Is there an air leak in the inlet manifold?
Rob responded – Your problem sounds like an air leak in the inlet manifold. You have all the classic symptoms – poor/erratic idle, stalling, but runs when you use throttle (the accelator pump gives it extra fuel). Since you replaced the left head the most likely place is the joint between the head and the twin port manifold end-piece.
Why does my air inleakage distributor not idle?
The distributor is an 009 centrifugal advance. I replaced the left head because it blew out a spark plug. After replacing the head the engine would not idle, so I had the carburetor rebuilt. It runs better but still will not idle correctly – it idles okay, then it speeds up by itself for about 30 seconds.
Why is the idle speed not set at the specified RPM?
Inability to set the idle speed at the specified rpm indicates improper fuel/air mixture (too lean) or a fault in the ignition system — usually the former. Note: It doesn’t take much of a leak to affect the performance of the 34 series of carburetors.
What happens when air is sucked into the intake manifold?
Air being sucked into the intake manifold can cause – The car acts like it’s not getting enough fuel; i.e., running too lean. The car may run well at highway speeds, but the engine dies at idle and will only idle at higher than normal rpm (e.g., >1200 rpm).
Can a 125 horsepower engine have an air leak?
Since the 125 is constantly being operated at close to maximum output and peak rpms, the tolerance for an air-leak of any kind is “zero”. A high-revving 2-stroke engine with a significant air leak, is an engine that will soon produce a seized piston.
Can a small air leak cause idle speed to fall?
However in the case of vintage engines, only huge air leaks will result in rising and falling idle speeds. The majority of the smaller, yet equally destructive, air leaks will have no effect on idling. Another common practice of finding air leaks is the spraying of contact cleaner at potential leak areas while the engine is running.
Can a high revving engine have an air leak?
A high-revving 2-stroke engine with a significant air leak, is an engine that will soon produce a seized piston. High output engines that have significant air leaks will usually run fine so long as the rpms are kept low.
When to look for an airleak when your engine you?
Piston seizures related to air leaks are not just a result of an engine being run with an air-leak, but rather a result of the engine being run at close to maximum output with an air- leak. Where to Look for an Airleak When your engine seizes a piston…do not disassemble it.