Chrysler 4 HP Outboard Motor Service Manual OB 2278, Page 12Get this manual
SECTION IV (Con't 3-2Adjusting Carburetor
ATurn idle adjustment screw in (clockwise) until it seats tightlyDO NOT FORCE IDLE ADJUSTMENT SCREW or the tip may be damagedSee figure 10 for location of idle screwFTurn the idle adjustment screw counter-clockwise until the engine begins to "roll and gallop" from the rich fuel! air settingNote position of screwdriver at this pointGTurn idle adjustment screw to midpoint between settings noted in steps and FH Do not adjust leaner than necessary to obtain smooth idlingIt is better to have the idle setting little rich than too leanIBOpen idle adjustment screw one turn coun ter-clockwise
It is not necessary to remove engine cover to adjust idle screwIt can be adjusted through opening in support plate
The high speed adjustment lever is located under the support plateTurn to right to make leaner, turn to left to make richer