That info is a great help, thanks very much. The valves are presumably not original (I'm guessing the originals may have had BSA markings ?), but have very little wear so I think can be re-used but I'll get an expert opinion on that.

I don't have any engine history - the bike was directly exported from the factory to Eastern Europe where it spent 85 years of its life. Was geared lower than sidecar so I suspect it has down some fairly gruelling service. I am determined to get it back to good order and a gentle retirement puttering around here in N.Z.

I'm doing a precautionary total strip down - however the bike was running really well, despite very worn guides, a broken valve spring, badly worn exhaust rocker pad, worn cams, and two fractured rocker box mounts. Rather surprisingly, the main and big end bearings seem as new. Minimal play in the rocker spindles, which were very, very well greased - the exhaust rollers seem new; the lnlet rocker spindle has been bushed.

All good fun
Thanks again for your helpful advice.
Cheers,
Bevan

Thanks for the feedback. That summary is useful thanks, but I was most interested in the valve to guide clearances.
My valves and seats seem in good order, but there is quite lot of play in the guides. An engineer I consulted was suggesting using an insert of some sort but that made me nervous. I think he was hoping to avoid driving out the guides since the head is quite vulnerable to cracking I guess. However, in an exposed valve low lubrication situation, I have been told that cast-iron guides are still the best.

Hi folks, I've found a lot of postings on this forum about valves & guides, but can't find anything on clearances, so - what would be a safe valve guide clearance if using cast iron guides ?
Thansk,
Bevan

Thanks Dean,
I may have a lead on someone who has several rocker boxes, but if that fails,s, I'll look to getting mine repaired.

Have the head, barrel and piston off today. The inner exhaust valve spring is broken, there is a lot of play in both valve guides. Amazing that despite this, the bike started 1st or 2nd kick, idled, and ran really well ! Doubt that a modern bike would be so forgiving.

Piston and barrel seem pretty good and there is no detectable play in the small or big ends,so that is a plus.

Cheers,
Bevan

Hi folks,
Both of the rear mounting lugs on my 500cc S29 rocker box are fractured - see link to video clip. Does anyone know where I might be able to find a replacement, or is it likely to be possible to braize these back on ?
https://youtu.be/rlL7D6uydas?si=I5xcb5Tmfx3MLQ_M

Cheers,
 Bevan

Many thanks for that info.
This 500cc bike is for sale here in N.Z. It has just been re-listed at a reduced starting price after failing to attract a bid at the equivalent of 14500 gbp. 
The oldest bike I have is a 1929 Sloper, so it certainly would be interesting to have this bike.

Apparently restored and running as of 3 years ago, but it is unclear whether it has ever been road registered here, or if there is documentation to facilitate this, which is a barrier for me anyway..

I'd want to be able to legally chuff it around a few local roads every so often. I find bikes in museums interesting of course, but also a bit sad - they were all built to ride.
Cheers,
Bevan

Hi folks,
Does anyone with knowledge of veteran BSAs have any view on whether the bike in the attached photo looks to be a genuine 1912 machine ?
Cheets, Bevan

An obvious point I guess, but make sure that the DVR2 you have ordered matches whether you decide to have positive or negative earth. All my older bikes are positive earth.
Cheers, Bevan

Thanks for the info folks.
Cheers,
Bevan

Hi folks,
Does anyone on this forum have any info or suggestions regarding this issue:

I am a New Zealand citizen who is intending to come over this summer and was hoping to be able to ride a borrowed bike to a nearby rally (I am a member of the BSA, Ariel, & Panther owners clubs and have several U.K. contacts who would be prepared to lend me a bike).
The problen is: it seems impossible for a non-U.K. resident to get insurance to ride a motorbike owned by someone else. As my late father was born in High Wycombe I have had, and presumably still could get, a British passport but this is not sufficient - you seem to need to be a resident. I have friends in the U.K. so could in theory claim to be resident with them, but I'm not wanting to lie, especially  for insurance purposes.
Is there anyone who can offer some advice on this ?
Cheers,
Bevan

In case it is of interest to anyone, here is the result of my Sloper rear sprocket being re-ringed (original was OK, but was 46 teeth).
Cheers,
Bevan

Hi folks,
Because I've had a beer or two, I thought I'd share my first experience of taking my Sloper to get a WOF in a small village in N.Z.

Me to the Tester: "the bike has an indicator and brake light exemption, so you can't test that; also, due to its age, the Czech tyres do not need to have the DOT standard marknigs required by the regulations".
Tester: "oh, o.k., Really ? I guess "ll take your word for that"
Tester: "Lets check the lights; can you put it on high beam please ?"
Me: "It is so old it is not required to have high and low beam"
Tester: "Jesus"; what the f**** am I supposed to test ?
Me: "Well, here's the headlight - its a 6 Volt system."
Tester: "You're not planning on riding anywhere at night are you ?"
Me: "no way; not with that crap light"
Tester: "Thank God for that".
Tester: "can I check the wheel bearings ?"
Me: "sure...it only has a rear stand, so I'll try to lift the front wheel up so you can spin it.
Tester: "I'll jack it up"
Me: "No you wont, the crankcase is lower than the frame rails'.
Tester: "what about the rear wheel, can i check that ?"
Me: "go for your life"
Tester: "o.k. seems fine"
Me: "So I'll need to show you how the gears work"
Tester: "Why ?"
Me: "well, I assume you will want to take it for a ride to test the brakes".
Tester: "shit no; I've never ridden a hand gear change bike and i'm not starting now". You rode here o.k., so I'm assuming the brakes work ?
Me: yeah, all good.
Tester: " Right oh; come on in and we'll do the paperwork"


Bevan
.

That will be machined slots in the valve head - my Ariel has those too. Here's a picture of my barrel.

And my previous comment about spark plug position was bollocks - don't know what I was thinking ! Heres a picture of the head with some bluing on it when I was checking for flatness.

An interesting difference in spark plug position compred to my 600 sv Ariel - my plug is directly above the piston.

You are lucky the gasket did not blow out - my Ariel has blown two gaskets over the years. I lapped the head  flat on a surface plate to try to prevent a repeat. Both the heads and the barrels do distort due to the heat.I may yet need to get the barrel face machined flat. A fellow Ariel VB owner has had his head & barrel machined and lapped together and is running without a gasket.

If you haven't already put the head back on, i'd suggest checking it for flatness on a surface plate or sheet of glass.

Initially, I had to tighten up the screw on my advance retard lever a lot to prevent it shifting as i ride - but it was my fault as i had sprayed CRC on the mechanism to inhibit corrosion, making it too free to turn. Took it apart, cleaned it and reassembled and its now ok.

As with your BSA, after a ride, the carb on my Ariel is far too hot to touch. Lack of clearance over the magdyno and from the carb mouth to the oil tank means that it would be impossible to add anything more than a very thin a tufnel spacer, but it never seems to cause any issue. Side valves do run really hot.

I hope your bike runs better once you getthe head back on. I must say, your initial descriptions made it sound like fuel starvation (e.g. blocked breather hole in the petrol cap; clogged fuel tap/filter etc..)

Cheers,
Bevan. 

Hi Mike,
Here's a photo of the dissembled tell-tale from my S29 Sloper.
Cheers,
Bevan