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KTM · Two-stroke single, premix, chain drive

EXC 300

Library entry covers 1995-2025

54 factory 58 guideline

Published source

KTM 300 EXC 2021 Owner's Manual 3214221en, Service schedule 10.2 Required work and 10.3 Recommended work, printed pp.45-46 (ManualsLib 3063039 pages 47-48)

Factory owner's handbook. Covers KTM 300 EXC 2021 owner's manual 3214221en; operating-hours service schedule (required and recommended work).

112 items for a 2025 model, grouped by interval the way a factory chart is laid out.

How this bike is built (what the schedule is based on)

Engine cycle: Two-stroke
Engine lubrication: Two-stroke premix (oil in fuel)
Oil filtration: None (no filter)
Valve gear: None (two-stroke porting)
Ignition: Magneto (incl. magdyno, flywheel magneto)
Charging: Alternator / stator with rectifier
Battery: Wet cell (flooded lead-acid, needs topping up)
Fuel system: Single carburetor
Cooling: Liquid cooled
Primary drive: Gear or chain inside engine, shares engine oil
Gearbox oil: Separate gearbox oil
Clutch control: Hand lever, cable
Final drive: Chain
Front suspension: Telescopic fork
Rear suspension: Swingarm, single shock / cantilever
Front brake: Disc, hydraulic
Rear brake: Disc, hydraulic
Wheels: Spoked, tubed
Sidecar: No sidecar

Maintenance schedule

2025 KTM EXC 300

On the road: every 200 km

1 item

Check two-stroke oil tank / carry premix oil

Pre-ride / on the road

Guideline

Running a two-stroke out of oil seizes it. Injection bikes: check the tank. Premix: carry oil and a measure.

On the road: every 500 km

3 items

Check lights, horn, brake light switches

Pre-ride / on the road

Guideline
Check tire pressures

Pre-ride / on the road

Guideline
Lubricate drive chain

Pre-ride / on the road

Guideline

Lube warm, ideally at the end of the riding day so it soaks in overnight. Sooner after rain.

On the road: every 800 km

1 item

Check coolant level

Pre-ride / on the road

Guideline

On the road: every 1,000 km

1 item

Check chain slack and rear wheel alignment

Pre-ride / on the road

Guideline

Every 1,600 km or 6 months

1 item

Inspect tire tread, sidewalls and date codes

Wheels and tires

Guideline

Every 3,000 km or 12 months

1 item

Replace spark plugs (two-stroke)

Engine

Guideline

Every 5,000 km or 12 months

13 items

Check throttle cable(s) free play and return

Fuel and air

Guideline
Clean fuel tap filter / sediment bowl

Fuel and air

Guideline
Check / set ignition timing

Ignition and electrics

Guideline
Clean and gap contact breaker points, oil cam felt

Ignition and electrics

Guideline
Clean drive chain thoroughly (remove and soak, re-lube)

Final drive

Guideline

Non O-ring chains on old machines: remove, clean, soak in hot chain grease or lube, refit with the master link clip closed end leading.
Inspect chain and sprockets for wear (measure stretch)

Final drive

Guideline
Check steering head bearing adjustment

Front end

Guideline
Inspect fork seals, stanchions and fork boots

Front end

Guideline
Check footrests, pegs, rear brake and gear lever pivots

Rear suspension and frame

Guideline
Grease and check center / side stand and springs

Rear suspension and frame

Guideline
Check brake pads and discs

Brakes

Guideline
Check spoke tension and wheel true

Wheels and tires

Guideline
Check wheel bearings for play

Wheels and tires

Guideline

Every 5,000 km or 2 years

1 item

Decarbonize exhaust ports, pipes and baffles

Engine

Guideline

Two-strokes coke up the exhaust port and muffler baffles; power falls off gradually.

Every 6,500 km or 12 months

2 items

Inspect, clean and gap spark plugs

Engine

Guideline
Adjust clutch free play, lubricate cable and lever pivot

Primary and gearbox

Guideline

Every 9,500 km or 12 months

8 items

Inspect coolant hoses and clamps

Engine

Guideline
Clean / inspect air filter

Fuel and air

Guideline

Mesh or oiled foam: clean and re-oil. Paper: blow out or replace. Some very early machines have no filter at all.
Clean carburetor float bowl(s), check float level and jets

Fuel and air

Guideline

Ethanol fuel varnishes old carbs quickly in storage.
Check charging voltage and regulator / cut-out

Ignition and electrics

Guideline
Check swingarm bushes for play

Rear suspension and frame

Guideline
Inspect rear shocks for leaks and damping

Rear suspension and frame

Guideline
Lubricate control cables and lever pivots

Controls and cables

Guideline
Lubricate speedometer / tachometer cables, check drive

Controls and cables

Guideline

A dry speedo cable whips the needle and eventually kills the instrument.

Every 9,500 km or 2 years

2 items

Lubricate and check automatic advance unit

Ignition and electrics

Guideline
Magneto: clean slip ring and pickup brush, check HT lead

Ignition and electrics

Guideline

Every 16,000 km or 2 years

2 items

Compression test (or leak-down)

Engine

Guideline
Change gearbox oil

Primary and gearbox

Guideline

Every 19,500 km or 2 years

3 items

Replace air filter element

Fuel and air

Guideline
Clean and grease rear suspension linkage

Rear suspension and frame

Guideline
Grease swingarm pivot

Rear suspension and frame

Guideline

Every 19,500 km or 3 years

1 item

Replace points and condenser

Ignition and electrics

Guideline

Every 24,000 km or 3 years

1 item

Change fork oil

Front end

Guideline

Some early telescopic forks are grease filled or use very small oil quantities. Check your manual.

Every 25,500 km or 4 years

1 item

Replace spark plugs

Engine

Guideline

Every 29,000 km

1 item

Replace chain and sprockets (wear based)

Final drive

Guideline

Every 32,000 km or 4 years

2 items

Repack / replace steering head bearings

Front end

Guideline

Many old machines use loose balls in cups and cones. Taper roller conversions are common.
Repack / replace wheel bearings

Wheels and tires

Guideline

Cup-and-cone and taper roller hubs need periodic repacking and adjustment.

Every 40,000 km or 6 years

1 item

Replace swingarm bushes / bearings

Rear suspension and frame

Guideline

Every 40,000 km or 10 years

1 item

Magneto overhaul / re-magnetize, replace capacitor

Ignition and electrics

Guideline

Weak spark when hot is the classic symptom. Old capacitors fail with age, not miles.

Every 48,500 km or 6 years

1 item

Rebuild forks: seals, bushes, springs

Front end

Guideline

Every 20 h

37 items

Change the glass fiber yarn filling in the main muffler

Engine

Factory

Factory: Service schedule 10.2 Required work (p.46): every 20 operating hours; every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Check that the electrical system is functioning properly

Engine

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the antifreeze and coolant level

Engine

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the headlight setting

Engine

Factory

Factory: Service schedule 10.2 Required work (p.46): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the idle speed

Engine

Factory

Factory: Service schedule 10.2 Required work (p.46): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the reed valve housing, reed valve and intake flange

Engine

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the rim run-out

Engine

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the tightness of the easily accessible, safety-relevant screws and nuts

Engine

Factory

Factory: Service schedule 10.2 Required work (p.46): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Final check: check the vehicle for operating safety and take a test ride

Engine

Factory

Factory: Service schedule 10.2 Required work (p.46): after 1 operating hour (one-time); after 5 operating hours (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Make a service entry in KTM Dealer.net

Engine

Factory

Factory: Service schedule 10.2 Required work (p.46): after 1 operating hour (one-time); after 5 operating hours (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check all hoses (e.g. fuel, cooling, bleeder, drainage, etc.) and sleeves for cracking, leaks, and incorrect routing

Fuel and air

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Clean the air filter and air filter box

Fuel and air

Factory

Factory: Service schedule 10.2 Required work (p.46): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check and charge the 12-V battery

Ignition and electrics

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check/correct the fluid level of the hydraulic clutch

Primary and gearbox

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the chain tension

Final drive

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the chain, rear sprocket, engine sprocket, and chain guide

Final drive

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Grease all moving parts (e.g. side stand, hand lever, chain, etc.) and check for smooth operation

Final drive

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check steering head bearing play

Front end

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the fork bearing for play

Front end

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the link fork

Front end

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the frame

Rear suspension and frame

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the shock absorber heim joint for play

Rear suspension and frame

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the brake discs

Brakes

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the brake lines for damage and leakage

Brakes

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the brake linings of the rear brake

Brakes

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the free travel of the foot brake lever

Brakes

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the free travel of the hand brake lever

Brakes

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the front brake fluid level

Brakes

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the front brake linings

Brakes

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the rear brake fluid level

Brakes

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the spoke tension

Wheels and tires

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the tire condition

Wheels and tires

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the wheel bearing for play

Wheels and tires

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the wheel hubs

Wheels and tires

Factory

Factory: Service schedule 10.2 Required work (p.45): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check tire pressure

Wheels and tires

Factory

Factory: Service schedule 10.2 Required work (p.45): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check that the throttle cables are undamaged, routed without sharp bends, and set correctly

Controls and cables

Factory

Factory: Service schedule 10.2 Required work (p.46): after 1 operating hour (one-time); every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the cables for damage and for routing without kinks

Controls and cables

Factory

Factory: Service schedule 10.2 Required work (p.46): every 20 operating hours; every 40 operating hours; every 10 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.

Every 40 h or 12 months

1 item

Change the needle jet (recommended)

Engine

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 12 months; every 48 months; every 40 operating hours; every 80 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.

Every 40 h

5 items

Change the gear oil

Engine

Factory

Factory: Service schedule 10.2 Required work (p.45): after 5 operating hours (one-time); every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Change the spark plug and spark plug connector

Engine

Factory

Factory: Service schedule 10.2 Required work (p.45): every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Perform minor engine service: check the exhaust control for functioning and smooth operation, check the clutch (recommended)

Primary and gearbox

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 40 operating hours; every 80 operating hours; every 10 operating hours when used for motorsports; every 40 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Service the fork

Front end

Factory

Factory: Service schedule 10.2 Required work (p.46): every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.
Perform the shock absorber service

Rear suspension and frame

Factory

Factory: Service schedule 10.2 Required work (p.46): every 40 operating hours. Legend: open circle = one-time interval; filled circle = periodic interval.

Every 80 h or 12 months

1 item

Check/adjust the carburetor components (recommended)

Fuel and air

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 12 months; every 48 months; every 80 operating hours; every 40 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.

Every 80 h

3 items

Change the piston and check the cylinder (recommended)

Engine

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 80 operating hours; every 40 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Check the electric starter drive (recommended)

Engine

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 80 operating hours; every 40 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.
Perform major engine service including removing and installing engine: change the connecting rod, conrod bearing and crank pin, check the transmission and shift mechanism, change all engine bearings (recommended)

Primary and gearbox

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 80 operating hours; every 40 operating hours when used for motorsports. Legend: open circle = one-time interval; filled circle = periodic interval.

Every 6 months

1 item

Clean battery terminals, check charge and strap

Ignition and electrics

Guideline

Every 12 months

4 items

Change the hydraulic clutch fluid (recommended)

Primary and gearbox

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 12 months; every 48 months. Legend: open circle = one-time interval; filled circle = periodic interval.
Lubricate the steering head bearing (recommended)

Front end

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 12 months; every 48 months. Legend: open circle = one-time interval; filled circle = periodic interval.
Change the front brake fluid (recommended)

Brakes

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 12 months; every 48 months. Legend: open circle = one-time interval; filled circle = periodic interval.
Change the rear brake fluid (recommended)

Brakes

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 12 months; every 48 months. Legend: open circle = one-time interval; filled circle = periodic interval.

Every 2 years

4 items

Replace coolant

Engine

Guideline
Inspect wiring, bullet connectors and ground points

Ignition and electrics

Guideline
Inspect frame, welds and lugs for cracks

Rear suspension and frame

Guideline
Replace brake fluid

Brakes

Guideline

Every 4 years

4 items

Change the coolant (recommended)

Engine

Factory

Factory: Service schedule 10.3 Recommended work (p.46): every 48 months. Legend: open circle = one-time interval; filled circle = periodic interval.
Replace fuel lines

Fuel and air

Guideline

Old rubber and modern ethanol fuel do not mix well.
Inspect brake hoses; replace old rubber

Brakes

Guideline
Rebuild calipers and master cylinders (seals)

Brakes

Guideline

Every 6 years

2 items

Replace inner tubes and rim tape with tires

Wheels and tires

Guideline
Replace tires on age (regardless of tread)

Wheels and tires

Guideline

No interval set

2 items

Service the fork (recommended, one-time)

Front end

Factory

Factory: Service schedule 10.3 Recommended work (p.46): after 10 operating hours (one-time). Legend: open circle = one-time interval; filled circle = periodic interval.
Perform the shock absorber service (recommended, one-time)

Rear suspension and frame

Factory

Factory: Service schedule 10.3 Recommended work (p.46): after 20 operating hours (one-time). Legend: open circle = one-time interval; filled circle = periodic interval.

Guideline lines: Intervals here are general guidelines for the machine's era and layout, compiled for this app. They are not factory manual figures. Check your workshop manual, and edit any interval in the bike's Schedule tab.