During extended testing on one of our prototype Bailey 4V-200 engines we have discovered that the lead residue from AVGAS can coat the exhaust valve stems sufficiently to cause the valves to partially seize in their guides.

We have been using AVGAS for economy tasks in competitions for several years in BAILEY 150/175 engines with no problems, however we would now recommend that AVGAS is not used exclusively in any Bailey Aviation 4 stroke engine.