I have a Super Rocket with RGS tuned engine, with spitfire cam and 10:1 pistons.
The fuel available today is not in favor of too high compression.
You need octane 100 or octane booster for this.
I had to lower the compression on my RGS engine, to make it stop pinking. ( by installing a spacer under the cylinder !).
Take into account that the alloy cylinder heads we can find today (more than 50 years after end of production) has been shimmed several times in there life !
This rise the compression even more. !
A new high flow oil pump plus new oil pressure relief vale from SRM in Wales is a must today.
The new oil pump benefits with higher oil flow and stop wet sumping.
I use a manufacture new (from 1998) 389 monoblock 1 5/32” single carb. This setup works very well and has a crisp and quick throttle response.
It is not advisable to use twin carb setup. You can gain a little, but it is very fiddley and you end up with constant adjustment of the carbs.
Finding a good A10 head for twin carb installation, is not realistic today...
For valves and guides in the cylinder head, use modern vales with a higher degree of filling, and convert it to lead free in the same go. with oil seals on the inlet valves.
The cylinder headshop in Webley, arranged this for me I 1995, and this setup works sweet…
Dynamic balance of the crank is a must.
Pay attention to the cam followers, they ware out. SRM can deliver new units.
The SRM oil/ roller bearing conversion is a must on a A10 engine. The turns a good engine in to at strong and very robust engine.
Ignition:
Magneto is periodic nice, and look right. But it is endless fiddling and troublesome on a 50 year oil bike used only now and then.
Problem I have encounters with rebuild magnetos:
( Rebuild several times by a company in Sheffield and SRM, regardless of cost !)
Uneven ignition on the two cylinders, weak spark from start. Hard to start with the fuel quality available today. Need constant attention.
Last 5-6 years, and need to be rebuild again. 500 £ each time !!
Go for electronic ignition. It is accurate, bullet proof and give a much improved ignition.
Setting up correct ignition time on the magnetosystem is a night mare...
If the dynamo is old and worn: Go for a Alton AC generator unit with chain drive (belt drive give trouble).
This unit works very well and can give you H4 modern light.
Avoid 6V. Getting long lasting bulbs and equipment is a challenge.
All contactors burn out and last short time with 6 V.
I have BSA, Norton and Triumph. Some with 6 volt and some with 12 volt. All rebuild by me.
I regret my then stubborn attitude in the 90ties and keeping with 6V positive earth. !
If I was to rebuild again, it would be 12V with negative earth, using a Alton generator and electronic ignition or if possible AC crank mounted generator for my Triumph T110 or my Norton.
With belt drive and dry clutch.
Viking, Denmark.
BSA A10 GF, SR & RGS