Symptoms of Vespa piston the wrong way up

[paulnobodyimportant]

Just re-built a Rally200 engine, but not for Rally200 that I have built in a previous thread. So this rally engine has a 12v upgrade, with new LML stator and flywheel and its gone into a GS160. Engine fires up easily and ticks over OK once the choke is pushed in, but will not rev out, splutters and has no power and appears to be running rich in the way of smoke and 4 stroking.

On the carb side and this is a new 24/24E Spaco carb, all jets are standard for this engine. Air mixture screw makes no difference and neither does jetting down the starter jet, or running with air filter off. I've also removed choke wire to make sure that the choke is fully in and fuel delivery is also OK. Suppose I could change carb, but last night, between 2 and 5am, I got to think about the piston and did I put it the right way up

On the electrics side, all stator resistances Ok and change of CDI unit, HT lead, cap and spark plug make no difference.

Now I'm sure that I put the piston the right way round, ie, arrow pointing to the exhaust port. But there again, I get distracted and things go on differently. So what are the symptoms of the piston the wrong way up, are they as I have described.

Thanks

[storkfoot]

When I got my Rally the piston was in the wrong way. I didn't realise and ran it like that for hundreds of miles. It was just generally under powered. A bit of 4 stroking but certainly not smokey.

[mick1]

have you strobed it ? could be too far retarded....

[paulnobodyimportant]

Thanks Paul. But first might strope timing as Mick hinted. Because I just set stator to normal mark. However, with a LML stator and flywheel it's probably best to check.