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?

I might add that Chief Aircraft told me I'm pretty well "stuck" with this engine. They do not exchange engines even if they dont make it off the test stand! Any ideas will be appreciated.

Send the engine to:

YS Service
1295 Industrial Court
Gardnerville, NV 89410

I called YS today. Someone in service had a few suggestions to try before I sent it back. He said from my description it sounded like the engine was "loading up". He suggested: 1 - clear out the fuel by closing the high needle and spinning to clear out fuel from combustion chamber. 2 - turn out high needle 2 turns not 2 1/2 as suggested in manual 3 - dont prime as suggested in starting procedure and if still does it, turn regulator adjustment screw in 1/8 of a turn and re-try above procedures.

This makes sense because after reading many YS post today I've noticed that sometimes the regulator adjustments are "out of wack" on new engines.

I will try these things when weather permits and go from there, thanks.

Good Luck!

Just an update. Tried the things YS suggested to me over the phone but no go. Still runs about 2 seconds then abruptly stops no matter what the regulator setting. If I had to guess I'd say its stuck open. Sent back to YS as Dave suggested. YS has it now I'm waiting to hear from them.

I'm sure they will get it out this week, not too much going on here in the frozen north.

sooooo what was wrong?

Happy ending. Sorry for the delay. Got engine back from YS about 2 weeks from when I mailed it. Invoice said "sticky plunger" or something like that. Regulator was stuck wide open I presume. Anyway the engine runs fine now. Cant wait to get a plane to put it on. I had to buy another engine for the plane I bought it for, cant have too many engines!

Glad we could help, please let us know how it works out.

Good Flying!