Points ignition misfiring up hills

[shawit]

My standard series 2 which is running the original points + flywheel started 'misfiring' up long hills on the way to Weymouth last weekend. It wasn't really backfiring as such but it felt like it was 'misfiring'. This stopped around town and only happened on the return journey again up hills if I tried to go at any speed.

I'm assuming it's an ignition issue and not fuel related. What would be your guess?

[Warkton Tornado No.1]

Up hill riding will often mean that the engine is under the greatest load & bearing in mind the engine speed fan cooling, there are likely many candidates for the cause of misfiring.

Fuel is certainly something to suspect though your's may be fresh & a good quality high octane.

The increase in load with decrease in cooling may also allow any carbon build-up to glow hot & cause pre-ignition.

As for the points ignition itself, the plug, plug cap, HT lead, coil or the condenser may be breaking down. Any of those components don't always fail completely. However, unless you know it's good, I would suspect the flywheel magnetism.

[hullygully]

are you using double spring GP points on a 6-pole stator?

[lofty]

I had a similar thing a few years back, where once warmed up the engine would stutter under load or at higher speeds.
It turned out to be the coil in that case..

[shawit]

Thanks for your responses. There is now a list we are going to work through including a decoke - it doesn't always cut out in response to the ignition switch.
I haven't stripped anything yet, so I don't know what points are fitted.
I'll let you know what we find. Thanks again

[Adam_Winstone]

Missing going up hills is often an indication that your bike is about to go onto reserve as the fuel level reflects the gradient, meaning the tap and inner feed tube has less / no fuel above it.

A mate often runs into this on a club night as he rides to mine, which is at the bottom of a hill. We then go back up the hill and his bike misfires or cuts out halfway up. Same place every time (lol).