Yamaha YZ250FM 2021 Owner's Service Manual

ELECTRICAL COMPONENTS8-46a. Disconnect the diode from the wire har-ness.b. Connect the digital circuit tester () to thediode coupler as shown.c. Check the diode for continuity.d. Check the diode for no continuity.EAM30294CHECKING THE IGNITION SPARK GAP1. Check:• Ignition spark gapOut of specification  Perform the ignitionsystem troubleshooting, starting with step (5).Refer to “TROUBLESHOOTING” on page8-3.TIPIf the ignition spark gap is within specification,the ignition system circuit is operating normally.a. Remove the spark plug cap from the sparkplug.b. Connect the ignition checker “1” asshown.c. Crank the engine, and measure the igni-tion spark gap “a”.d. Crank the engine, and gradually increasethe spark gap until a misfire occurs.EAM30295CHECKING THE SPARK PLUG CAP1. Remove:• Spark plug cap(from the spark plug lead)2. Check:• Spark plug cap resistanceOut of specification  Replace.a. Connect the digital circuit tester () to thespark plug cap.No continuityTester positive lead Blue/Green “1”Tester negative lead  Blue “2”ContinuityTester positive lead  Blue “2”Tester negative lead Blue/Green “1”No continuityTester positive lead Brown/White, Brown “3”Tester negative lead Blue/Green, Blue/White “4”ContinuityTester positive lead Blue/Green, Blue/White “4”Tester negative lead Brown/White, Brown “3”No continuityTester positive prove Blue/Black “5”Tester negative prove Blue/Red “6”ContinuityTester positive prove Blue/Red “6”Tester negative prove Blue/Black “5”A. Diode 1B. Diode 2C. Diode 3L/GLL/BL/RBr/W,BrL/G,L/W123456Minimum ignition spark gap6.0 mm (0.24 in)Ignition checker90890-06754Oppama pet–4000 spark checkerYM-344872. Spark plug capResistance7.50–12.50 kDigital circuit tester (CD732)90890-03243Model 88 Multimeter with tachom-eterYU-A1927