Hitchcocks Forum

Help needed as I on a long trip on my 500cc classic Elec Start bullet and the bike is fine at speed in fact runs beautfully. But it cuts out coming to a halt at traffic lights or pulling in to a petrol station, unless the revs are maintained. It then will not start until it cools down - but will start with a new plug (champion N3c). We set the needle to the mid-point as it had been mistakenly set to lean, and the of the centre plug is grey and the outside is black - so almost right. The air screw is at one turn out rather than the recommended one and a quarter turns. It pops on the overrun very slightly, suggesting slight leanness. It has a new coil and condenser. Points are fine. Bike has 6000kms on it. Any thoughts on what might be causing this 'shut down and inability start' once it is hot? I have ordered new plugs from our hosts but they will take a couple of days to arrive in our remote location.

Have you tried removing the spark plug when it won`t start to see if it`s wet with fuel or dry? How are the tappet clearances?

Also (Starts with a new plug)it could be a weak spark so what`s the battery voltage when it won`t start and when it`s cold.A good battery can recover voltage (amperage really)after being low.

Check tappets first. After that check battery is giving at least 12v under load. Sounds like it could be the condenser. Just 'cos it's new doesn't mean it's OK and a failing condenser often give up when it gets hot.

Thanks guys we are pretty sure it is ignition related after various checks. I have a new coil and condenser with us so we will replace them as a first attempt. Came back tonight and the bloody back tyre has a puncture and guess what, nobody fixes punctured tyres in Ullapool!

You NO answer questions.What checks? If you cannot repair a puncture you should not have a modern 1950`s bike.

Hi guys-------------- I use SLIME with great success.. Also, our hosts stock item No.98090, "Puncture repair kit with air"---------------(ARTHUR please note my balanced posting !!)

We fixed the puncture. Jaffa if you have nothing constructive or relevant to say about the technical problem then do not post comments on my forum questions. Good man.

You come on here for HELP then reply with a CONCLUSION and checks made.Also my advice was/were both constructive.Also you still no answer questions.Your conclusion good man is correct.

Not convinced about the ignition theory. I would have thought any ignition deficiency would manifest itself across the entire rev range, may be even more so under load. Sounds more like a weak mixture problem to me. Carb setting, air leak, blocked jet etc. Putting a new cold clean plug in may produce a stronger spark just enough to light the weak mix, fooling you into thinking the root cause is ignition related.