1955 NH350 engine running problem.

[will_curry]

A poorly magneto usually gives starting problems but runs better as
the revs go up. Surely a rich mixture will burn rich no matter how good
or bad the spark that fires it is?

I've used a neon 'flasher' spark plug cap in circumstances like this.
If it's still flashing as the engine dies when you open the throttle it's
probably not the spark.

I agree with Roger about magnetos - a weak magneto can make life
very difficult.

[Mick D]

Hi

Your symptoms point towards a fuelling issue so I would carry out a scrupulous carb clean, checking all internal galleries are clear, but you say the carb has been cleaned. If you're sure there's no debris in the carb, have a look at the auto advance mechanism if you have one, a sticky unit can give similar symptoms. If your bike has a manual AR check it's still functioning.

Regards Mick

[jj.palmer]

At last have found the problem, on stripping the carb. again, on this occasion, I found that the main jet had become unscrewed thereby negating petrol being drawn upwards into the engine unless the choke was fully closed to give it that extra suction.
My own fault for not tightening the jet sufficiently, a simple mistake leading to a lot of frustration.

John P.