OS 61FX Rich Mid Range Problem
06-03-2017, 09:50 AM
#1
OS 61FX Rich Mid Range Problem
guys, I have always had an "Overly Rich" mid range problem on my OS61FX.. note that I have had this problem with 3 different mufflers,,, so I am now just wondering if I am opening the Main Needle a bit too much after finding the peak RPM,,
my setup,,
stock OS 61FX, 20% Magnum Fuel, OS #8 Plug, Tuned Muffler, APC 11X8,,, 13,700 RPM with this Tuned Muffler,,
as for the Muffler I had a friend weld up a 90 degree adaptor and I put a .50 size Century Tuned Heli Muffler on it (see Photo), it flows better than the stock muffler and much better than the Pitts, so it works well but it is now richer in the Mid Range than ever before, and it Loads up with Fuel at idling.
another thing,,
my engine has a Remote Main Needle with the stock Carb, I have notice that the size if the Tubing between the Carb and Needle makes a big difference in tuning the Main Needle,, smaller Tubing ID makes it harder to find the Peak RPM, meaning that when finding the Peak RPM it is a very-very-very Narrow Point on the Main Needle,,, <so with that I had a Small ID Tubing on it, and I went back to the Mid size Tubing and it ran better, I am now going to try a Large size ID tubing if I have some..
after that I am going to try the Hotter OS #7 Plug to see if it will burn more fuel at Idle and in the Mid Range.
I am just asking for some feed back, maybe some one will think of something I have not
thanks guys
Jim
my setup,,
stock OS 61FX, 20% Magnum Fuel, OS #8 Plug, Tuned Muffler, APC 11X8,,, 13,700 RPM with this Tuned Muffler,,
as for the Muffler I had a friend weld up a 90 degree adaptor and I put a .50 size Century Tuned Heli Muffler on it (see Photo), it flows better than the stock muffler and much better than the Pitts, so it works well but it is now richer in the Mid Range than ever before, and it Loads up with Fuel at idling.
another thing,,
my engine has a Remote Main Needle with the stock Carb, I have notice that the size if the Tubing between the Carb and Needle makes a big difference in tuning the Main Needle,, smaller Tubing ID makes it harder to find the Peak RPM, meaning that when finding the Peak RPM it is a very-very-very Narrow Point on the Main Needle,,, <so with that I had a Small ID Tubing on it, and I went back to the Mid size Tubing and it ran better, I am now going to try a Large size ID tubing if I have some..
after that I am going to try the Hotter OS #7 Plug to see if it will burn more fuel at Idle and in the Mid Range.
I am just asking for some feed back, maybe some one will think of something I have not
thanks guys
Jim
Last edited by the Wasp; 06-03-2017 at 09:55 AM.
