BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: hoogerbooger on 08 November, 2017, 21:21:30

Title: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 08 November, 2017, 21:21:30
I have no air filter on my B40 star and on googling you don't seem to be able to get a copy of the original filter unit that goes inside the battery compartment/behind the air filter mounting plate.

The carb is an amal 627 and there's only about 15-20mm between it and the air filter mounting plate/hole into the battery compartment.

Anyone able to advise on my best options for an air filter ?

Title: Re: B40 Star air filter - what's the best option now
Post by: TTJOHN on 09 November, 2017, 10:11:31
You may be able to get a pancake air filter to fit but not sure.

Regards TTJohn
Title: Re: B40 Star air filter - what's the best option now
Post by: Bess on 09 November, 2017, 10:50:14
Hi hoogerbooger,

Try here:

http://www.bsaunitsingles.com/item.wws?sku=40-7829

Best wishes...
Title: Re: B40 Star air filter - what's the best option now
Post by: Dabbist on 09 November, 2017, 12:24:04
If you can't get a standard filter, some of the narrower pancake ones will usually fit, or you can get hold of a short length of steel or aluminium tube (you'll only need a few inches, dirt cheap on evilbay) which will fit into the end of the standard rubber tube link through the centre panel. You'll then be able to mount a small cone type filter on that, inside the "toolbox" so it will all look standard.
Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 09 November, 2017, 19:05:47
Thanks both for comments.

Bess, thanks for your link. Not sure how I missed that - as I went to the site. I actually have the gauze, the rubber  ring that that goes round it, the circlip....... but not the housing (that from the diagram I've seen) it fits within.    If anyone has a spare one or happens to see one at an auto jumble let me know !

Will have to take the suggestions and for the time being rig up something in the tool box area so that it looks right.

Kind Regards
Title: Re: B40 Star air filter - what's the best option now
Post by: Bess on 09 November, 2017, 20:19:43
Hi,
      One of these?

http://www.bsaunitsingles.com/item.wws?sku=40-7825U

Best wishes...
Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 10 November, 2017, 19:10:06
Bess

yes like that. I hadn't even realised it was integral with the air filter mounting plate (obviously come off on mine under previous owners). The one shown on the link seems to have gone. So will need to carry on looking.
Title: Re: B40 Star air filter - what's the best option now
Post by: Bess on 10 November, 2017, 20:26:50
Hi,
    If you haven't got a illustration:

Best wishes...


Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 14 February, 2018, 18:10:11
I'm struggling to find a solution.

To fit a cone filter inside the "tool box" the filter would need to be no more than 6cm long and 8cm diameter to avoid the battery, frame tube & battery holder. This seems small. Ont internet it usually doesn't have both dimension. If anyone knows a make of that size please let e know.

Similarly the frame, battery holder & battery, prevent a pancake filter being fitted inside the "toolbox" in it's conventional orientation. If I could find a suitable connection hose with a 90 degree bend and an offset pancake filter that is a maximum of 12cm diameter by 6cm depth, then I may be able to use the space inside the "tool box" cover. The ones I've found dimensions for are bigger in diameter. To fit them I'd have to remove or shorten the tab inside the tool box cover that I presume held the tool roll. I don't really want to do that, except as a last resort. In any case it would still need to be circa 6cm deep or less.  If anyone has fitted a pancake filter inside the tool box on a B40/C15 advice/photo appreciated.

Alternatively I could try bodging up a replacement filter housing as I have the gauze, rubber ring ( that it seems to go in) and the circlip. Bess provides the parts diagram on this thread. I found pictures of the outer perforated cover that appears to be 50/50 hole to metal. I can make that. But I can't see from the diagram how the gauze sits within the housing & how much much space is left either side of the gauze to allow the appropriate air flow. If anyone can provide some pictures or provide some indications to assist it would be much appreciated.

( A full detached  original air filter housing was on ebay before Christmas. it went for 12 ish & I bloomin missed it because I'm rubbish at that sort of thing and it locked me out when I tried to bid last moment .... V annoying didn't talk for a day or two.....which pleased some but annoyed my better half ! - I'm sure there's a 3D printing project here for someone who's clever like that)

Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 14 February, 2018, 19:21:23
Essentially, the front circular corrugated gauze filter is pop riveted to the rear concave perforated plate. The corrugations provide separation between the front and rear surfaces. On the filter I've got lying on my bench, there is an even finer sheet of plastic gauze sandwiched between the two metal screens. They have the rubber seal around the outside of the filter.

I assume you are missing the filter housing from the rear panel on the B40 which I believe from memory is simply brazed on to the panel.  Is that correct?
Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 15 February, 2018, 10:58:19
I have just been emailed by Draganfly Motorcyles to say they had a coupled of used cover plates with the attached air filter unit in stock. Have ordered one. Am very happy !

( so if anyone else needs one ? they know where to go)

Thank you to all for the advice. I wouldn't have known what I was looking for without it !
Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 15 February, 2018, 11:38:08
Is it a used B40 panel + filter rather than a C15 version?
Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 15 February, 2018, 17:09:49
Picture of air filter off my B40 (although it seems to be missing the perforated concave plate). Note that, unlike the arrangement for the C15 in which the filter is attached to the back panel, the filter for the B40 is separate. Instead it plugs into the metal adaptor which screws on to the end of the carb and then projects through the hole in the back panel.
Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 15 February, 2018, 21:50:33
Thanks for picture. Very helpful. Draganfly say it's from a B40, but I guess  I'll find out for sure when it arrives. Seems they had two but this was the last one.  fingers crossed.
Title: Re: B40 Star air filter - what's the best option now
Post by: JulianS on 16 February, 2018, 09:25:31
My 1961 B40 had a filter arrangement which was exactly the same as the C15 and just as the parts photo posted by Bess above, checking the part numbers they are also the same.

The 1965 parts book shows a slightly different assembly. Posted below.
Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 17 February, 2018, 09:08:43
The earlier B40's used the same carb size as the C15 and were able to use the same filter arrangement and connecting rubber hose. However, in 1962, they changed to a larger carb and at that point had to change how it connected to the filter - connection by rubber hose was no longer possible. Instead, they used a metal adaptor screwed on to the end of the carb which projected through the rear panel to the separate filter. My B40 is from 1965 and uses this arrangement. If the filter was still attached to the rear panel as per C15, it's difficult to see how the adaptor could be fitted. The parts book from 1965 is simply wrong and shows the much earlier rear panel and filter arrangement pertaining to 1960/1961.

I can't remember where my filter came from when I restored my B40. However, if you are careful, you can detach the filter from a C15/ early B40 rear panel and use that as a separate filter to plug into a suitable adaptor for you carb.

Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 17 February, 2018, 12:06:08
I was wrong about the change in carb size for the B40 - I was looking at incorrect data. They all used a larger carb than the C15. I was convinced that was the reason for the switch from the earlier C15-like use of rubber hose and attached filter to the later metal adaptor and separate filter.

One way of checking whether a B40 originally had an attached filter (which may have become attached) might be to measure the size of the hole in the back panel. If the filter was originally attached, the hole would have been 1 1/5" in diameter. If it was designed for the metal adaptor it would have had a diameter of at least 1 7/8".
Title: Re: B40 Star air filter - what's the best option now
Post by: Phil C on 17 February, 2018, 16:52:31
My 1965 B40 filter appears to be attached to the carb by a rubber hose which pokes through a hole into the side panel. The filter housing appears to be rammed in hard against the frame, which makes me wonder if the hose is a bit too long. I guess I'll find out soon when I try to get the filter out to clean it.   Phil (novice)
Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 19 February, 2018, 16:46:32
I have an air filter now (pic attached) .... but looks like it's not as originally fitted. I have a 1965 B40F and the aperture through to the tool box is indeed 1 7/8 inches. So looks like it never had an attached air filter originally & it was the separate type .

So need to consider if I can use what I have & how. The outlet from the air filter is 1 1/2 inches (38mm) The protruding part of the outlet tube extends only about 5mm from the tool box plate.  Not much to clamp against. The concentric carb inlet is 43mm threaded.  So how did the rubber connector work ? It must have gone over the carb inlet but did it did it go over or within the air filter outlet ? Was it jammed in or over or were clips used to hold in place ( none shown on parts diagrams)

If  the same arrangement was used on earlier B40's and C15's I'm presuming I have something that can be used and allow enough air flow .....If I work out how it should be fitted ?


(may be easier to detach  and use as a separate if I can borrow a dremel)
Title: Re: B40 Star air filter - what's the best option now
Post by: Phil C on 19 February, 2018, 18:53:29
Mine (1965 B40F) appears to be a hose (1 and 7/8 o/d) fixed to both the concentric carb and filter by jubilee clips. The filter I think is separate from the side panel but sits inside it. I'll soon be trying to get the filter off (next few weeks), which might be an issue as it seems to be rammed in pretty hard against the frame inside the side panel, making me wonder if the hose is too long.  But then I know pretty much nothing.    Phil (novice.)
Title: Re: B40 Star air filter - what's the best option now
Post by: AdrianS on 19 February, 2018, 18:54:06
Thats the same as my 1961 B40. I've got the monobloc carb.
I am missing the rubber seal that looks present on  you filter.
I still wonder how effective the filter is though as the pipe from the carb to the filter housing I don't feel is a very good fit.
Also a lot of British bikes had no air filters fitted. Often a chrome ring or trumpet with a wire gauze inside was fitted to the carb.
The problem with running no filter is that the bike probably will be running lean.
Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 20 February, 2018, 11:06:14
hoogerbooger. The ideal solution would be to acquire a suitable metal adaptor tube which pushes through the hole from the back of the rear panel and then screws on to the end of the carb. The filter would then be a push fit into the end of the adaptor. When I got my B40, I had to machine up a suitable adaptor for the filter.

The proper filter has a 10 mm flange on it relative to the 5 mm flange on the attached type of filter - however, the latter is still sufficient for the metal adaptor. As an alternative, I would be tempted to use a suitable length of rubber or plastic tube which can be held on to the end of the carb with a Jubilee clip and then glue or expoxy the filter into the other end. Of course, you would need to remove the filter from the rear panel you have which is held on by 3 thin welds if similar to mine. I would use a cutting disk on a Dremel to cut through the welds.

Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 20 February, 2018, 22:00:17
Blimey 3 blobs of braze can be tenacious. One hour with a small file and junior hack saw later  & I have the attached .....now with 10mm of outlet to attach to. ( no dremel available unfortunately)

AWJDThumper: Thank you for both suggestions which look sound. I will investigate both.

I presume it would also be sensible to see if I can fabricate an equivalent to the gauze cover ?  Looks like it was 50% metal 50% perforation. I'm guessing if I do that so that the air filter is as close as possible to the original set-up....... then I can probably use the the 'original main jet size of 140


Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 20 February, 2018, 22:47:55
I'll post a picture of the perforated end cap. I thought I had a spare but it turned out the one that was missing from my B40 filter!
Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 21 February, 2018, 05:13:06
On reflection, I think the perforated, concave end cover is completely unnecessary and is just an piece of over engineering by BSA. You need to ask yourself what the filter is designed to keep out of the engine with the main concern being abrasive dust. In that regard, the perforated plate plays absolutely no role in keeping out the dust (that's the job of the inner filter) and, at most, will filter out larger particles which the inner filter will do anyway. So unless you are restoring the B40 to factory spec (like I did), I would not worry about the perforated plate.
Title: Re: B40 Star air filter - what's the best option now
Post by: AdrianS on 21 February, 2018, 11:28:13
The filter hasn't been put in back to front has it? It looks like the perforated gauze may be resting against the filter housing plate!
Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 21 February, 2018, 16:45:48
no I just have the actual air filter wire gauze and not the perforated metal concave gauze cover ( photo attached from some American site of whatI don't have  & that's a copy) But  sounds like that can catch up later.

I've just checked on the standard air hose part 40-7835. Apparently it measures approx 44mm OD and 35mm ID. Whereas the concentric inlet is 43mm and air filter outlet is 39mm. Anyone know if this hose is likely to be flexible enough to go over 43mm. ( heat it up in boiling water first ?) 

( for info I measured wrong before,  in that the aperture in the tool box for the hose to go through is actually 2" (50mm))

( My 1965 B40F is not fully original spec with some B25 and other parts, but I'm trying to keep it looking in the right ball park - photo attached for other B40F owners interest)
Title: Re: B40 Star air filter - what's the best option now
Post by: AWJDThumper on 21 February, 2018, 17:24:02
The first picture shows the standard C15 inlet hose fitted over the outlet from my B40 filter - the hose stretches easily. The second picture shows my filter with the corrugated plate now fitted.
Title: Re: B40 Star air filter - what's the best option now
Post by: MelC on 01 March, 2018, 14:25:38
This is my setup as I could never source the correct air filter for a 1961 B40.
I will continue  the quest at autojumbles but don't hold out much hope.
Title: Re: B40 Star air filter - what's the best option now
Post by: MelC on 01 March, 2018, 14:56:23
Unfortunately the photo is too large, but the setup comprises of the standard rubber tube to the filter inlet.
then a conical air filter on the inside stub. As its hidden by the tool box cover it will do until the genuine article can be found.
Title: Re: B40 Star air filter - what's the best option now
Post by: hoogerbooger on 01 March, 2018, 18:35:11
perhaps set up an alert on ebay ?  there was a C15 panel and air filter ( with oil tank and battery holder) on ebay last week ish.

would be good to see the picture your air filter solution.  I used microsoft Paint to reduce the picture resolutions. google how to do it. Googling should pull up other ways.

good luck with the search
Title: Re: B40 Star air filter - what's the best option now
Post by: Dabbist on 07 May, 2018, 22:12:13
Hoogerbooger, I know this is a late response, but I have a centre panel with the air filter in place. Since I'll be fitting a different carb anyway I'd be happy to exchange my centre panel for one without the air filter.