Yamaha R3 2021 Owner's Manual

Also see for R3 2021: Owner's manual

Periodic maintenance and adjustment7-107EAU19643Checking the spark plugsThe spark plugs are important enginecomponents, which should bechecked periodically, preferably by aYamaha dealer. Since heat and depos-its will cause any spark plug to slowlyerode, they should be removed andchecked in accordance with the peri-odic maintenance and lubricationchart. In addition, the condition of thespark plugs can reveal the condition ofthe engine.The porcelain insulator around thecenter electrode of each spark plugshould be a medium-to-light tan (theideal color when the vehicle is riddennormally), and all spark plugs installedin the engine should have the samecolor. If any spark plug shows a dis-tinctly different color, the engine couldbe operating improperly. Do not at-tempt to diagnose such problemsyourself. Instead, have a Yamaha deal-er check the vehicle.If a spark plug shows signs of elec-trode erosion and excessive carbon orother deposits, it should be replaced.Before installing a spark plug, thespark plug gap should be measuredwith a wire thickness gauge and, ifnecessary, adjusted to specification.Clean the surface of the spark pluggasket and its mating surface, andthen wipe off any grime from the sparkplug threads.TIPIf a torque wrench is not availablewhen installing a spark plug, a goodestimate of the correct torque is 1/4–1/2 turn past finger tight. However, thespark plug should be tightened to thespecified torque as soon as possible.Specified spark plug:NGK/CR8E1. Spark plug gapSpark plug gap:0.7–0.8 mm (0.028–0.031 in)Tightening torque:Spark plug:13 N·m (1.3 kgf·m, 9.6 lb·ft)