Oil leak confusion

[Mick Boon]

I actually rode my new bike today for the first time, just around the yard, it goes really well and shifts through the gears nicely.  I left it ticking over for a while and noticed smoke coming from the engine, it looked like oil was coming from the head gasket on the left side.   I shut it down and the oil soon burnt off.    The funny thing is is that it seems to be fine now, no more smoke of leaking.   What can it be ?

[DAVE BRADY]

Hi Mick,

When you say it seems fine now does that mean that even when running there is no longer a leak?
Perhaps running the engine has helped the gasket to seal.
I notice that there are no washers under the head nuts.  Is it possible that the previous owner left them off and were they left off the bolts as well.  It may be OK but washers are specified for the head fasteners.  The other thing is that if the gasket has not long been fitted it may need the torque checking.  A fiddly job but worth doing.

Dave. 

[Mick Boon]

Hi Mick,

When you say it seems fine now does that mean that even when running there is no longer a leak?
Perhaps running the engine has helped the gasket to seal.
I notice that there are no washers under the head nuts.  Is it possible that the previous owner left them off and were they left off the bolts as well.  It may be OK but washers are specified for the head fasteners.  The other thing is that if the gasket has not long been fitted it may need the torque checking.  A fiddly job but worth doing.

Dave.

I just took it for a fast spin on the open road, when I got back it was leaking again but not as bad as before, there is oil on a head nut, I think it's the one you noticed has no washer.  I have no spanner that will fit that nut, do you know what size I need ?   

[Mick Boon]

A problem where i live is that it gets really cold at times, I have seen it as low as -43 C  this winter, it makes metal contract.The bike has not been running for several years.

[DAVE BRADY]

Hi,

It is 3/8 BSC / 3/8 BSF spanner.  There is no washer under either nut visible in the photo so it may be worth checking the other side.  Oil coming up the stud does indicate that the gasket is not sealing properly.
As the engine has not been run for a while it may be worth checking that the head is torqued down properly and take the opportunity to fit the correct washers.  The only way to this is to remove the rocker box and do all the bolts.  The workshop manual covers this and gives the sequence for tightening the head down.  It is probably worth getting some spanners and sockets.  Imperial and AF spanners are available as well as sockets but buy good ones and they will last for ever.

Dave.

[Mick Boon]

Thanks Dave, I will do as you suggest.

PS What des BSC and BSF stand for ?

[DAVE BRADY]

Hi

BSC is British Standard Cycle and BSF is British Standard Fine.  I think that you will find suppliers in the USA.   
It may be more convenient to get them from there rather than from the UK.
There is a  Canada BSAOC.  The contact is :- Barry Mitton 5 Appletree Court, Simcoe, Ontario, Canada N3Y 4V1    email :-  1963rocketgoldstar@gmail.com

I know Canada is a big place but there may be BSA owners not too far from where you live.

Dave.

[Mick Boon]

Hi

BSC is British Standard Cycle and BSF is British Standard Fine.  I think that you will find suppliers in the USA.   
It may be more convenient to get them from there rather than from the UK.
There is a  Canada BSAOC.  The contact is :- Barry Mitton 5 Appletree Court, Simcoe, Ontario, Canada N3Y 4V1    email :-  1963rocketgoldstar@gmail.com

I know Canada is a big place but there may be BSA owners not too far from where you live.

Dave.

Thanks Dave. I will drop Barry Mitton a line, he is practically a neighbour, he only lives 3 time zones away.

[Mick Boon]

Are these Witworth spanners what I need to work on my BSA ?


https://www.amazon.ca/8pc-Whitworth-Spanner-Silverline-SIL8/dp/B01M332ZQ1/ref=sr_1_1?crid=TWFSET3EZEFQ&dchild=1&keywords=whitworth+wrenches&qid=1615691892&sprefix=witworth%2Caps%2C258&sr=8-1

[chaz]

a good source of information closer to you   https://www.baxtercycle.com/  alternatively     https://www.classicbritishspares.com/collections/tools

[DAVE BRADY]

Hi,

Also E&V Engineering in Howard City just over the border in the US.  As they work professionally on BSAs it may be worth asking them to suggest a tool kit and a make and supplier for the spanners.   The nuts and bolts on a '69/'70 will have some BSF fasteners but will also have AF.  BSW and BSF spanners can be used on either although the sizing is different.  It is possible that someone will come on with a list that would help.


A bit of an aside is that even a relatively small country like the UK used to have different time zones based on sunrise.  It was not until the establishment of the railways and the need for a time table that the country really had the same time.  A reliable clock set to GMT put on the train would be used to set the clocks along the way.

Dave.

[Bess]

Hi,
    Dave correctly mentioned the need for washers under the head fixings.

To expand, BSA in 1970 identified an issue and further improved the head gasket seal by using thicker washers, part number 02-0861. If you cant source originals check what's available and that they are at least OD 0.750", ID of 0.380" and a thickness of 0.092".

Bes wishes...

[Mick Boon]

There's a lot of inormation here, but I'm still confused about the spanners I need to get.   Will Witworth spanners do the job ?

I will make sure to fit the correct washers Bess, but how thick washers under the head nuts can improve the head gasket seal is beyond me.

Thanks

[DAVE BRADY]

Hi

Whitworth/BSF spanners will fit some of the nuts and bolts but a set of AF spanners will probably be needed as well.

Dave.

[berniej]

It is a bit confusing! The CEI threaded components that we have on BSAs (mainly 26 TPI but also 20) need Whitworth size spanners. The spanner size relates to the shank diameter not the head.

BSF/UNF/UNC spanner sizes all relate to the measurements 'Across Flats' (AF) so use common spanners although they have varying thread profiles.

To make it more confusing, there are some sizes where one spanner size is near enough to fit both Whitworth and (e.g.) BSF.

This link may clarify! http://classicmechanic.blogspot.com/2011/06/mm-af-bsw-bsf-spanner-conversion-chart.html

My suggestion would definitely be to invest in a set of Whitworth spanners.

Finally.... You will find that you can't get a socket on to some of the head nuts and an open-ended spanner can't get the torque. In which case I suggest getting one of these: https://www.amazon.co.uk/gp/product/B00BH3QVA2 it's metric but adjusts to grip and does a good job!

Cheers,
Bernie