Recent Posts

1

A7 & A10 Engine / Re: BSA Goldflash Dynamo Sprocket

« Last post by limeyrob on Today at 11:43 »

At the peril of being shot down in flames.. I don't think the cork disc has any role in setting the cam shaft end float:
The cam shaft movement towards the T/S is set by the collar on the shaft running against the bush.  The cork disc would push this away.
The camshaft movement towards the D/S is set by the rear of the camshaft gear running on the face of the bush.  The bushes are flanged both sides and are a pair 67-0686.  The cam shaft end-float is set when the gear 67-0337 is pulled up against the shoulder on the cam shaft and no adjustment is possible.
The cam should spin freely with a few thou float when the gear is on, the cork and breather are superfluous to the end float.
The cork should be the thinnest to just keep the breather in contact with the case.

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A7 & A10 Engine / Re: BSA Goldflash Dynamo Sprocket

« Last post by Swarfcut on Today at 10:54 »

    A further note may explain.  Small cork washer....Idler shaft.   Big washer...Camshaft gear.

    The small one under the dynamo drive is preventing float on the idler shaft. The one in the cam gear is keeping the gear pressed against the face of the outer camshaft bush, locating the cam lobes under the appropriate follower. It is also acting to press the breather bush flange against the inner timing cover face, and ensure  alignment of the timed breather holes in the bush with the crankcase exit duct. When assembled correctly, there will be no endfloat on the breather bush or cam. Too thick a cork washer and the breather bush will bear heavily on the timing cover, and the cam will be stiff too turn. Choose a cork which fills the gap and is compressed lightly on assembly. Sanding down a thick one to suit is fine, and ensure the drive peg and it's depth of engagement in the bush are adequate.

 But Rob's right, there should not be much variation in parts, but may have been a way for BSA to recover inner covers machined a little too thinly at the breather bush location.*


 Swarfy.

 *Ford used this trick on engine main bearing housings, overboring the block/cap assembly to avoid scrapping a mis machined block. Main bearings were used with an oversize on the outer diameter, as well as being available as an undersize for reground cranks. Found that out the hard way....

3

Frame / Re: Petrol Tank woes

« Last post by Rex on Today at 09:54 »

To seal the cap hole make a bung out of thick rubber.

Or cut a valve + 4" circle out of an old inner tube and secure with a Jubilee clip. You can maintain a steady (and very low!) pressure then.

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A7 & A10 Engine / Re: SRM oil pump

« Last post by sean on Today at 02:53 »

make sure you have the pump primed and oil coming out of the return line before you fire it up

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A7 & A10 Engine / Re: BSA Goldflash Dynamo Sprocket

« Last post by Colsbeeza on 20.12. 2024 23:09 »

Peter, Limey, there is a lot on the forum about the idler cork. As Swarfy said, it is more about camshaft endfloat. I would suggest mainly about endfloat. I would read up a bit before you decide it isn't necessary. Mine needed a cork of 3.1mm thickness to take up the endfloat. I suspect if too thick, that may be the cause of cork breakup which some experience.

https://www.a7a10.net/forum/index.php?topic=16474.msg141024#msg141024
Col

6

Frame / Re: Petrol Tank woes

« Last post by sean on 20.12. 2024 21:52 »

John

I know I did not have enough evaporust but you say it would be very expensive to fill the whole tank with it.  My tank is not dreadful but I was worried about any rust at the bottom before I lined the tank with por

I do not plan to braize the tank but to line it.

John

If you plan on lining the tank follow instructions to a “T “ prep and temps are very important to a successful outcome.
Over the years I have had the best luck with Caswell 2 part tank liner over… did BMW 5 yrs ago still like new no sign of failure.

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Frame / Re: Petrol Tank woes

« Last post by jhg1958 on 20.12. 2024 21:44 »

John

I know I did not have enough evaporust but you say it would be very expensive to fill the whole tank with it.  My tank is not dreadful but I was worried about any rust at the bottom before I lined the tank with por 15.

I do not plan to braize the tank but to line it.

John

8

A7 & A10 Engine / Re: Sump plate studs

« Last post by groily on 20.12. 2024 21:29 »

The A10 however will produce a solid could of smoke that goes 2 or 3 gardens down and lasts for ages.  Considering how good a condition the engine is its beyond annoying.  It has an oil filter on the return and I'm now wondering if that empties into the engine too.

Blimey! That isn't good, don't blame you for wanting a cure then. Could be as Rex says above, but if, per your original post on this subject, we're talking 1/4 pint in a few days, or 5 fl oz, I'd be amazed if that would be enough to smoke out all the neighbours and take so long to clear. Maybe there is a return-side filter drainage problem . . . but what comes out the bottom will tell you what's dripped in, from wherever.
And there will always, I presume, be some oil in the bottom when it's been standing after a run, as the oil from the top end drains back down, plus some from the crank probably, and some from the timing chest maybe. 1/4 pint wouldn't be far off I don't think  . . .  If there wasn't some oil down there, there'd be no quick oil return on start up: there'd be the sort of delay we see after an oil change and full drain-off. (Some other bikes I have hereabouts are supposed to have about 8 fl oz in the sump . . .)
Good luck with further tests.

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A7 & A10 Engine / Re: Sump plate studs

« Last post by Rex on 20.12. 2024 21:07 »

The problem could be "both get run every week or two" as if they're fired up and run for a couple minutes, the oil never gets hot and thin, and so the ball valve never gets to seat properly again due to the viscous cold oil.

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Introductions, Stories, Meetings & Pictures / Re: Support the forum: Paypal Donation

« Last post by Caretaker on 20.12. 2024 20:58 »

This year's 're-donation' from the forum done, to a very worthy instance.