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Bike stalls when hot

2893 Views 1 Reply 2 Participants Last post by  Capt.
I have a '99 Honda CBR F4 - bike is carburated.

The bike runs great and is easy to start and maintain when ice cold. It stalls however after frequent stops at traffic lights.

The cooling system keeps it within normal operating temperatures...but when it gets to the higher side of "normal" it easily stalls.

Any idea??
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I would check first for vapor lock. It's caused when fuel reaches a boiling point and vaporizes. Check your fuel hose routing to insure that it doesn't lay against any of the metal components of the engine. Other things can also give you those symptoms like bad coils that, once warmed up, breakdown and loose voltage. A restriction in the idle jetting of the carbs due to gum buildup. The motor gets plenty fuel when cold because of the enrichening valve (choke), but once warmed up and no longer being supplmented with fuel, the engine will starve for fuel (lean mix) at idle and stall. Check the color of your plugs. They should be tan in color. You didn't mention that the engine miss fires or coughs, looses power in the upper rpm's or backfires. Based on that, I would consider the above first.
Hope some of this helps.
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