Engine Troubleshoot

Background
I still having problem with my OS 50 Hyper engine for my Century Raven TR3707. It probably need proper engine tuning, or engine brake-in, or new parts, or total new engine will more cost effective for me.

I had the crank case ( now I know the correct term for what I previously call "engine block") replaced since mine was broken in my last crash about one month ago. I have reused back all the internals.

I am using 15% Nitro, so that should work fine with a normal engine.

I continue with the test flight and trouble shooting.

Wednesday 2009-01-28
I took a quick flight session to see if I can figure out the problem. Brought it to PHAF field II, started the engine. Take off and have hover, then let it running in idle.. Looks very good.

From Remote Control Helicopter - 2009

However I was not able to continue the testing because it started to rain.

Saturday 2009-01-31
Brought the Raven to PHAF field II again. It was at about 9.50am.

This time, the weather is good. I was alone, I need to be extra careful. I already had half of tank of fuel left from the previous test flight.

I started the engine, put into hover, engine runs ok.

From Remote Control Helicopter - 2009

Landed, put on idle, check engine temprature, it was quite hot, turn the High Speed Needle (HSN) richer 2 clicks.

From Remote Control Helicopter - 2009

Then continue to do the hovering.

Just when the fuel about to finish, suddenly the engine died! Let it rest for about 15 minutes, while thinking very hard what I need to do.
Tried start the engine again, but starter not able to rotate the crank shaft. Using my hand I need to put lots of force to rotate it. I opened up the glow plug, flush the fuel inside. Now the the starter is able rotate it. Put the glow plug back and I able to start the engine. Soon just when I about to take-off, the engine died again!!

This time same symptoms, so I quickly open up glow plug, and tried to flush the fuel from the engine, however this time even with glow plug is out, the engine still very heavy and the starter not able to rotate it.

At the end of the session, I was wondering if I really should get a new fresh engine!!

From Remote Control Helicopter - 2009

Finding So Far
Current symptoms:
1. The engine is very easy to start
2. It runs ok (at low RPM), I able to hover my remote control chopper
3. After about half of the tank (or a bit more) the engine suddenly stopped
4. Very hard to rotate the crank shaft, seems like something is holding the piston or shaft
5. It let it cool for about 15 minutes it will able to start again.
6. This time it can run just for few minutes only.
7. Verified that not due to hydro-lock since, even when I open up the glow plug, the crank shaft still very hard to rotate.
8. Verified tuning won't able to resolve the issue.