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Frame / Re: Petrol tank refurbishment
« Last post by Slymo on 24.02. 2020 01:33 »
I sorted most of the dents in my tank without cutting the bottom out, not that I don't agree it can be the only way sometimes, because whilst my tank was dented it was otherwise sound. I used the dolly on a stick in the attached picture and beat the tank on the outside with a length of quite soft 3x1" pine timber. This helped me lift the majorty of dents out to my complete satisfaction. The tank still has a few signs of age on it but noting that isn't in keeping with a 62 year old machine.
Frame / Re: Petrol tank refurbishment
« Last post by sean on 24.02. 2020 01:15 »
have you tried to see if another plater can salvage it ?
Frame / Re: Petrol tank refurbishment
« Last post by trevinoz on 23.02. 2020 21:23 »
This is tank number two.
First is the tank after stripping and before repairs.
I don't have any of the tank before it went to the plater but I was assured that it was excellent.
The copper pictures are what came back. A total write-off.
Needless to say that the plater closed up shop after he sent the tank back.
Good riddance.
Wanted & For Sale / Re: Wanted A10 gear lever
« Last post by RoadRunner on 23.02. 2020 20:52 »
I still have 3 gear shift levers in vary states/lengths - all from a box of A10 spares I purchased years ago.
The longer ones are approx 6" - the bent, shorter one is approx 4.75".

If of interest just pm me.
Frame / Re: Mounting problems with rear fender for BSA A7, 1951
« Last post by muskrat on 23.02. 2020 20:12 »
G'day Martin.
I agree with Swarfy in that the guard is not correct for a 51 A7/10, neither is the one in the link.
The one in this link is for a single but is the same except for the ears at the front (the twins don't have this).
A7 & A10 Engine / Re: Engine misses and loses power
« Last post by berger on 23.02. 2020 19:31 »
jim an exhaust is ok to use as an inlet, but not an inlet in an exhaust, I have got super rocket exhaust valves that have been sorted to use in the opened up shooting star head on the berger project
A7 & A10 Engine / Re: Engine misses and loses power
« Last post by chaterlea25 on 23.02. 2020 19:23 »
Hi Jim
I forgot about your iron guides, I still would not use abrasive though
Heres on from ebay £8

A7 & A10 Engine / Re: Timed breather, what is the actual timing?
« Last post by chaterlea25 on 23.02. 2020 19:19 »
Hi Swarfy,
Same coin different sides? LOL
Without the gear the cam can move a long way towards the drive side

A spring would kind of work but would allow oil from the inner gear case out through the inner centre  hole of the top hat, the cork washer effectively blocks that side so the case pressure has to make its way to the outer chamber and back in through the outer end of the top hat
Later Gold Stars have a similar system where the top hat is in the outer cover and spring loaded against the magneto gear, its location at the top of the timing case is furthest away from the oily bits probably helps separate the air from the oil
I know that any looseness in the "A" top hat causes oil to leak out the breather
I aim to get the top hat tight enough to make radial movement  (to and fro against the driving peg) difficult with finger pressure but easy with pliers
New cork washers seem to settle over some time and may need replacement or packing out with gasket material


Frame / Re: Mounting problems with rear fender for BSA A7, 1951
« Last post by BSA_54A10 on 23.02. 2020 19:09 »
There were a lot of BSA's that had a very similar rear guard.
What we need to see is the actual profile of both the guard and the tail piece edge on.
I could almost guarantee that they will not be the same shape.
The guard should have a lip pressed into it for the tailpiece to sit on.
It is not uncommon to find a one piece guard cut short and then drilled so the tailpiece can be bolted on to it or a hinged guard fitted after the hinge is cut off.

We treat them as if they are made of gold but in the day they were transport for the masses so whatever went into the space so dad to get to work or the family could go on holidays was what went into the space.
A7 & A10 Engine / Re: Timed breather, what is the actual timing?
« Last post by BSA_54A10 on 23.02. 2020 19:02 »
The problem with the time breather is it has a fixed timing.
Air has mass so there is a latency between when the piston starts to move and the crankcase vapour are sufficiently pressurized to start them looking for an exit.
The timed breather is only correct over a specific range of engine revolutions which funny enough are just above idle where crankcase leaks and blow by will be most obvious.
From then on it gets progressively out of sync with the pressure pulses .
It is exactly the same as engine porting in two- stroke engines and why variable port timing ,  (which everyone seems to understand just fine) produced such a massive expansion of the power bands.
Secondly the breather is another exhaust, and apart from the need to remove heat everything that applies to engine exhausts applies to engine breathing and this is where BSA made their big mistake in not taking the effort to work out the correct length for the vent tube .
If the vent tube ends at a pressure pulse node then it will *** out oil .
If it ends at an anti-node it will be bone dry .

Bad breather timing is a big contributing factor to ring flutter at high revs ( normal Musky riding speeds ) which is a big contributing factor to blowing all of the oil out the exhaust pipes when traveling for long periods with the throttle WFO.
The latter was the prime cause of A 65's throwing rods in the USA where there are lots of flat out riding roads and a to a lesser extent in Australia.
Because UK roads are narrow , slow & full of bends & corners these problems did not become apparent to BSA ( or any other motorcycle maker ) till it was way too late.
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