Motorcycle Repair: Running Rich, air filter element, air fuel mixture

Question
Hi Bill, I have a 1966 Honda Dream 305. Problem is the spark plugs get carbon-fouled after only about 3 miles of driving. The bike starts like a champ, it does require application of the choke until warm. I have had the carb apart twice for cleaning,and adjusted the floats to 26.5mm. The main jet size is 120 and the location of the clip attached to the jet needle is position 3 which should be fine for Northeast Ohio. I have installed a new air filter element and made sure that the connecting tube is not blocked, installed and correctly gaped new spark plugs, correctly gaped the points, set the timing with a light and the idle with a tach.  The exhaust system is not original but is the same one in place the last time the bike was used regularly many years ago. The points have not been changed nor has the tappet clearance been adjusted (the motor has not been apart since it was run everyday). What else can I do and in what order would you do them. Thanks for all your help. Tony

Answer
Tony, I either have to remove the flame arresting screen in the inlet or poke a small hole between the screen segments and shoot carb cleaner down the air bleed ports in the carb inlet.

They can get plugged-up pretty well and that shuts off the air source to the emulsion tube which holds the main jet and to the idle circuit. When that happens, you get unmixed fuel droplets sucked into the air stream instead of a air/fuel mixture.

Your idle jet should be a #35.

Dream condensers can start failing, but that will show up as deeply pitted point contact surfaces and irregular timing/running.

Make sure you have 12v to the coil and that the spark plug caps are not resistor types. Sometimes the spark plug leads can arc inside the frame causing misfiring and plug fouling, as well.

Checking the tappet clearance is always a good idea, along with a camchain tension adjustment.

Bill Silver