OEM.

Slick

Out of curosity, are the studs for the manifolds above and below, instead of side by side, like the later heads. If so, I THINK the carbs might be sitting closer together than the later heads. If so,I might have a K&N filter that fits the closer spacing. I bought it at a swapmeet many years ago as it was listed for a Norton twin carb.. When I tried to use it, it was for a narrower spacing than on my commando.

I am pretty sure these air filters are a K&N style, but not made by K&N. I was told that K&N wanted a guaranteed order for a larger run than anybody was willing to commit to. British Cycle Supply and CNW found another firm willing to make a smaller order. The filters are narrower than the "usual" K&N filters and will fit on bikes with the CNW electric start. Apparently will fit on an Atlas as well.

franko said:

Out of curosity, are the studs for the manifolds above and below, instead of side by side, like the later heads. If so, I THINK the carbs might be sitting closer together than the later heads. If so,I might have a K&N filter that fits the closer spacing. I bought it at a swapmeet many years ago as it was listed for a Norton twin carb.. When I tried to use it, it was for a narrower spacing than on my commando.

Click to expand...

I have a '64 650SS head with bolts either side of the ports - so I'm not sure how early you're talking.
Carb centres are at about 2.6"