1986-1989 Honda TRX250 FourTrax 250R Service Manual, Page 205Get this manual
ELECTRICAL SYSTEM
IGNITION TIMING
NOTE The COl unittiming is not adjustableIf the ignition timing is incorrect, check the ignition system (page 153) and replace any faulty partsIf all of the other components check out OK, replace the COl unitWarm up the engine to operating temperatureRemove the alternator coverConnect tachometer and timing lightStart the engine and allow it to idle
IDLE SPEED: 1,500 150 rpm Timing is correct if the index mark aligns with the "F" mark at idleGradually increase the engine speed and make sure that the index mark lines up between the "F" mark and "T" mark
AC REGULATOR
Remove the front fender (page 142): Oisconnectthe handlebar switch 3P connectorConnect tachometerStart the engine and measure the voltage between the White! Yellow and Green wire terminals at the wire harness side of the connector