Quote:
Originally Posted by HookSet
Sidebar here, what did you adjust on the linkage to fix the backfire, mine does that when letting off the throttle a lot and it is driving my wife nuts.
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The first thing to consider when fixing the dreaded HD / Columbia backfire is what causes it. Backfire is caused a cart's ignition (spark) stopping before the flow of fuel into the cylinder stops. This loads up the cylinder with fuel and when spark starts again the big bang happens. Four things will normally fix a backfire:
1) There is a little round disc attached to the accelerator linkage under the driver's side floor. This disc controls when ignition starts / stops. It can be adjusted out so that ignition starts earlier / stays on longer with the push of the accelerator pedal so that any fuel entering the cylinder is burnt and not "stored".
2) The accelerator cable needs to be adjusted so that the fuel butterfly fully closes when the accelerator is not being depressed. A properly lubricated and adjusted cable is a must. Old and slow closing throttle cables will cause backfires. The throttle butterfly must snap closed with the pedal.
3) Proper timing. If your cart is electronic ignition then this isn't a giant concern but if it is running points it's a huge concern. If proper timing (spark) isn't delivered then the spark will miss the fuel on a rotation or two.
4) Better driving. 2 cycle motor should be driven a bit differently then 4 strokes. With cars, we are comfortable easing off the gas but still staying on it when a coming to a stop. Two cycle carts can be different. While coming to a stop, if you keep on the gas a bit there is a chance you will deactivate the spark (via the disc in point 1) but still allow fuel to enter the cylinder via the accelerator not being closed. To remedy, in your cart when coming to a stop immediately get off the gas completely and coast to your stop rather than easing off the accelerator into it.
The attached service supplement speaks to backfire prevention.