ORIGINAL: Kweasel
I have used a supertigre carb, an OS7L and OS7D carb on my OS160. All the carbs with spraybars pulled fuel better than the 91-160FX carb. My testing method was quick and dirty, I simply raised and lowered the tank and measured the distance I got between too rich and too lean. The 7L was the best followed closely by the 7D, the Supertigre carb was good but restricted the engine by 200 rpm. I made the mounting universal by tapping the existing holes 10-32 and using set screws.
I considered the set screw method the first time around and if I had it to do over again I think that would be the way to go over drilling and tapping the neck of the carb. My first attempt got the carb mounted just fine and tight but since it was a back yard machine shop effort on my part the carb now sits just a bit accuse from 90 degrees to the crank. Looks a bit funny but shouldn’t cause any problems. I think now using some brass tubing as shims to pre drill the neck would have gotten the holes in the exact right spot but then again the setscrew method would have worked right from the start. I guess it all comes down to if you are satisfied with friction or mechanical attachment.
Scott