Own a C-150G. Flown almost daily. Last winter had to pull #4 cyl. and have it re-worked. Engine would loose 100+ r.p.m. on climb-out at about 1500-2000 ft. a.g.l. This would only happen on the first flight of the day as the engine warmed up. Shop said the valves or guides? were coked. I change the oil and filter every 40hrs. Now I think #3 cyl. has the same problem, but not as bad yet. It is also more noticable right after an oil change, (strange). I guess this is a common problem on O200a"s. I don't know how to prevent this from happining. Does anyone?

Lycoming has a Service Instruction downloadable from its website at <http://www.lycoming.textron.com/support/publications/maintenancePublications/serviceInstructions/SI1425a.pdf> which describes suggested maintenance procedures to reduce the possibility of valve sticking. The document, SI 1425A, is four pages long and describes the "rope trick" in detail. This technique is applicable to TCM engines as well as Lycomings.

Bill; I am surprised that your mechanic did not recomend pulling that cylinder.you are looking at a valve about to be swallowed. In other word, the valve stem will break,and the valve head will fall into the cylinder,and beat thrue the piston causing metal to be ingested in you moving parts then engine teardown,and overhaul. Pull the jug.marvel mystry oil nor relapping will help.Send yor cylinder to an overhaul shop. good luck. P.S. I've been an A/P for fifty years.