QuestionHi Howard,
With engine idle hunting from 1100 rpm to 1600 rpm restricting the carburetor inlets had the same results for both carburetors. Starting at the carburetor inlet, opposite what the Haynes manual calls the air rectifier hole,I slowly started closing the opining. Not until 1/4" remand open did the rpm fall to around 900 rpm. At 1/8" from full closed it dropped to around 860 rpm and at 1/16" 600 rpm to stalling. When I only closed off the rectifier hole but not the carburetor intake, the rpm fell from 1100-1600 rpm to 600 rpm. I had a tach/dwell meter connected and never seen a rpm increase or smoothes, just hunting.
I adjusted the carburetors by lifting the piston of each carburetor about 1/16" and adjusting that carburetor for a increase in rpm and then a drop off. If I hold the piston at 1/16" the engine rpm will drop to around 600 rpm and the engine will remain running. Pushing the piston lifting pin full up causes a rpm increase then a drop to about 600 rpm and the engine also remains running.
I place the uni-syn against the carburetor intake with the engine idle around 1200 rpm with no indicator movement. I tried it with the disk full open to full closed and all in between. Placing the uni-syn against the carburetor intake blocks the air rectifier hole and drops the rpm as I mentioned before. There is a small hole in the uni-syn's opining circumference that I tried to match with the rectifier hole still no indicator movement. I also tried holding the uni-syn about 1/16" from the intake so as not to cover the rectifier hole. This works in keeping the rpm up but still no indicator movement.
Thanks Al
AnswerSomething is wrong with your gauge since you know air is entering the carbs.
You need to set the throttle stop screws backed out more to get the idle down. After you get the idle down below 900 RPM, then balance the two throttles with the hose method since the gauge you have is not working.
Only after you have the idle below 900 RPM should you try to balance the throttles and then check the jet settings by lifting the pin ALL the way up. Keep in mind when you lift the pin on the front carb you are testing the REAR carb not the front one.
When you have the RPM below 900 RPM and lift the front pin all the way up the engine should drop off and sound like an old John Deer tractor. If the engine speeds up and stays fast the REAR carb it too rich. If when you lift the pin the engine dies the rear carb is either too lean or you didn't balance the throttles good enough.
Only move the mixture nut three flats and rev the engine to clear it and check again.
When it is finished and correct you will be at 700 to 900 RPM and when you lift either pin ALL the way up the engine will drop off and sound like an old tractor or just running on two cylinders. Rev the engine between each test so as to clear the engine.
Howard
