Hi, Nirmala1865 your instrument gauges and lights can alert you to most electrical and engine issues they can not warn you about failed engine gaskets or seals so your engine has to resort to old fashion alert methods of colored "SMOKE SIGNALS" here is a breakdown of their meaning:
1. COLORLESS OR SLIGHTLY BLUE SMOKE on start-up means your air/fuel mixture is at the right composition and everything is well burnt in your combustion chamber.
2. BLUE SMOKE on startup is usually caused by failed valve seals dripping oil into the combustion chamber when the engine is not running.
3. YELLOW OR BROWNISH SMOKE at start-up means your air/fuel mixture is too lean. Too lean means that there is low fuel but high air mixture in your combustion chamber.
4. WHITE SMOKE on startup may be caused by a blown head gasket allowing coolant to enter the combustion chamber and may start dripping out of the exhaust pipes or mufflers. Smoke while riding is usually caused by worn out or damaged valves, seals, guides, pistons, rings, or cylinder walls.
5. BLACK SMOKE on startup is usually caused by too much fuel in the combustion chamber this can be due to air/fuel mixture adjustment too rich, accelerator pump improperly adjusted, faulty choke or not in the off position, air filter dirty and clogged, faulty carburetor float needle and seat, pilot jet too large, fuel injectors leaking, smoke while riding is usually caused by the main jet being too large or a damaged carburetor.
It should be noted that aggressive or abnormal throttle operation will cause these conditions to manifest themselves exponentially.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the links below. Good luck and have a nice day.
smoke out the exhaust CBR Forum Enthusiast forums for Honda CBR Owners
Honda VT250 FII Shop Manual
Honda VT250 FII Owner Manual
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