Rob:

Is your little ASP a plain bearing engine? If it is it may also be pre-ABC, and have an iron piston in a steel sleeve.

It is possible you have been running it with a castor blend, or straight castor oil. Going to a 100% synthetic can cause a dramatic loss of compression with an iron piston engine, and if yours has a plain bearing crank, the synthetic wont lubricate it properly, leading to rapid wear.

On the other hand, if it's a late engine with a ball bearing supported crankshaft and an ABC cylinder, check the glow plug as suggested by cde and the head mounting. If OK yu've probably sucked some trash in and ruined the cylinder/piston fit. Using a castor blend might bring it back.

Also, if the engine is new enough you could avail yourself of warranty service to have it repaired.

Bill.