1981-1984 Official Honda ATC250R Shop Manual, Page 19Get this manual
ATe 250R
MAINTENANCE
INDEX MARK
IGNITION TIMING
The ignition timing is not adjustableIf the ignition timing is incorrect, check the unit and generator and replace any faulty parts
IGNITION TIMING CHECK
Remove the generator coverTiming is correct if the index mark aligns with the "F" mark at 2,000 rpm IGNITION TIMING: 17 BTDC2,OOO rpm