Originally Posted by
RINKER
... but odd it's ok when cold but not hot. Does anyone know if the Lycoming has any valve operated decompression mechanism to lower compression for starting as seen on other piston engines. If so that could be the problem. All it takes with this system is wrong valve clearances and you get this result.
It's not uncommon to find this sort of problem worse with a hot engine, because the low rpm compression is higher with fresh oil on the bores, slightly less piston to cylinder clearance etc.
No there is no automatic decompression-type system on these engines. Reliability is key and adding a device to deliberately make the engine fail at a certain time (ie by lifting a valve etc) would only reduce reliability.