Engine High Idle

Posted by RodneyCB750K1979 on
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Engine-High-Idle-tp4040909.html

I just completed rebuilding the motor and carburetors.  At cold idle, the engine idles at 1500 RPM.  After the engine warms up, it idles at 3,000 RPM.  I did the carb spray cleaner around the carb boots and retightened the band clamps. These are new rubber boots. No improvement. I verified the sync port screws were in position. While at hot idle, I can press down on the #3/#4 carb throttle tab and it returns to 1500 RPM. Once I increase the throttle, it returns back to 3000 RPM idle. My thought is as the motor heats up, the carbs positioning might change slightly causing the throttle plates to bind. I lubed the throttle cable. Has slack and needs replacing. The choke is in full open position. The Honda dealer suggested an intake valve could be not sealing completely when hot. I did sync the carbs.  I keep coming back to being able to get the idle down by pressing on the carb throttle lever.  Any thoughts?