Kohler CH5 / CH6 — Carburetor Adjustment (Low Idle Speed and Fuel)
Adjustments
For the Kohler CH5 / CH6, from the Kohler service manual.
Applies to: Kohler CH6
Before you start
- Carburetor adjustments should be made only after engine has warmed up.
Procedure
- With engine stopped, turn low idle fuel adjusting needle in until it bottoms lightly.
- Turn needle counterclockwise 1-1/4 turns open for idle fuel; main fuel (if adjustable) 1-1/8 turns open.
- Start engine and run at half throttle for 5-10 minutes to warm up.
- Main Fuel Needle Setting: Place throttle in fast position. Slowly turn main fuel needle clockwise until engine speed decreases, then back out about 1/4 turn.
- Low Idle Speed Setting: Place throttle in idle position. Check RPM with tachometer. Adjust low idle speed screw to 1200 +/- 75 RPM. Do not exceed 1500 RPM.
- Low Idle Fuel Setting: Move throttle to idle. Turn low idle fuel needle out until engine speed decreases (rich), note position, then turn in until speed increases then decreases (lean). Set needle mid
- Recheck low idle speed with tachometer and reset as needed.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Low idle fuel preliminary setting: 1-1/4 turns open
- Main fuel preliminary setting: 1-1/8 turns open (adjustable type only)
- Low idle speed: 1200 +/- 75 RPM, max 1500 RPM
- Fuel bowl retaining screw torque: 9.8 Nm (87 in. lb.)
- Throttle plate retaining screw torque: 0.9—1.4 Nm (8—12 in. lb.)
Full service-parts list: Kohler CH6 →
Source: Kohler service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.