I've always wanted a YS engine after about 7 years of modeling with everything from OS .46's to a Saito 180. I purchsed a YS .63 from Chief Aircraft and Sunday put it on my test stand. I'm using Morgan Omega 25% with about 1 once per gallon castor oil added (SIG). I'm using a new OS F plug. I started it 2 and 1/2 turns out as per instructions. It started right up and I stopped and re-started it several times. IT ran good. I was impressed. I ran it very rich lots of smoke (almost an un-usual amount of smoke I had never seen anything like it). I also noticed that after running the engine was NEVER HOT. I mean you could grab hold of the the cylinder with your hand (I had never seen this before either).

I ran a full tank of fuel thru it (about 12 OZ) then filled the tank back up. About 10 mins later I went to re-start it and this is when the trouble began. The engine acted as though it was hydro-locked (I mean a mechanical lock!) yuck!

I thought the cylinder had filled with fuel (its mounted up-right however) so I took the plug out and turn it upside down and used electric started to clear it out. It seemed like lots of oil (not fuel) came out the exaust and cylinder . I then tryed restarting but it did the same thing again. It fires then immedeatly locks up. When I say locks up I mean a horrible mechanical like abrupt stopping) just like a hydrolock. I popped the rocker cover and the springs, rockers, and valves appear to be functioning properly. Now I cant start it. I'm afraid if I continue I'm going to screw it up worst till I figure out whats going on.

Does anyone have a suggestion on whats happening or should I just send it back. I see that YS engine dont have a crankcase drain like Saito engines. Does anyone know what happens to excess oil in the bottom of the crankcase? How does it get out?