1971 Johnson 125HP outboards Service Manual, Page 100Get this manual
gConnect voltmeter between the green instrument cable lead and good ground at motorSee Figure 8-5Turn Key Switch to "ON" positionHave an assistant operate the control between forward, neutral, and reverse several timesVoltmeter must read battery voltage only when control is in neutral or reverseConnect voltmeter between blue lead and groundRepeat control operation as aboveVoltmeter should show battery voltage in reverse only
WARM-UP LEVER ADJUSTMENT
aCheck the safety switch adjustment on the motor as described in Section and reset if necessarybPlace control lever in NEUTRAL and warm-up lever in full START positionCrank motor with KEY switchIf starter doesn't crank, turn warm-up lever stop screw in (clockwise) until engagement takes placeSee Figure 8-6