I never seen a carb set-up like that. I supose the fuel/air mix gets to rotary valve through some kind of passage you cut in adapter. I would apply about 1 pound or less of air pressure to pressure fitting on exhaust. Make sure exhaust outlet is plugged so you can pressure crankcase. Now take some bubble water and spray and check for any leaks around front of engine. You will have to hold your finger over carb intake. If you find leaks where they should not be...it will not tune right. Hope this Helps. capt,n