Star twin air filtration

[stompy]

As my new (to me that is) 1949 Star twin runs no filters on its carbs,I worry about what it is ingesting. Does anyone have any ideas about filters for these? There is very little room behind the stacks,so they would have to be very compact! Any advice most welcome.

[bsa-bill]

depends where in the world you live Stompy

In the UK we use damp air filters (rain) seems to work seeing as some A's are still running on original bores

[stompy]

Thanks Bill, Im in Melbourne, Australia. Whats the story with the filters you mention?

[bsa-bill]

Ah sorry Stompy - I love Aussie humour but obviously my brand of funny passed you by
I was relating to the fact lots of our bikes have no filter (or BSA one which also counts as none) and it rains a lot so we don't get the dust issues you guys have to endure

[stompy]

You may picture me punching up crocodiles and tying them to the back of the bike,dragging them back to my hut and making saddlebags with their hide, but I live in a big city and pollution is more of a concern than dust. Maybe tire and brake dust!

[BSA_54A10]

Me thinkeths that K&N's will fit.
They will look a bit out of place but most intelligent people can deal with that.
Foam filters that are cut at a slant ( like Ducatti's ) will also work if you can find some in the right size ( Morrini 350 ? )

[muskrat]

G'day Stompy,
                   I have seen stumpy filters used on minimotos. I have a mate up here that has one on his Matchy, I'll investigate.
Cheers

[Brian]

Dont want to seem negative but I really do think you will struggle to find anything to fit a Star Twin.

For the benefit of others I've added a pic of the right side, the left is not much better. You can see there is only about a inch between the oil tank and carby.

Good luck.

[stompy]

Stuff all room its true,the left appears even worse.

[trevinoz]

My set of carbys only have bellmouths with gauze strainers fixed to them.
The gauze, as I see it, has two functions.
One, to prevent rocks entering the engine and two, to arrest flames on blow back which could save the bike from burning.

  Trev.

[stompy]

I like the sound of the gauze strainers Trev,as my bike shows evidence of a fire at some stage before my ownership. The left bellmouth is very close to the battery too. The float gets stuck sometimes and fuel pours out the top. Its quite a fire hazard and Im trying to make it safer!

[muskrat]

G'day Stompy,
                   the minimoto filter is about 1 3/4" long so may not fit. Trev's bellmouths with some light cotton fitted over might work.
been running the '51 for 25 years with no filter, only on 3rd set of rings.
Cheers

[stompy]

Trev,do you know a place that sells the bellmouths?

[trevinoz]

Stompy,
                  You could try Amal for the bellmouths.
The gauze in mine is brass. The theory is that a flame will not pass through gauze which was demonstrated to me at school so many years ago.
This is put to practical use in miner's safety lamps.

   Trev.

[*nick*]

Stompy, perhaps try investigating running a small foam air filter (dry type) from an Australian company called UniFilter, i've seen them on all manner of classic racing cars and bikes.