1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 103Get this manual
ADJUSTING MAXIMUM SPARK ADVANCE IMPORTANT: Setting the idle timing is required before adjusting the maximum spark advance16Turn engine off17Position twist grip or remote control lever to maximum throttle opening, (wide open throttle)18Loosen jam nut and turn screw counter-clockwise until screw no longer makes contact with throttle bracket platform19Turn screw in (clockwise) until screw just makes contact with the throttle bracket platform and then give screw one (1) additional turn clockwise and tighten jam nut 21Adjust carburetor for best performance, after cle aring the engineWith engine running at idle spe ed in "F RWAge ar, turn mixture screw "IN(clockwise) until engine starts to loose R.P.M fire unevenly, and or misfiresB ack out 14 turn or more(S eneral Specifications for minimum and maximum adjustment)22C heck for too le an of mixture on acceleration(E ngine will "hesitateor "stallon acceleration)R adjust mixture if necessary23R e-adjust idle spe ed screw in "F RWA "ge ar to specification