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KTM · Two-stroke single, premix, chain drive

SX 50

Library entry covers 1995-2025

48 factory 58 guideline

Published source

KTM 50 SX 2009 Owner's Manual 3211344en, Service schedule pp.19-20

Factory owner's handbook. Covers 2009 KTM 50 SX / Junior / Mini owner's manual 3211344en; other years not compared.

106 items for a 2010 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: Automatic or semi-automatic
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

2010 KTM SX 50

On the road: every 150 mi

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 300 mi

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 500 mi

1 item

Check coolant level

Pre-ride / on the road

Guideline

On the road: every 600 mi

1 item

Check chain slack and rear wheel alignment

Pre-ride / on the road

Guideline

Every 1,000 mi or 6 months

1 item

Inspect tire tread, sidewalls and date codes

Wheels and tires

Guideline

Every 2,000 mi or 12 months

1 item

Replace spark plugs (two-stroke)

Engine

Guideline

Every 3,000 mi or 12 months

14 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
Adjust automatic / semi-automatic clutch

Primary and gearbox

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 3,000 mi 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 4,000 mi or 12 months

1 item

Inspect, clean and gap spark plugs

Engine

Guideline

Every 6,000 mi 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 6,000 mi 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 10,000 mi or 2 years

2 items

Compression test (or leak-down)

Engine

Guideline
Change gearbox oil

Primary and gearbox

Guideline

Every 12,000 mi 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 12,000 mi or 3 years

1 item

Replace points and condenser

Ignition and electrics

Guideline

Every 15,000 mi 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 16,000 mi or 4 years

1 item

Replace spark plugs

Engine

Guideline

Every 18,000 mi

1 item

Replace chain and sprockets (wear based)

Final drive

Guideline

Every 20,000 mi 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 25,000 mi or 6 years

1 item

Replace swingarm bushes / bearings

Rear suspension and frame

Guideline

Every 25,000 mi 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 30,000 mi or 6 years

1 item

Rebuild forks: seals, bushes, springs

Front end

Guideline

Every 20 h

29 items

All screws (check tightness)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Connecting rod bearing radial clearance (check)

Engine

Factory

Factory: Service schedule 8.2 (pp.19-20): every 20 and 40 service hours. 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Crankshaft main bearing (check)

Engine

Factory

Factory: Service schedule 8.2 (pp.19-20): every 20 and 40 service hours. 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Cylinder and piston (check wear)

Engine

Factory

Factory: Service schedule 8.2 (pp.19-20): every 20 and 40 service hours. 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Engine mounting screws (check)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Exhaust system (check)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): check for leaks and looseness every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Idle (check)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Intake membrane (check wear)

Engine

Factory

Factory: Service schedule 8.2 (pp.19-20): every 20 and 40 service hours. 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Main muffler glass fiber filling (change)

Engine

Factory

Factory: Service schedule 8.2 (pp.19-20): every 20 and 40 service hours. 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Piston pin seating (check)

Engine

Factory

Factory: Service schedule 8.2 (pp.19-20): every 20 and 40 service hours. 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Rim runout (check)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Spark plug (check, replace if required)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Spark plug connector (clean, check tightness)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Air filter (clean)

Fuel and air

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Clutch engagement speed (check)

Primary and gearbox

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Clutch linings and clutch drum (check wear)

Primary and gearbox

Factory

Factory: Service schedule 8.2 (pp.19-20): every 20 and 40 service hours. 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Chain (clean)

Final drive

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Chain adjuster screws (clean, grease)

Final drive

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Chain wear and tension (check)

Final drive

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Fork dust boots (clean)

Front end

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Fork legs (bleed)

Front end

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Shock absorber and fork (check)

Front end

Factory

Factory: Service schedule 8.1 (pp.19-20): check for leaks and function every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Brake fluid level, front and rear (check)

Brakes

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Brake lever free play, hand and foot (check)

Brakes

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Brake system function (check)

Brakes

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Brake system screws and guide bolts (check)

Brakes

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Spoke tension (check)

Wheels and tires

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Tire condition and pressure (check)

Wheels and tires

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Wheel bearing play (check)

Wheels and tires

Factory

Factory: Service schedule 8.1 (pp.19-20): every 20 service hours (S20A) and every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).

Every 40 h

12 items

Antifreeze and coolant level (check)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Cooling system (check for leaks)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Crankshaft and connecting rod bearings (change)

Engine

Factory

Factory: Service schedule 8.2 (pp.19-20): every 40 service hours. 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Gear oil (change)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Vent hoses (check)

Engine

Factory

Factory: Service schedule 8.1 (pp.19-20): check for damage and routing without sharp bends every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Intake flange and carburetor boots (check)

Fuel and air

Factory

Factory: Service schedule 8.1 (pp.19-20): check for cracks and leaks every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Steering head bearing play (check)

Front end

Factory

Factory: Service schedule 8.1 (pp.19-20): every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Swingarm bearing (check)

Rear suspension and frame

Factory

Factory: Service schedule 8.1 (pp.19-20): every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Brake discs (check)

Brakes

Factory

Factory: Service schedule 8.1 (pp.19-20): every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Brake lines (check)

Brakes

Factory

Factory: Service schedule 8.1 (pp.19-20): check for damage and leaks every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Brake linings, front and rear (check)

Brakes

Factory

Factory: Service schedule 8.1 (pp.19-20): every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Control cables (check)

Controls and cables

Factory

Factory: Service schedule 8.1 (pp.19-20): check Bowden cables for damage, smooth operation and routing every 40 service hours (S40A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).

Every 6 months

1 item

Clean battery terminals, check charge and strap

Ignition and electrics

Guideline

Every 12 months

6 items

Carburetor (clean, adjust)

Fuel and air

Factory

Factory: Service schedule 8.2 (pp.19-20): annually (J1A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Fork (complete service)

Front end

Factory

Factory: Service schedule 8.2 (pp.19-20): annually (J1A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Steering head bearing (grease)

Front end

Factory

Factory: Service schedule 8.2 (pp.19-20): annually (J1A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Shock absorber (complete service)

Rear suspension and frame

Factory

Factory: Service schedule 8.2 (pp.19-20): annually (J1A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Swingarm bearing (clean, lubricate)

Rear suspension and frame

Factory

Factory: Service schedule 8.2 (pp.19-20): annually (J1A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).
Brake fluid, front and rear (change)

Brakes

Factory

Factory: Service schedule 8.2 (pp.19-20): annually (J1A). 8.1 and 8.2: important maintenance work to be carried out by an authorized KTM workshop (8.2 as an additional order).

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

3 items

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

1 item

Rider checks as conditions require

Engine

Factory

Factory: Service schedule 8.3 (p.20): urgent inspection and care by the supervising person, depending on conditions of use (NB1A): gear oil level, front and rear brake fluid levels and linings, Bowden cables, bleed fork legs, clean fork dust boots, clean the chain, chain tension and wear, sprocket wear, clean the air filter, tire pressure and condition, coolant level, smooth operation of all controls, braking, and tightness of all screws, nuts and hose clamps.

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.