Ok, so I didn't do much to the Shedouin! However, I think I may have the bike sorted. The bike has 2 CPU's. One for the fuel injection, and one for the ignition. The injection one is under the seat and easy to see and deal with. The ignition one is out of sight under the tank, and probably hasn't been disturbed for 32 years. A bit of unplugging and replugging has got it going again.

Oh .... 4x4 clutch not looked at!

No progress today as I've had other commitments, but the bike ran ok yesterday on the way to my friend and did about 30 miles. It also started on the button this morning.

So, the engine is in and running.

When I say running, I mean it starts and idles when warmed up, but it has a mechanical noise of some description.

How do I determine what is causing the noise? Can anyone tell me, what are the different noises and there causes please?

First try to locate where the noise is coming from. Rigt/left head or body.
Front if the body, rear of the body. Upper part lower part aso.

There are dozens of different noises good and bad an engine can make..

Is the ignition on time, way to early can make strange noises to.. To late and the engine wont rev..

Hi Geo

Timing appears ok at idle. Noises are happening without being under load. Appears noise is coming from the right hand side looking from the front of car. There is the occasional clacky noise at idle. If I rev a little and the close the throttle, there is a rhythmic clicking/clacking on the over run as revs decrease.

Further research on Google, suggests small ends.

How pitty it sounds, but This is very plausible..

Oh dear oh dear..

Engine noises ? ,
Sort of 4 different all dependant on engine running temperatures
Piston slap on cold start up , often disappears after a good run ,
A rumbling knocking noise that gets worse after running ( oil gets thinner ) could be big end bearings
A clicking sound that gets worse when engine is warm could be small ends , but never seen that on a 2CV,
Higher pitch rattle could be tappets , they normally quieten as the engine warms up
Try using a wooden dowel as a makeshift stethoscope , I bought a original doctors one at a jumble sale years back for £1

Thanks Roco, that's helpful

I'll see what I can hear!

Work in progress.