Thank you for your reply Petec,

This posting is part 2 of my nightmare with this engine.

Part 1 started at the beginning of this year when I took out my Dash45 with this YS45FR invert mounted with Hatori tune pipe. The ship had been sitting in the storage for over 15 years. Before storing, the ship was only flown for less than 1 hour (engine not broken in).

All the time since the beginning of this year, I had been religiously following the instruction sheet of YS, opening the HS 3 turns, only turned a few clicks at a time back and forth when adjusting. This is when the trouble starts. Engine either quits from low idle to mid range, or cannot transit from mid range to high end. Have tried turning the regulator screw until it opens only 1/8 turns, but still did not work. During these 8-9 months, I have been tearing down the regulator and carb at least 7-8 times to the bolt and nut level, but found nothing abnormal, Disappointed, I decided to send the engine to YS Parts and Service, hoping to get the answer as to why the engine quits.

After I got the engine back in October, Richard told me he replaced the 2 bearings which are rusty, the diaphragm and gaskets. But I know the rusty bearings are not the culprit. For the diaphragm, no chipping, no damage. And I made the gasket using gasket paper before sending the engine to Richard, and engine could also start. 

Here come the interesting part :- when I got the engine back, I also opened the HS needle 3 turns. Engine starts but keep on quitting during transition from mid range to high end. I phoned Richard. Among a few questions he asked me, he asked how many turns of HS needle, I told him 3. He of course said it is way too rich. So I immediately reduced to 1.5 turns and engine transition to high end has no problem.

BUT the third/fourth time when I started the engine after this, it won't start. And I never had  intention to return to 3 turns of HS needle. Instead , I post this thread and asked for help. Just before I typed this reply, I removed the HS needle, as you suggested and cranked the engine using starter, fuel did spill out, meaning no blockage. In fact, I did mention in my first posting that when I removed the throttle barrel, exposing the 2 small holes at the bottom of the cylindrical hole, fuel did squirt out when engine is cranked. That means no fuel blockage up to the HS needle. I then suddenly switched to the idea of TRYING 3 TURNS OF HS NEEDLE AGAIN, and engine started right away. I experiment with 1.5 turns again, it would not start.

IN summary, it is very confusing with the setting of the HS needle. Petec, with your vast experience on YS, can you shed some light on the HS needle setting ?

Thank you.