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Triumph · Overhead-cam four-stroke twin, wet sump, gearbox shares engine oil, chain drive

Bonneville T120

Library entry covers 2016-2025

45 factory 38 guideline

Published source

Triumph Modern Classics Owner's Handbook 3855663-EN, Scheduled Maintenance Table pp.99-100 (factory PDF hosted on a retailer CDN)

Factory owner's handbook. Covers Liquid-cooled Modern Classics (T100, T120, Speed Twin, Street Twin, Street Scrambler, Thruxton RS), handbook 3855663-EN issue 1, 08.2019.

83 items for a 2021 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: Four-stroke
Engine lubrication: Wet sump (oil in crankcase)
Oil filtration: Replaceable cartridge or spin-on filter
Valve gear: Overhead cam, screw/locknut adjusters
Ignition: Electronic (CDI / transistor / ECU)
Charging: Alternator / stator with rectifier
Battery: Wet cell (flooded lead-acid, needs topping up)
Fuel system: Fuel injection
Cooling: Liquid cooled
Primary drive: Gear or chain inside engine, shares engine oil
Gearbox oil: Shares engine oil
Clutch control: Hand lever, cable
Final drive: Chain
Front suspension: Telescopic fork
Rear suspension: Swingarm, twin shocks
Front brake: Disc, hydraulic
Rear brake: Disc, hydraulic
Wheels: Spoked, tubed
Sidecar: No sidecar

Maintenance schedule

2021 Triumph Bonneville T120

On the road: every 200 mi

2 items

Check engine oil level

Pre-ride / on the road

Guideline

Each fuel stop on old machines. Dry sump: check the tank hot, engine idling or just stopped, per your manual.
Lubricate drive chain

Pre-ride / on the road

Factory

Manual: Drive chain - lubricate. Factory: Every 200 miles (300 km).

On the road: every 300 mi

2 items

Check lights, horn, brake light switches

Pre-ride / on the road

Guideline
Check tire pressures

Pre-ride / on the road

Guideline

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 500 mi

1 item

Inspect chain and sprockets for wear (measure stretch)

Final drive

Factory

Manual: Drive chain - wear check. Factory: Every 500 miles (800 km).

Every 3,000 mi or 12 months

4 items

Check throttle cable(s) free play and return

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 fork seals, stanchions and fork boots

Front end

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

Rear suspension and frame

Guideline

Every 4,000 mi or 12 months

1 item

Inspect, clean and gap spark plugs

Engine

Guideline

Every 6,000 mi or 12 months

7 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.
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 8,000 mi or 2 years

1 item

Check and adjust valve clearances

Engine

Guideline

Every 10,000 mi or 12 months

29 items

All lights, instruments and electrical systems - check

Engine

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Autoscan - Carry out a full Autoscan using the Triumph Diagnostic Tool (print a customer copy)

Engine

Factory

Factory: As printed: - • • • • • (all five service columns marked: First Service, Annual Service and every mileage column)
Bank angle indicators - inspect visually for wear

Engine

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Carry out road test

Engine

Factory

Factory: As printed: - • • • • • (all five service columns marked: First Service, Annual Service and every mileage column)
Change engine oil

Engine

Factory

Manual: Engine oil - renew. Factory: First service 600 mi (1,000 km)/6 months; then every 10,000 mi (16,000 km) or yearly.
Complete the service record book and reset the service indicator (if fitted)

Engine

Factory

Factory: As printed: - • • • • • (all five service columns marked: First Service, Annual Service and every mileage column)
Coolant level - check/adjust

Engine

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Cooling system - check for leaks

Engine

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Engine - check for leaks

Engine

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Fasteners - inspect visually for security

Engine

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Front and rear suspension - check for damage/leaks/smooth operation

Engine

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Instruments and engine ECM - check for latest calibration download using the Triumph diagnostic tool

Engine

Factory

Factory: As printed: - • • • • • (all five service columns marked: First Service, Annual Service and every mileage column)
Replace oil filter

Engine

Factory

Manual: Engine oil filter - renew. Factory: Every 10,000 mi (16,000 km) or yearly.
Adjust clutch free play, lubricate cable and lever pivot

Primary and gearbox

Factory

Manual: Clutch cable - check function and adjust. Factory: Daily, and Every service: first, annual, 10,000/20,000/30,000/40,000 mi.
Check chain guard, chain oiler (if fitted), rear chain case

Final drive

Factory

Manual: Drive chain rubbing strip - check. Factory: Every service: first, annual, 10,000/20,000/30,000/40,000 mi.
Drive chain slack - check/adjust

Final drive

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Check steering head bearing adjustment

Front end

Factory

Manual: Headstock bearings - check/adjust. Factory: Every service: first, annual, 10,000/20,000/30,000/40,000 mi.
Steering - check for free operation

Front end

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Carry out all outstanding Service Bulletin and warranty work

Rear suspension and frame

Factory

Factory: As printed: - • • • • • (all five service columns marked: First Service, Annual Service and every mileage column)
Grease and check center / side stand and springs

Rear suspension and frame

Factory

Manual: Side stand/Center stand - lubricate/check operation. Factory: Daily, and Every service: first, annual, 10,000/20,000/30,000/40,000 mi.
Brake calipers - check for fluid leaks and seized pistons

Brakes

Factory

Factory: As printed: - • • • • • (all five service columns marked: First Service, Annual Service and every mileage column)
Brake fluid levels - check

Brakes

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Brake master cylinders - check for fluid leaks

Brakes

Factory

Factory: As printed: - • • • • • (all five service columns marked: First Service, Annual Service and every mileage column)
Check brake pads and discs

Brakes

Factory

Manual: Brake pads - check wear levels. Factory: Daily, and Every service: first, annual, 10,000/20,000/30,000/40,000 mi.
Check spoke tension and wheel true

Wheels and tires

Factory

Manual: Wheels - check spokes and tightness (spoked wheels only). Factory: Daily, and Every service: first, annual, 10,000/20,000/30,000/40,000 mi.
Check wheel bearings for play

Wheels and tires

Factory

Manual: Wheel bearings - check for wear/smooth operation. Factory: Every service: first, annual, 10,000/20,000/30,000/40,000 mi.
Inspect tire tread, sidewalls and date codes

Wheels and tires

Factory

Manual: Tire wear/tire damage - check. Factory: Daily, and Every service: first, annual, 10,000/20,000/30,000/40,000 mi.
Tire pressures - check/adjust

Wheels and tires

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check
Wheels - inspect for damage

Wheels and tires

Factory

Factory: As printed: Day • • • • • (all five service columns marked: First Service, Annual Service and every mileage column); 'Day' = also a daily check

Every 10,000 mi or 2 years

1 item

Compression test (or leak-down)

Engine

Guideline

Every 10,000 mi

6 items

Cooling system - check hoses for chafing/cracks/damage. Replace if necessary

Engine

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 10,000, 20,000, 30,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Throttle bodies - balance - 1200 cc engines only

Engine

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 10,000, 20,000, 30,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Throttle body plate (butterfly) - check/clean

Engine

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 10,000, 20,000, 30,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Air cleaner - renew

Fuel and air

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 10,000, 20,000, 30,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Fuel system - check for leaks, chafing etc.

Fuel and air

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 10,000, 20,000, 30,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Side stand pivot pin - clean/grease

Rear suspension and frame

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 10,000, 20,000, 30,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)

Every 12,000 mi or 2 years

3 items

Replace air filter element

Fuel and air

Guideline
Synchronize throttle bodies

Fuel and air

Guideline
Grease swingarm pivot

Rear suspension and frame

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 20,000 mi

5 items

Headstock bearings - lubricate

Engine

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 20,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Spark plugs - renew

Engine

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 20,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Valve clearances - check

Engine

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 20,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Fuel filter - renew

Fuel and air

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 20,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)
Camshaft timing

Ignition and electrics

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 20,000 and 40,000 mi. (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)

Every 24,000 mi or 4 years

1 item

Replace fuel filter

Fuel and air

Guideline

Every 25,000 mi or 6 years

1 item

Replace swingarm bushes / bearings

Rear suspension and frame

Guideline

Every 30,000 mi or 6 years

1 item

Rebuild forks: seals, bushes, springs

Front end

Guideline

Every 40,000 mi

1 item

Fork oil - renew

Front end

Factory

Factory: Scheduled maintenance table pp.99-100 (columns: every; first service 600 mi (1000 km) / 6 months; annual service; 10,000 and 30,000 mi (16,000 and 48,000 km); 20,000 mi (32,000 km); 40,000 mi (64,000 km)): marked at 40,000 mi (64,000 km). (Read from ManualsLib, Triumph Bonneville T100 Series owner's handbook pp.99-100, the same Modern Classics handbook as the source.)

Every 6 months

1 item

Clean battery terminals, check charge and strap

Ignition and electrics

Guideline

Every 2 years

3 items

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

Factory

Manual: Brake fluid - renew. Factory: Every 2 years regardless of mileage.

Every 3 years

1 item

Replace coolant

Engine

Factory

Manual: Coolant - renew. Factory: Every 3 years regardless of mileage.

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

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.