I have a Saito 72 that runs sloppy-rich at mid-range and lean at full throttle and idle. I bought this engine second hand and I could not get it running right. I called Horizon and described the problems to them and in the conversation they informed me it had the wrong needle valve, spray bar and idle needle. I got those parts from them and installed them. Now I have the rich mid-range problem. When I called Horizon again the tech I got this time just wanted me to send it to them and also kept telling me to try 30% fuel. Well that is BS. I understand that the motor might have more performance with 30 % but that is not the problem here. I am running 15% Power Master in all my engines and all my other Saitos run fine with it. This 72 has a new rear bearing, the timing has been checked twice and the valves are set right, it has a new OS f plug and turns a APC 13x6 over 10,000 RPM. So I don't think it is "wore out". There are some things going on here that I don't understand such as the gap between the needles is around .040 at full throttle. Yet even at this much gap it still goes lean and dies before the barrel even gets down to the idle position, and is still rich in the mid-range. The high-end needle is open 2 1/4 turns. Another thing I have noticed is that the end of the spray bar is some-what smaller than the opposing end of the idle needle and as the carb closes and the barrel moves inward the end of the spray bar goes into the end of the idle needle and stops all fuel flow. I put a fuel line on the nipple, when I blow in the line as the barrel closes, before it gets to the idle position the needles overlap and the flow stops.
Can anyone suggest anything?
Thanks for any help
4 4 4 4 stroken ron