16h cutting out when hot/after 1 -2 miles

It’s common for mags to behave like you describe when the capacitor is shot. Sadly I’m not a mag expert to know if you can test it other than by checking for a spark when it cuts out when hot! 

Dan 

If you are lucky it might be loss of valve clearances. If it restarts in 10mins, it might be as simple as that. Have you the correct clearances?

How does it stop ? Slowly fade away with the throttle open perhaps suggesting fuel and maybe a blocked cap breather ? ...Have you tried opening the fuel cap ? Does it pop and bang and backfire or is it just that it stalls easily at a junction and then won't re-start ?

How experienced are you with older single cylinder bikes ?  The first question to ask anyone who has not owned an Amal equipped bike before is whether you're operating the choke correctly...Sorry if it's a Grandmother and eggs question, but it pays to start with the easy things.

Has the bike always run well in the past ? What is the magneto history ?

Hi Steve,

   The old adage of trying the easiest things first is the best advice. I had the problem David describes so this might be worth checking. If you have a austenitic exhaust valve these need a lot more gap than magnetic steel does. Take a feeler gauge and a couple of spanners and when it cuts out check if there's a gap. If no, set it at 2 thou when hot and see if it cures the problem.

hello  Well running hot means the engine is labouring and this could be the primary chain is too tight, or even the rear chain as well  or the ignition is too far retarded  or advanced  or the fuel running weak, So check the lot and you find the culprit  have fun  yours  anna J       

... probably the mag. Although I always had trouble with my 16H vaporising petrol especially if I left it for 10 minutes or so after running.

My '56 Dominator had exactly the same problem. Started fine, ran for a short while, engine just stopped dead. No spluttering, no slowly fading, just stopped. Started easily again after 15 - 20 minutes.

No spark. Problem was in the magneto, broken wire which when hot, moved slightly so there was no connection. Dale Middlehurst solved this, and arranged for the mag to be rewound.

Problem was solved.

Richard

Try the cheap options first  and  whatever you do, don't take the engine apart. Neither you nor it will enjoy the experience and it won't help it to run!