The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: a101960 on 13.08. 2010 16:37
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I am minded to fit one of those pancake type air filters to my carburettor. Has anyone had experience of fitting one to an A10. My carb is a 398. I have noticed that there are two types. Central fitting and offset which one would be best fitted to the 389? Secondly has anyone any idea how much difference it would make to the jetting?
John
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I purchased an off set one from Surrey Cycles http://www.surreycycles.com/. It needs to be off set so that it can be juggled about to clear everything. I still have the standard jets without any problem with the mixture.
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Centre fitting fits cast head John, very little air resistance when clean anyway. Just had a look down the shed and think centre fixing would JUST fit an alloy head although you might have to put it on in bits,
I wont put mine on until I have the bike running right and then fit and see, Very easy to blow through but perhaps I don't blow as hard as an A10 sucks so maybe a drop on the needle needed and/or bigger cutaway, I'm no expert tuner though.
Ah Goldie got here first, good it goes with out alteration then
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You'll have to check the mixture afterwards.
A filter seems to have a bigger effect on mixture if you have wild cam durations and big valves.
I have a horrible suspicion that Amals tune better for throttle response with no filter.
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what I do is purchase the pancake (screw-on) air cleaner, remove the celluose (paper) air cleaner, and fit a K & N element.
The K & N is a much superior (cotton) media, and will last a life time. It is also less restrictive than the paper element.
Lyford classic Services are a good source for the standard pancake air cleaner.
This is an example of the air cleaner I use.
http://i302.photobucket.com/albums/nn82/orabanda/IMG_4510.jpg
Here is info on the unit; I have them on all my swinging arm A10's (and DT360, DT400 and XT500 yamahas).
http://www.knfilters.com/search/product.aspx?Prod=TB-0100
http://www.knfilters.com/filtercharger.htm
Richard
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just a note that monoblocks and concentrics have different sized openings.
So there are genuine concentric & monoblock pill boxes that screw directly onto the carb and there is the generic pill box that only comes with one size hole and slips onto a ring that you have to attatch to the carb.
If fitting the latter it is imperative that you either glue the ring onto the carb or lockwire the filter to the bike frame.
On my bikes I glue the ring on then glue the the end onto the mount then assemble the filter in situ.
You can fit the end plate either way ( stub in or stub out ) on any of the sets ( there are 3 different ones ) or the center mounts so they can get squeezed into some really tight places.
I use an oiled foam element in all my bikes and they offer no resistance to air flow till they are disgustingly dirty.
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Orabanda,
That is a sweet looking bike.
It doesn't happen to have a BTH magneto, by any chance?
cheers
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Olev,
Thanks mate,
It goes like a sailor into a brothel!
No, the BTH maggie is in the Super Rocket project I am completing (will be riding it down to Coolgardie in 5 weeks time!).
http://i302.photobucket.com/albums/nn82/orabanda/P1030046.jpg
http://i302.photobucket.com/albums/nn82/orabanda/P1030050.jpg
http://i302.photobucket.com/albums/nn82/orabanda/P1030037.jpg
Richard
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Thank you lads for all your advice and observations. I shall order a filter from Lyford they list one that screws on to the 389. And now a supplimentary question: Where can I get the K&N element from to replace the paper one.
John
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Follow Richards link, then goto - home - then customer support, gives this for UK --- uk.sales@knfilters.com