Kohler KT21 Engine

1. Loosen the cover retaining screws.
2. Shift the cover in clockwise direction for richer setting or counterclockwise direction for leaner setting.
3. Tighten the cover retainer screws.

Tools: Feeler gauge, Screwdriver

1. Loosen point gap adjustment screw.
2. Readjust gap to .020" fully open.
3. Gap may vary .017"-.023" to achieve smoothest running.
4. Securely tighten adjusting screw after timing.

Tools: Pliers, Wrench

1. With pliers, turn governor cross shaft clockwise as far as it will go.
2. Pull governor arm back away from carburetor as far as it will go.
3. Tighten governor clamp nut.

⚠ Never tamper with governor settings to increase maximum speed of the engine.

Tools: Hand tachometer, Screwdriver

1. Check operating speed with a hand tachometer; do not exceed 3600 RPM no load.
2. If adjustment needed, loosen the governor speed adjusting screw.
3. Pivot the high speed stop tab until desired speed setting is reached.
4. Tighten the screw.

Tools: ohmmeter or continuity tester, feeler gauge

1. Make sure ignition switch is off. Completely disconnect spark plug leads from plugs.
2. Remove breaker point cover, connect an ohmmeter or continuity tester from breaker point terminal to ground.
3. Rotate the engine by hand in direction of normal rotation (clockwise viewed from flywheel end).
4. When points are just breaking, the S mark on the flywheel should be directly opposite the roll pin in the #1 cylinder barrel.
5. If S is above or below roll pin, adjust point gap in or out until S mark is directly opposite the roll pin.
6. If no ohmmeter, measure gap with feeler gauge; gap should be .020 inch fully open.

Tools: timing light

1. Remove high tension lead at spark plug; wrap one end of a short piece of fine wire around spark plug terminal and reconnect lead.
2. Connect one timing light lead to the wire wrapped around the spark plug terminal.
3. Connect second timing light lead to hot (ungrounded) side of battery; connect third lead to ground.
4. Start engine, run at 1200-1800 RPM, aim timing light into sight hole; light should flash just as S mark is opposite the roll pin.
5. If timing is off, remove breaker point cover; loosen gap adjusting screw and shift breaker plate until S mark is exactly centered, then retighten.
6. Check timing before replacing breaker point cover.

⚠ Make sure ignition switch is off and spark plug leads disconnected to prevent unintentional starting.

Tools: Ohmmeter or continuity tester, Feeler gauge, Screwdriver

1. Make sure ignition switch is off and disconnect spark plug leads.
2. Remove breaker point cover; connect ohmmeter or continuity tester from breaker point terminal to ground.
3. Rotate engine by hand clockwise (viewed from flywheel end) until points just begin to break.
4. When points just break, the S mark on flywheel should be directly opposite the roll pin in the #1 cylinder barrel.
5. If S is above or below the roll pin, adjust point gap until S mark is opposite the roll pin.
6. If no meter is available, set gap to .020" fully open; gap may vary .017"-.023" for smoothest running.

⚠ Breaker point cover screws must be screwed back into mounting pad to keep oil from squirting out while timing.

Tools: Timing light, Screwdriver

1. Remove high tension lead at spark plug and wrap fine wire around terminal; reconnect lead.
2. Connect one timing light lead to the wrapped wire.
3. Connect second lead to hot (ungrounded) side of battery.
4. Connect third lead to ground.
5. Start engine, run at 1200-1800 RPM, aim timing light into sight hole; light should flash as S mark is opposite roll pin.
6. If timing is off, remove breaker point cover, loosen gap adjusting screw, shift breaker plate until S mark centered, retighten.

⚠ Adjusting screw ends taper to critical valve; do not tighten forcefully.

Tools: Screwdriver

1. Stop engine; turn main fuel and idle fuel adjusting screws clockwise until they bottom lightly.
2. Preliminary: KT17/KT19 turn main fuel screw counterclockwise 2-1/2 turns from bottom.
3. Preliminary: KT21 turn main fuel screw counterclockwise 3 turns from bottom.
4. Preliminary: all KT models turn idle fuel screw counterclockwise 1 to 1-1/4 turns from bottom.
5. Final Main Fuel: run engine at half-throttle 5-10 minutes to warm up.
6. Turn main fuel screw clockwise from preliminary setting until speed decreases; note position.
7. Turn screw counterclockwise; note position where speed starts to decrease.
8. Set screw midway between the two noted positions.
9. Final Idle Fuel: allow speed to fall to idle; adjust same as main fuel.
10. Idle Speed: run at half-throttle 5-10 minutes; set speed to 1200 RPM (+75 RPM).

1. Disconnect the high tension leads from spark plugs so the engine will not start.
2. Remove the air cleaner cover, element and base.
3. Push the start switch on the controller to the start position and hold for five seconds.
4. The choke should fully close and release when the start switch is released.
5. If the choke does not function properly, see the Service Guide.

Tools: Ohmmeter

1. If choke won't close when cranking: check faulty lead to choke for secure connections and continuity.
2. Check faulty lead to ground for secure connections and continuity.
3. If poor adjustment, adjust choke; if faulty, repair with kit or replace.
4. If choke will not fully open: adjust choke or repair with kit or replace.

Tools: Compression gauge

1. Remove spark plugs and insert compression gauge in each spark plug hole.
2. Set throttle and choke wide open and ensure intake and exhaust are not restricted.
3. Motor the engine using the starting motor.
4. Take several readings on both cylinders.