Sport Pilot Talk

Can someone please tell me why this 503 will not run off choke??? Surely I'm not the only one that has had this problem.

Tango Bravo 1 wrote:Can someone please tell me why this 503 will not run off choke??? Surely I'm not the only one that has had this problem.

Not many here with 503 experience.

If your 503 has a Bing carb, it really doesn't have a choke, in the conventional sense. It has an enriching starting carburetor, which only works if the throttle is fully closed. If you're running throttle up with choke on, the engine will stumble. Use the choke only for starting, keep the throttle against the idle stop until the engine warms up, and then close the choke before you open the throttle, and your engine should purr.

And if it doesn't do as Paul advises? It is often an issue with the tiny jets within the carb being clogged or constricted by even tinier debris.

chicagorandy wrote:And if it doesn't do as Paul advises? It is often an issue with the tiny jets within the carb being clogged or constricted by even tinier debris.

True, but I always try the simplest fixes first!

When our older dirt bikes (carbs) did that, we always checked for air leaks between the carb/manifold/cylinder/head gasket first. Not knowing what a 503 is, if it's a 2 stroker, check the head gasket carefully. They have a tendency to burn out on 2 strokes, but are dead simple to replace. Oftentimes, it was just a loose bolt (bad vibrations) somewhere in the connection.

HAPPYDAN wrote:if it's a 2 stroker,

It is.