RCU Forums - Quadra 65 problems

I have a Quadra 65 in my Giant Aeromaster. When the engine was new it ran great with lots of power. For the last year, I have not been able to get it to run very good at all. The problem seems to be carberation. The symptions are; dificult to start, very rough running at high end, very poor running at low end & stalling. Adjusting the needles have little efect & it seems to run best (if you can call it that) when the high needle is almost closed. I bought a carberator rebuild kit last summer and replaced all the gaskits, springs, diaphram & screen. Still the same problems persist. Someone recently told me that this engine is a reed valve type and it could be sucking air from the base of the nylon case between the carb and engine (where the reed is located) I was recomended to remove it and check to see if it is warped. When I did so I placed a straight edge on it and held it up to the light. With some light showing through, I took 100 grit sandpaper taped it to a plate glass table and block sanded it till it was perfectly flat. The plastic reed seems fine. After puting it all back togeather, the engine still runs awful. I just can't get it adjusted with the high & low needle valves.
I have tried everything I can think of to no avail. Any sugestions (other than the usual get a Zenoah G-62) would be greatly appreciated.