How to Troubleshoot No Spark on a YZ250
Knowing how to troubleshoot systems effectively can get your motorcycle up and running again. Owners who have discovered the lack of a spark in the ignition system of the Yamaha YZ250 can use a number of different troubleshooting tactics that are recommended by Yamaha. While the company does not provide an online manual for this particular bike, it recommends that owners assess, adjust or diagnose possible ignition problems in a similar manner for all Yamaha dirt bikes.
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Instructions
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1
Access the spark plug cap and spark plug, located inside the YZ250's single cylinder.
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2
Remove the spark plug cap and spark plug by tugging on the cap and nudging it left and right until the plug slides out of the cylinder.
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3
Unscrew and remove the spark plug using a spark plug wrench.
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4
Examine the insulator tip at the end of the spark plug. If it is dry, burnt or cracked, take the bike to a Yamaha dealer for more serious repairs. If the insulator is wet and medium-brown in color, wipe the tip clean with a dry rag and move on to the next step.
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Measure the spark plug gap using a wire gap gauge. The gap should measure between 0.024 and 0.028 inch. Set the spark plug gap to this distance if it is too wide or too small. Press the hook-end of the spark plug against a firm, flat surface to shorten the spark plug gap to this width, or gently pull the hook end wider to lengthen the gap.
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6
Reinstall the spark plug using the spark plug wrench and press the spark plug cap back in place. Try the electric starter once more. If there is still no spark, take the bike to a Yamaha dealer for assessment and repairs.
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Tips & Warnings
Yamaha recommends that all owners take vehicles to certified Yamaha dealers for serious repairs, as these professionals have the tools and knowledge to repair Yamaha bikes without damage.
Do not attempt to ride the YZ250 if the spark plug was blackened or dry, as this is indicative of further engine problems and could damage the bike.
References
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