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Sherco · Two-stroke single, premix, chain drive

ST 300

Library entry covers 2009-2025

33 factory 52 guideline

Published source

Sherco Owner's Manual Trial 125-250-300 ST-F-Factory (multilingual), English maintenance schedule printed pp.69-70

Factory source. Covers Sherco Owner's Manual Trial 125-250-300 ST / ST Factory (official PDF, file named 2025; no year printed in the pages read); earlier years not compared.

85 items for a 2020 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: Electronic (CDI / transistor / ECU)
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

2020 Sherco ST 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

11 items

Check throttle cable(s) free play and return

Fuel and air

Guideline
Clean fuel tap filter / sediment bowl

Fuel and air

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 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 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 48,500 km or 6 years

1 item

Rebuild forks: seals, bushes, springs

Front end

Guideline

Every 20 h

25 items

Accelerator grip play (check)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours, then every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Coolant level (check)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours, then every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Flap valve, spark plug and interference filter (check)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Headlight adjustment (check)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Nuts and bolts (check tightness)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours, then every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Suspension rod slack (check)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Tubes and dust covers (inspect for cracks and leaks)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Wires (check)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Air filter and air filter housing (clean)

Fuel and air

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Clutch (check)

Primary and gearbox

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Gearbox oil (replace)

Primary and gearbox

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours; marks also at every 20, 60 and 100 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Chain tension (check)

Final drive

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours, then every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Final drive, chain, sprockets and chain guide (check)

Final drive

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Steering column slack (check)

Front end

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours, then every 20 hours. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Frame (check)

Rear suspension and frame

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Shock absorber attachments (check)

Rear suspension and frame

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours, then every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Shock absorber leaks (check)

Rear suspension and frame

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Swingarm and swingarm bearing slack (check)

Rear suspension and frame

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Brake and clutch fluid levels (check)

Brakes

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Brake pads, front brake discs and brake lines (check)

Brakes

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Front and rear brake pedal free clearance (check)

Brakes

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours, then every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Tire condition, rims and spoke tension (check)

Wheels and tires

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride; spokes also after the first 3 hours. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Tire pressure (check)

Wheels and tires

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): after the first 3 hours, then every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Wheel hubs and hub slack (check)

Wheels and tires

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Idle speed and throttle cable (check)

Controls and cables

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 20 hours and after each ride. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.

Every 60 h

2 items

Clutch spring (replace)

Primary and gearbox

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 60 hours. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Fork maintenance

Front end

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): marked at the 20 and 60 hour columns. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.

Every 100 h

1 item

Muffler steel wool (replace)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 100 hours. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.

Every 120 h

1 item

Engine maintenance: con rod, needle cage, crank pin cage, piston, cylinder check, gearbox and shift check, all engine bearings

Primary and gearbox

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 120 hours of use, or every 40 hours of competition use. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.

Every 6 months

1 item

Clean battery terminals, check charge and strap

Ignition and electrics

Guideline

Every 12 months

3 items

Clutch fluid (replace)

Primary and gearbox

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every year (also marked every 4 years). Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Steering column, swingarm and suspension rod bearings (lubricate)

Front end

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every year. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
Brake fluid (replace)

Brakes

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every year (also marked every 4 years). Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.

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

Coolant (replace)

Engine

Factory

Factory: Maintenance schedule (English section, printed pp.69-70): every 4 years. Columns as printed (p.69): after 3 hours, every 20, 60 and 100 hours of use, after each ride; (p.70): every 60 and 120 hours of use, every year, every 4 years, every 40 hours of competition use. Move the schedule up when riding on dusty roads.
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

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.