2001 Johnson 150, idle needle valve settings - The Hull Truth

emaier · 07-26-2007, 05:50 PM

My engine has not idled right since I bought it last year. Its rough and stumbles and coughs and sometimes it sounds like a cylinder is missing. I disassembled and cleaned the carbs and this seemed to help. The idle needle valve settings were between 4 to 6.5 revolutions out from being lightly seated. I was told, second hand, from a tech that the place to start before adjusting was 1.25 turns out. This was bad advice. I couldn't get it to started. I eventually opened them all to 5.25 turns out and the engine idles, but not as well as I think it should. What should be the starting setting for the needle valves?

Thanks for any help you can give.

A1 Outboard · 07-26-2007, 06:48 PM

With those fine threaded mixture needles, start with 5 1/2 - 6 turns out for a starting point.

Before setting the idle adjustments, first decarbon the motor with 1 or 2 cans of Engine Tuner to help clean off the pistons, recirculation valves, and free up any stuck rings if they are not too bad. Use an infrared temp gun to check for about 140°F on each cylinder head to make sure the thermostats are operational. Use the factory manual and set the sync and link to spec following the procedure exactly like it says. Then run the motor and set the carb needles while its in the water, not on a flusher.