Yamaha YZF R125 will not start , common problems and troubleshooting

SPARK/COMPRESSION/FUEL/AIR/TIMING

this is the basics of fault finding .

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You need all of the above to get the engine to run.

Remove the plug, reconnect it to the HT lead, hold it on the cylinder whilst turning the engine over and you should see a spark.

Whilst plug is out do a compression test. use a decent compression gauge to do the test .

Check fuel is fresh and getting to the carb.

thoroughly clean the carb out 

Check air filter is clean.

check timing spark problem - duff plug, cap, ht lead, coil - CDI , check timing .

Try the obvious first.


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