Vespa won't start when hot?

Question

I have a 1978 Vespa P200E that will start fine when cold but after I ride it somewhere and try to restart it about 20 -30 minutes later it will not start. When I remove the spark plug it is fouled. Any ideas?

Answer 1

Has the top end ever been rebuilt (cylinder, piston & rings)?

If no, it's time to rebuild it.

2 stroke engines require rebuilds quite often.

When the engine heats up - the cylinder expands, lowering the compression.