To rebuild myself or have professionally done

[Greybeard]

With reference to unneeded modifications: Changing the electromechanical voltage regulator to a DVR2 is well worth doing. It's a fit-and-forget improvement in my opinion. I put mine inside the original style metal case. I even used the original connection block.

[7iain7]

The plan is to keep the bike as close to original as financially and practically possible.

One thing I’m not sure about is having the engine components statically & dynamically, balanced?

[KiwiGF]

The plan is to keep the bike as close to original as financially and practically possible.

One thing I’m not sure about is having the engine components statically & dynamically, balanced?

This may help https://www.a7a10.net/forum/index.php?topic=6086.msg41598#msg41598

[Worty]

Bergs may be kicking his heels now he's rebuilt my motor

Seriously though, if you want to see what a hash a 'professional engine builder' can make of your motor, just look up 'Worty's A10 engine refurb', it'll make your eyes water.

[RogerSB]

Yes, if I were you I’d do as much as you can yourself, then you’ll know the ins and outs.

I’ve restored and rebuilt several Brit bikes and pre 1970 cars, but having no engineering equipment (or skills) I had to trust a local and well respected professional motor engineering firm for rebores, regrinds, etc. and then assembled myself.

I also agree with some of the others, keep it basically original but there are some sensible modifications worth considering - all discussed in detail on here.

In my opinion these are: External oil filter in oil return. DVR2 voltage regulator, LED bulbs (except headlight), inline fuses as appropriate and if needed SRM 4-spring clutch and cush drive nut. To make maintenance a little easier an SRM sump filter with its magnetic drain plug.

My own GF was already fitted with Eddie Dow fork dampeners, SRM belt drive for dynamo and converted to 12v (but keeping the original 6v dynamo) by p.o. and I’ve carried out the mods mentioned above and also indicators after fitting a sidecar.

Rog.

[Rex]

Really it must depend on how much or how hard you intend riding the bike when finished?
Sunday morning Summer-only bimbles don't really warrant LED bulbs, oil filters, toothed dynamo drives etc etc.
Similarly Thunder rods, SRM roller mains conversions must be a waste for 99% of owners.
That said, a new DVR2 reg would be far better than an a 60 year old electro-mechanical if the old reg was worn out and non-adjustable.
Get it back to how BSA intended and it'll still last longer than most of us..

[Worty]

Really it must depend on how much or how hard you intend riding the bike when finished?
Sunday morning Summer-only bimbles don't really warrant LED bulbs, oil filters, toothed dynamo drives etc etc.
Similarly Thunder rods, SRM roller mains conversions must be a waste for 99% of owners.
That said, a new DVR2 reg would be far better than an a 60 year old electro-mechanical if the old reg was worn out and non-adjustable.
Get it back to how BSA intended and it'll still last longer than most of us..

I would agree but, from my experience, the spin-on filter is a very good idea (I had a total of four fibre gears strip on mine in 10k miles leaving a lot of debris passing through the gauzes).  As I only have the plain bush, not roller conversion, and given the mess my motor ended up in, I think the oil filter gives some piece of mind.  As for riding, I get out on mine as much as I can when it's not being fixed.  Most trips are upwards of 150m, only stopping for fuel and a pee at the back of a hedge.  The bike gets very hot (not as hot as before though), and puts a lot of strain on components and oil.  I still have the primary/dynamo chain, stock 6v including bulbs, no inline fuses, and a non-SRM 4 spring clutch.  I do have a DVR2 and a Ebay sump with magnetic drain plug (mine wet sumps all it's oil in a couple of days so I have to drain and refill the oil tank regularly).

If your motor's very decent, I would simply add the spin-on to keep it that way if you're out a lot.  Most other things are fine as standard.

[Swarfcut]

 Simplest and most cost effective upgrade is a fuse in the battery earth lead. Brake light and horn are not usually wired via the ammeter, so a fuse in the earth lead  will protect them as well as the rest of the system. Small cost relative to replacing a fried loom.

    The type and amount of use the bike will get is also a consideration. Spending £££$$$$'s on crank balancing is fine if it will be raced, but for the odd Sunday pottering not really worth it. Same with replacing worn parts. Back in the day rebores and pistons were cheap...not so now. A good clean of the pistons and rings can transform a smoker into something reasonable, the same goes for old but expensive roller and ball bearings  which will continue to give good service. In other words, don't junk original parts as a matter of course without considering the cost/benefit of doing so. Experience shows some bikes become a money pit, with no chance of coming out the other side with billfold or wallet unscathed.

 I would add that complete dismantling, cleaning and inspection is simple and straightforward. Correct reassembly and remedial action on other folk's ill thought cock ups and neglect will produce a reasonable and reliable runner. It's the perfection and cosmetics that cost, these can be addressed if and when. Single most important aspect is to clean the crankshaft oilway between the big ends. "the sludge trap". No ifs or buts otherwise you will be on first name terms with you local crank grinder, who no doubt is perusing the ROLEX catalogue as we speak......

 Swarfy.

[Rex]

Simplest and most cost effective upgrade is a fuse in the battery earth lead.

I always do that too, but it's amazing how many posters (on other forums) insist that it's both electrically wrong and not how the manufacturers did it...etc etc.
Fuse in the earth lead means the maximum amount of potentially fryable cable is reduced to an absolute minimum.

[RogerSB]

Really it must depend on how much or how hard you intend riding the bike when finished?
Sunday morning Summer-only bimbles don't really warrant LED bulbs, oil filters,

'In my opinion sensible modifications to consider' - maybe I could have added 'depending on circumstances'. My own being an example. With a sidecar attached and indicators = lots and lots of amps a lot of the time (e.g. 2 stop lights, 2 indicator lights, indicator buzzer, that's without switching any lights on, then you double the lights for a sidecar. In this situation very low amp LEDs makes a lot of difference in keeping the battery charged. E.g. Two 5/21W incandescent tail stop lights = 0.83/3.5 Amps with 12v battery, double it for 6v battery. Two 1.25W/4W LED tail stop lights = 0.21/0.67 Amps. I also make a point of riding both my A10 and Velocette LE regularly, not only during summer months but in the winter also, admittedly not every day or in the rain as I did in the day, then long weekly weekend and daily commuter rides along with regular maintenance kept things working as they were designed to. So for me these days low amp LEDs are a necessity.

Also 'in my opinion' an external oil return filter is sensible and even more so if you only bimble around on a Sunday in the summer and an inline fuse is best from battery live to ammeter.

Rog.

[Greybeard]

I bought a double block and fused both sides of the battery, "To be sure, to be sure"

[bikerboy]

Fuse in the earth lead means the maximum amount of potentially fryable cable is reduced to an absolute minimum.
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I have changed from fuses to circuit breakers a lot easier than messing with fuses and you can get them with standard lucar slide on connections

[RogerSB]

Fuse in the earth lead means the maximum amount of potentially fryable cable is reduced to an absolute minimum.
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Don't forget in a vehicle where the battery positive is connected to the frame "ground/earth", "live" will be considered to be the negative terminal of the battery. On here we'll have both, +ve and -ve for their owners varying reasons. 
Rog.

[Rex]

Makes no odds if the bike is +ve or -ve earth regarding fusing the earthed terminal of the battery.

[RogerSB]

Makes no odds if the bike is +ve or -ve earth regarding fusing the earthed terminal of the battery.

Rex, I know a fuse can go anywhere, flow or return, positive or negative, supply or ground side, but it's good practice to put it in the supply side nearest the battery to protect as many components as possible, but yes, it will work anywhere in the circuit. It's basically terminology as to most people 'earth' usually means 'to ground' even when the negative side of the battery becomes the supply or live side.

In fact I have a fuse on both sides on my GF simply because the earth cable is longer and I can reach under the seat, pull it out to remove the fuse when working on or near electrical parts. In my case the supply or live side (being positive earth), is not easy without removing the seat first as there's lots of extra cabling, fuses and gizmos for my sidecar on that side.

Rog.