Out of tune?

[stu.andrews]

My A7 (1961) which I have recently acquired has an annoying fault which I hope someone can give me some advice on. I am running it in as the bottom end is completely new & have adjusted the mixture to be just slightly richer than normal. It was far too rich when I had it, with the mixture screw right in & black sooty plugs.Now, the plugs are light brown & the engine is much smoother. When idling, the tick over is smooth & starting is easy until....................a little "pop" or splutter & the engine instantly cuts out. Following this, starting is quite difficult. Although I have not had the time to check the ignition timing yet, I would say it is OK as, once running, the engine is smooth & pulls well.
Perhaps someone in your knowledgeable forum has some ideas to help me?

"Thanks" in anticipation!

[Topdad]

Hi Stu, if you are happy with the timing the next culprit I'd look at would be fuel. Check theneedle  jet block and the slow running jet ,the filter on the top of the carb also the bowl and float valve for debris/muck and the state of the tank and tap filter gauze also for muck and finally the hole in the petrol tank cap. if nothing found then start looking at points and pick ups etc . best of luck BobH

[iansoady]

Have a look at the cutout cable (and button) as it may be making intermittent contact to earth. It may be worth running it with the cutout detached from the mag end cover to eliminate this (although you may then have some difficulty stopping it!).

[Triton Thrasher]

Common causes include plug fouling by a too-rich idle mixture and fuel starvation by a sticky float or float needle. At speed, the vibrations keep the float working but it sticks at idle.

[stu.andrews]

Hi all. Have tried nearly all of the remedies mentioned (although not the cut out lead), fuel flow is good, mag pick ups & slip ring cleaned, in fact, nearly everything I can think of!! Will persevere & let you all know, in time, what the problem was.

Thanks all.

[beezermacc]

I seem to remember having a similar problem on a B31. I changed the carb completely and this cured it.

[stu.andrews]

Thanks beezermac. Will try everything else first, as it's only the tick over thats affected, before I go down that road but it's a possibility!

[Goldy]

Just one suggestion, an air leak between the carb and the head. all the best with it.

[stu.andrews]

Have stripped the carburettor & thoroughly cleaned it, trued up the inlet flange & obtained, by adjustment, a perfect colour on the plugs & smooth idling. Why the carb was so out of tune, I do not know. However, after a run of about 10 miles, the engine would not idle, cut out & was then difficult to start. Ah, the dreaded magneto condenser, I thought. By using a colourtune, where the spark can be seen, a spark was visible for a while when idling then the spark just stopped. So, it looks like the magneto is off to the rebuilders shortly. One question, though, has anyone found an easier way of setting up the timing, apart from the fag paper method, as it is not possible to use a timing disc as on Triumphs. I did think of just checking continuity across the points as the engine was turned, but apparently, this method is not very successful.
Any ideas would be welcomed.

Regards

Stu

(Sorry, should have put this in Ignition section)