OK, I give up !!!!!!!

[flywheel1935]

Seems harsh on engine builder, OP said it ran after rebuild then after a few weeks ran rough, now not running. As said by many, this is a fuel or ignition problem

Hi guys, Engine will be going back builder next month, he was made aware of my concerns and kindly called me directly to discuss further. we both agree that the engine
is making a 'strange noise' and I will be with him when we delve further into my problem.

[Roger]

You should be able to feel approx where TDc is against the compression when the plugs are in or your thumb over the hole with plugs out.  This will give you some confidence that the flywheel is marked correctly. I’m wondering if the timing is 180deg out. If you swap the middle two leads over and it starts and runs on two you’ll know it is.

Alan,

Having just rebuilt my engine I needed to set the ignition timing, rather than use the thumb over No. 1 plug hole I used a piece of 15mm. Copper pipe with a rubber glove taped over it. The glove is pulled over all the pipe except 1/2” at the lower end then taped tightly to seal it.The pipe then fits in the plug hole and when TDC reached on the compression stroke it inflates to show it is the correct position for timing the engine. If you cut off a finger ✂️(from the glove) and use that instead it is much more sensitive as it fills more quickly. I found this much easier than reaching round with a thumb.

 Roger

[bob46320]

To rule out fuel, squirt propane / butane up the spout - its what I have to do on my lawnmower at the start of season, after its first start, it runs OK for the rest of the season.
A tow start is often a good idea as it allows the valves to hammer up and down and make a better seal, also you will be getting a full 6/12 volts as the starter won't be grabbing all the power from the battery.
Another idea is to isolate the ignition circuit from the battery and use a battery charger to run the ignition.

[John Mason]

Hi, if you have new fresh petrol and a good spark are you sure your choke is fully operational. I recently had starting problems with my Ruby and traces the problem eventually to the choke not closing fully. All it required was an adjustment to the cable. If you think it is fuel problems just take the carb float bowl off throw away the petrol and fill with new fresh petrol then re fit. The reason I keep banging on about new fresh petrol is because it vaporises easier.

John Mason.

[Austin in the Shed]

If it doesn't start with a quick squirt of Easy Start into the intake there's something wrong with it.

[John Mason]

I agree with Austin above but I was not brave enough to include it in my piece for fear of rebuke for suggesting it as a lot of people don’t like it why I don’t know.

John Mason.

[flywheel1935]

OP update, Rebuilt engine now back in and running. It was a very strange issue, when the F/pump diaphragm leaked neat fuel into the sump and diluted the oil, the rings then ran in 'dry bores'. Still tight, but once primed runs first swing on handle, (on most occasions)

[Tony Press]

Wow ! How much petrol ? Did the oil level rise ?  How tight were the pistons ?

[Russlin]

Classic condenser symptoms. Otherwise coil.

Russlin.

[Tony Press]

Causing Petrol to fill the sump ?