Valve Cap Problem on Longstroke A7

[1949BSA]

I ride a 1949 A7 Longstroke.
One of the Valve caps had a repair but is now cracked (and just before a rallye on the next weekend).
Has someone an idea what to do?
I´m afraid I have to look for a spare one?

Michael

[Swarfcut]

 Try the cap from the oil tank or the primary chaincase...both are the same thread. If one of these seals the rocker box, either application will be happy enough to run with your broken rocker valve cap as there is no real pressure to contain.

 Triumph twins use the same thread and with a raised hex, Triumph Valve Caps are a good alternative to the original part.

 Swarfy.

[1949BSA]

Swarfy,

thanks for the response.
The idea with a BSA primary cap works, I have one in my spares.
I have tested the original damaged rocker box cap on the bike today. I have cleaned the thread (it is still okay) and fitted it to the rocker box with a seal fluid. A test drive was positive  -  no oil leakage.

So I will start to the rallye tomorrow, with the extra primary cap in reserve in the tool box.

Michael

[1949BSA]

The Rallye Weekend  of the 25. Curbici Veterans 2025 is over!

Here is a short "report".

Unfortunately we had 2 days rain all the day (after 8 weeks very dry weather).
Several bike drivers quit the start.
I had already wet feet and hands before the rally star, because coming direct with the bike (ca 30 miles) in pouring rain. But the rain coat was fine!

The A7 starts well and I had no problems, not on Saturday and not on Sunday. But I lived on 2 days in wet socks, boots and gloves.
The main mark on the rally was this year the "Junkers Aeroplane Museum" in Dessau, with some airplanes and very interesting plane engines but also a stop for coffee and cake.

Also the Sunday starts again with rain. The night was much too short to dry the wet clothes and I managed to get back in my wet boots with still wet socks. The shorter rallye around 12 o`clock on 2nd day finished and even the rain stops for a while.

This year I got the 1. place on BSA A7 for Motorbikes from 1945 to 1960.
May be the rain helps me???

The seal of the broken cap works okay, but I will try to find a good original Longstroke rocker cover cap to replace the broken one.

Michael

[1949BSA]

Don´t no why the pic has turned.
When I click in the photo it turns in the "upright".

Michael

[BagONails]

Looking very fine there Michael, the damaged valve cap is barely noticeable!

I used to put plastic carrier bags over my socks when I was riding to apprentice training in the UK. My boots were old secondhand ones and leaked like sieves. What a luxury it was to arrive with warm and dry feet. Another one up the front of my jacket made a huge difference too.

[berger]

BoN present day your plastic bags would drop to pieces as you were riding but back int day i did same things .

[BagONails]

Bergs, too true, present day my shopping bags fall to pieces before I even get the shopping home... Nothing's proper any more!

[Swarfcut]

 Looks as if Michael's engine rebuild has been successful.  Back on the road and winning a Prize!  As we say "Looks the part". Well done.

 Swarfy.

[1949BSA]

Swarfy,

yes, I think my A7 rums well after the crank bearing repair last summer. The engine runs smooth with nearly non vibrations. But I still run the engine not hard; one up to around 50 to 60 MPH.
I´m very pleased with the bike.

BagONails,

I used plastic bags (from Supermarket) also in the late seventies, when visited a Vintage Bike Race at the Nürburgring.
I went down there from Hamburg in heavy raining the boots were soaked with water. But I had a pair of dry socks in the luggage and used these in combination with the plastic bags for the next 3 day until back at home.
It was a small taste of comfort in these days.

Michael

[Swarfcut]

 Just a further thought about these rocker caps. I had a look in the literature section for the 1949 Longstroke, sure enough the cap has a raised hex part 67 67, and almost the illustration of OI5 GAP on the top.

 Trev is correct in an earlier mention, the gap of .015 is correct for Longstroke engines  XA7 601 to ZA711192, according to Service Sheet 203.

 So a couple of conundrums...Longstroke rocker boxes come with these hex caps, often they are plain, not embossed, and also plain caps with a serrated edge, same as primary and oiltank caps. Original? Fit whatever you got?

 Secondly the Service Sheets indicates valve clearance is 0.003" on engines up to XA7 601, on inlet and exhaust. Seems a bit close to me. Roy Bacon says valve stem caps were fitted from'47-'50 so anyone able to shed light on this?

 Swarfy

[JulianS]

The change in valve clearance was due to the introduction of ramp cams from XA7 601.

Below from David Munros book "BSA Twin Motor Cycles" explains. He was from the BSA factory Technical Department.

[Tomcat]

Roy Bacon says valve stem caps were fitted from '47-'50 so anyone able to shed light on this?
Swarfy

Yes, my YA7 had caps on the exhaust valves, they were worn and at the time not available from the BSA parts suppliers. I ended up buying Ducati 8mm closing shims (caps) from a motorcycle shim business.

I found that the tappets were noisy at .015" and reduced them down to .012" and .010"  (it was a while ago so don't quote me on it!), the noise was gone and I had no further trouble.

[Swarfcut]

 Thanks Julian, that offers an insight to the change. TC...Good first hand experience there...Many thanks, another piece to the jigsaw.

 Swarfy.

[greybloke]

I have a similar issue, not so much cracked as missing. How does one cap go missing? I did see a nice set of 67-0067 for sale - but I just need one - and they didn't have the 015 moulding. Best course appears to be avail myself of the services of 4D models (London based). If you got the part or a CAD drawing they'll spin cast it in white metal (or gold, hmmmm...). It's either that or trawling auto jumbles, I guess.