Security and Fuel (additives)

Many use E5 fuel, no need for lead additive as all Norton twin valve seats since they came into being have been suitable for unleaded fuel. 

I think Esso supreme is still ethanol free in Dorset, as for security I use a padlock and chain, but i generally dont leave it unattended for long!
Dan 

This machine when built had a Lucas PRS8 ignition light switch. They used a small Lucas spade key down the centre of the light switch knob. If the wrong key is used and/or a screw driver then the ignition can be operated but the RETENTION piece inside the knob gets 'mullered' and even replacing it and using the right key does not make it any more secure.
Options-use large chain. Fit a further 'hidden' ignition switch, either a toggle switch or real key switch. BUT break the ignition circuit, as just breaking the battery cct might allow the emergency start alternator function to still work. For any more ideas get in touch direct.
You should have a steering lock?

Steering locks and ignition locks are both often not heavily relied upon and insurance companies don't value their function highly either. Often, a good twist on the steering bar can break a steering lock and an ignition lock is easily pulled out with a slide hammer-like device, after which you can start it with a screwdriver (that one happened to me once, luckily someone saw it happening). So it's not a big loss that you don't have them, as they're pretty useless anyway for determined thieves.

Those disc locks are nice and compact, but on our bikes they indeed can't be used. I've tried clamping one around a spoke, but realised it would only take a cable tie to fixate it to go between the fork legs. Or one snap would remove the spoke, with the bike still being rideable.

So a chain with padlock or one of those armed locks will inevitably be what you'll end up with. Inform with your insurance company how many locks are needed. They often need two and one of them then has to be used to fixate the bike to something unmovable, like a fence. It all depends on the insurance company and the demands they dictate.

It is a pain though, having to carry those locks with you. A chain is in my opinion the best bet, as it can often be stored where your tools are to.

Regarding the petrol: I haven't had any problems with E5 in my Model 50, though I do remove the fuel in winter and replace it for a small amount of alkylate petrol (like Aspen) . Just to prevent the ethanol from collecting water and corroding the tank. And also to prevent the petrol from going bad (2 months are all that's needed) in the carb and leave a mess. I've heard ethanol also nibbles away at the zinc of the carb alloy, but haven't found any evidence for that personally. When in a bind, I've been using E10 too, though I'd rather not leave that for too long, with the zinc tale in mind. I'd really like to know if there's any (not theoretical) truth to that one.

If you ride once every two months, a fuel additive would be advisable to prevent it from going stale. If there are additives that actually do that. For winter storage, I don't know how good those additives are in keeping water out. In short, I've got no experience with additives. ;)

By the way, welcome to the club. You'll find they're quite a friendly and knowledgeable bunch. And do enjoy your 99 Dommie.

On dommies thay have a hole drilled in the bottom yoke that will allow the use of a small padlock. I use a  plastic covered heavy wire lock through the forks and front wheel  while at shows or in meets at the cafe , /club branch meetings. I also do not leave the bike anywhere where i cant keep an eye on it. Classic parts are too easy to sell. I also cover the tank cap vent with a little tape /magnet when not in use as it stops continuous venting and water vapour ingress. Wait till tank has settled/cooled off though as otherwise can build up pressure.It does work ,as you will find out if you ride off with it blocked !!.Lock can be fixed to carrier when not in use.And is usefull to secure helmet too.

Has been good for me and my mate; we both carry a chain like a belt. We park in opposite directions along side each other then pass the chains through wheel and swing arm on both machines. Even better if you can get a post or fence rail between you. 
J
 

I like the tape over the tank vent idea Robert! I'm definitely going to do that now (and indeed forget it and stutter to a halt the first time). For those with a flip cap, as I have on a Montesa that hibernates in the living room, a piece of cling film between tank and cap will do the same.

Can't believe I do that, but have never thought about a piece of tape for the twist cap on my Norton...

Often wondered what the best solution is to storing fuel tanks.

I read somewhere to just drain the tank completely and leave the fuel cap off and the tank will air properly and stay moisture free.

So that's what I do and it seems to work and give me a dry tank, but I'm lucky to also have a dry garage to store my bike.