Anyone seen one of these? (breather pinion)

[unclemeat]

Take a close look at the position of the peg and compare it with yours (if you've got one lying around).
Any ideas ?

[bsa-bill]

It is the camshaft pinion with the peg that engages the timed breather.
Now having just had a look at mine (engine rebuilt but still on the bench ) I notice that the peg on mine is in a slightly different position
as can be seen on the attached picture ( I hope)
I have heard that there was several version of the breather although only one is listed in my spares book and only one camshaft pinion also.
Interesting? perhaps its something that depends on year of manufacture?

All the best - Bill

[RichardL]

This is an interesting question and there are experts who could answer definitively, but it is amusing from an amateur's understanding to try to figure it out, so, I have a few ideas, in no particular order of most likely:

1. It is from a 1946-50 A7 that used a different breather path than later A7s and A10s (information courtesy of Roy Bacon, "BSA twins and Triples"). As I have a '55 A10, I don't know where the breather port in the timing cover occurs in the early A7s in relationship to the pin on the rotating breather.
2. It is from an A7 vs. an A10, which, having different strokes, may require different breather timing.
3. It might have been an experimental part that escaped the factory.
3. In Bill's photo, and on my partially diassembled engine, it is not clear as to whether the breather drive pin is relocated or if it is the puller holes that are relocated. The only rational I can think of for this would be a damaged casting form that was easier to modify than restore to original. (This is really remote.)

I would really be interested in knowing which, if any, of these theories is correct. The question made me consider the breather path in my A10 for the first time. On following the path I found the output on the drive side aiming down from below the cam bush housing. This then solved a small mystery regarding the oily mess on the outside of my drive side crankcase half. That mess seems to be one of the symptoms of the engine problem that brought on the current rebuild effort. 

[bsa-bill]

Hi Manosound Take your point re the position of the peg however I  think on mine the peg is not in line with the keyway ( difficult to be certain now that the nut and tab washer are on).

On a bit of a tangent, when I put the pinion on the camshaft I did wonder how camshaft endfloat is controlled, as far as I can tell it just a case of tighten up the nut until endfloat is correct ( I over tightened it and it locked up )
No mention of shims or any other way in the spares book or manual, the pinion is however a very tight fit on the camshaft.
Come on all you experts enquiring minds need to know

All the best - Bill

[RichardL]

Bill,

Per the various maunals, breather end play is controlled by using the correct thickness of cork seal on the face of the cam pinion. As far as I can tell, this also controls cam end float. Very quaint, with it all depending on a piece of cork.
I think this is correct, but if there is doubt, call or write one the well-known shops. They are ususally quite happy to provide information. 

Richard

[trevinoz]

I have one of these. It belongs to my 1950 Star Twin which is the early long stroke engine.
                                      Trev.

[flatdeck]

Hey Trev,
Is there a photo of your Star Twin available? I'd like to compare.
DaveInNZ :-)

[trevinoz]

Dave, the Star Twin is in a thousand pieces at the moment and is No. 3 on the restore list. The tank is going in to be stripped and repaired and rechromed shortly. Other bits are being done as I feel like it.
I am attempting to attach pictures of the two types of breather fitted to A7/A10 engines. The one with the stepped top is the early type, fitted until being shrouded by the timing cover, I believe. The other is the type used until the end of production.
   Trev.

[flatdeck]

LOL, I only dare take off one piece at a time 

[flatdeck]

BTW Trev. Does your Star Twin have a single or twin carbs? I'm unclear about the standard fitting on these, certainly twin carbs was an option.

[jfligg]

Hi David 
  Only the 49 Star Twin was fitted with twin carbs.  From 50 onwards they had a single carb.  My 49 has a single carb which was retro fitted for ease of tuning.  Did you get your mag back.  Jeff

[flatdeck]

Not yet. In fact, had an argument today with the chap I gave it to four weeks ago. He told me four weeks and NZD600 since it was likely that bearings, slip ring and condenser would need renewing. I accepted that. So I sent him an email last Friday and left a couple of phone messages earlier this week. Today he rang me to say that the cost estimate had gone up to NZD880 since the slip ring and bearings need replacing "he had been told" and it was not likely to be done until Xmas. I asked him who had told him that and where was it and he told me he had sent it away to be done. I was not happy since I went to him because he advertises as a magneto specialist and he said four weeks. He also told me originally he had a new machine for rewinding set up and would be using that but clearly that was b*ll*cks.  Anyway I got a name out of him and tracked the guy down who has the mag. I rang him and just asked him for information coz I no longer trust the chap I had gone to. Seems my best bet is for this guy to do the job since by the time I get it back and find someone else it will probably take even longer. I'm a bit annoyed that it took 4 weeks to find out nothing has happened and I had been misled. On a brighter note I did get a fibre drive gear from the UK for NZD40 including shipping and have sent that off with my AAU for reconditioning. I am hoping to get that back by the start of next week, which should have coincided with the mag rebuild but there ya go .... Glad you asked ??? 

[trevinoz]

JFLIGG, are you sure 1950 Star Twin was single carb? According to Amal list, 1950 used the same pair of carbs as 1949 but with different bowls. Mine has one 1950 type bowl and one 1949 type bowl.
1949 - 275AR/1A & 275AS/1A
1950 - 275BA/1F & 275BB/1F
The difference in the bowls is the 1F is longer than the 1A from the bottom of the bowl to the carby union. Probably to get the drips away from the magneto.
I don't know why mine has the mixed bowls but the carbs look like they are original.
The Star Twin had the single carb fitted from 1951 with the new short stroke engine.
                  Trev.

[RichardL]

Flatdeck,

I was surprised by the cost of the magnieto rebuild quoted by whoever it is that has your unit. If you are of the type to do most of the rebuilding of the mag except, maybe, rewinding the armature, you could have SRM Engineering rebuild the armature, leaving the rest of the assembly to you. Else, you could just send them the whole unit and have them do the whole thing. I strongly doubt that it would cost as much as NZD880 and you would be pretty much assured of a premium part when you got it back. Also, another source of parts to keep in mind is www.magneto.co.uk, they have a great selection of parts, however, it appears they are not currently offering armature rewinding. Now that I think about it, maybe the guy that has your mag is sending it to SRM and turning his profit as the middle man. It seems that enough time is being allowed for such a transaction. I'm not trying to stir up trouble, but I feel bad for your situation.

On a whole other topic, from my point of view, "bollocks" probabaly does not need asterisks, but "bullsh*t" probabaly does. Maybe Erling will comment on this language issue.

Regards,

Richard

[flatdeck]

Re the magneto rebuild. I rang the chap who now has it and asked him to tell me what was wrong with it. Apparently the shaft is bent, the slipring and bearings need renewing as well as the expected rewind and condenser. I asked him about the estimate and he said that he always over-estimates. That way he never upsets the client at the end. That's Ok with me since I'm not of the type to rebuild the magneto (unfortunately... see above post re taking things off one at a time  ) . I don't mind paying someone else to do the right job and I don't think he is sending it to SRM or anywhere else for that matter (it's already been passed to him from the original chap after all). I just want it back before Xmas. Here's hoping!