I am new to the 4 stroke scene and am having some throttle issues. I have a Saito 45 which after the engine is advanced passed 1/2 throttle I get a huge rpm loss. It drops back to idle again once opened all the way. I understand that the fine mixture needle adjusts the low range or idle range, while the high mixture needle controls the overall rpm range or max rpm range. I have followed the procedures on setting both needles. First by setting the high needle valve by leaning the mixture to get an appropriate high rpm. Then proceeding to the low mixture needle valve to get the low idle set. But when I try to set the high needle I don’t get anywhere near max rpm. I am getting a higher rpm response at the peak of the 1/2 way point. I have checked the valve clearances and they fall within manufactures range. Compression seems much lower than my 2 strokes but being new to the 4 strokers I am not sure what the compression should be comparatively. Any help would be much appreciated.


Ryan