Suzuki · Suzuki GS air-cooled four (GS400-GS1100 1976-1988)

GS400 / GS425 / GS450 / GS500 twin

Library entry covers 1977-2009

33 factory 38 guideline

Published source

Suzuki GS400 Owner's Manual (model GS400B), Suzuki part 99011-44600

Factory owner's handbook. Covers 1977 (GS400B owner's manual, printed August 1976).

Open the source

71 items for a 1977 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, shim adjusted (incl. desmo)
Ignition: Battery and coil with contact points
Charging: Alternator / stator with rectifier
Battery: Wet cell (flooded lead-acid, needs topping up)
Fuel system: Two or more carburetors
Cooling: Air / oil 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: Cast / alloy, tubeless
Sidecar: No sidecar

Maintenance schedule

1977 Suzuki GS400 / GS425 / GS450 / GS500 twin

On the road: every 200 mi

1 item

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.

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 600 mi

2 items

Check chain slack and rear wheel alignment

Pre-ride / on the road

Factory

Manual: Drive chain: adjust. Factory: Periodic inspection schedule p.79: adjust every 1,000 km (600 mi)
Lubricate drive chain

Pre-ride / on the road

Factory

Manual: Drive chain: lubricate. Factory: Lubrication schedule p.77: every 1,000 km (600 mi)

On the road: every 1,000 mi

1 item

Check road kit: plugs, points file, master link, tube patches, wire, tape

Pre-ride / on the road

Guideline

On the road: every 3,000 mi

1 item

Walk-around: check nuts and bolts for vibration loosening

Pre-ride / on the road

Factory

Manual: All nuts and bolts (engine and body): retighten. Factory: Periodic inspection schedule p.79: initial 1,000 km, then every 5,000 km

Every 1,500 mi or 6 months

1 item

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.

Every 1,500 mi

1 item

Change engine oil

Engine

Factory

Manual: Engine oil: change. Factory: Lubrication schedule p.77: initial 1,000 km (600 mi), then every 2,500 km

Every 3,000 mi or 12 months

10 items

Check engine mounting bolts and plates

Engine

Guideline
Clean fuel tap filter / sediment bowl

Fuel and air

Guideline
Check / set ignition timing

Ignition and electrics

Guideline
Adjust clutch pushrod / clutch adjuster

Primary and gearbox

Guideline
Check chain guard, chain oiler (if fitted), rear chain case

Final drive

Guideline
Inspect chain and sprockets for wear (measure stretch)

Final drive

Guideline
Check steering damper (friction or hydraulic)

Front end

Guideline
Inspect fork seals, stanchions and fork boots

Front end

Guideline
Grease and check center / side stand and springs

Rear suspension and frame

Guideline
Check wheel bearings for play

Wheels and tires

Guideline

Every 3,000 mi

18 items

Check and adjust valve clearances

Engine

Factory

Manual: Tappet clearance: check. Factory: Periodic inspection schedule p.78: initial 1,000 km, then every 5,000 km
Compression test (or leak-down)

Engine

Factory

Manual: Compression: check. Factory: Periodic inspection schedule p.78: initial 1,000 km, then every 5,000 km
Exhaust pipe and muffler: retighten

Engine

Factory

Factory: Periodic inspection schedule p.78: initial 1,000 km, then every 5,000 km
Inspect, clean and gap spark plugs

Engine

Factory

Manual: Spark plug: clean and adjust gap. Factory: Periodic inspection schedule p.78: every 5,000 km (3,000 mi)
Oil pressure: check

Engine

Factory

Factory: Periodic inspection schedule p.78: every 5,000 km (3,000 mi)
Replace oil filter

Engine

Factory

Manual: Oil filter: change. Factory: Periodic inspection schedule p.78: initial 1,000 km, then every 5,000 km
Check throttle cable(s) free play and return

Fuel and air

Factory

Manual: Throttle cable: adjust. Factory: Periodic inspection schedule p.79: initial 1,000 km, then every 5,000 km
Clean / inspect air filter

Fuel and air

Factory

Manual: Air cleaner element: clean. Factory: Periodic inspection schedule p.78: every 5,000 km (3,000 mi)
Synchronize carburetors

Fuel and air

Factory

Manual: Carburetor: adjust. Factory: Periodic inspection schedule p.78: initial 1,000 km, then every 5,000 km
Check battery electrolyte, top up with distilled water

Ignition and electrics

Factory

Manual: Battery: check. Factory: Periodic inspection schedule p.79: initial 1,000 km, then every 5,000 km
Clean and gap contact breaker points, oil cam felt

Ignition and electrics

Factory

Manual: Contact breaker point and timing: check and adjust. Factory: Periodic inspection schedule p.78: initial 1,000 km, then every 5,000 km
Contact breaker cam oil felt: motor oil

Ignition and electrics

Factory

Factory: Lubrication schedule p.77: every 5,000 km (3,000 mi)
Adjust clutch free play, lubricate cable and lever pivot

Primary and gearbox

Factory

Manual: Clutch: adjust. Factory: Periodic inspection schedule p.78: initial 1,000 km, then every 5,000 km
Check steering head bearing adjustment

Front end

Factory

Manual: Steering: check. Factory: Periodic inspection schedule p.79: initial 1,000 km, then every 5,000 km
Check footrests, pegs, rear brake and gear lever pivots

Rear suspension and frame

Factory

Manual: Brake pedal: grease or oil. Factory: Lubrication schedule p.77: every 5,000 km (3,000 mi)
Check brake pads and discs

Brakes

Factory

Manual: Brake system (front and rear): check. Factory: Periodic inspection schedule p.79: initial 1,000 km, then every 5,000 km
Inspect tire tread, sidewalls and date codes

Wheels and tires

Factory

Manual: Tire: check. Factory: Periodic inspection schedule p.79: every 5,000 km (3,000 mi)
Lubricate control cables and lever pivots

Controls and cables

Factory

Manual: Throttle cable and clutch cable: motor oil. Factory: Lubrication schedule p.77: every 5,000 km (3,000 mi)

Every 5,000 mi or 2 years

1 item

Check cylinder head bolt torque

Engine

Guideline

Air-cooled iron and alloy engines can lose head bolt tension; follow your manual's sequence and whether it is done hot or cold.

Every 6,000 mi or 12 months

5 items

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 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

3 items

Check engine breather and oil return

Engine

Guideline
Check valve clearances (shim adjusted)

Engine

Guideline
Lubricate and check automatic advance unit

Ignition and electrics

Guideline

Every 6,000 mi

5 items

Clean oil strainers / mesh screens

Engine

Factory

Manual: Oil sump filter: clean. Factory: Periodic inspection schedule p.78: every 10,000 km (6,000 mi)
Replace spark plugs

Engine

Factory

Manual: Spark plug: replace. Factory: Periodic inspection schedule p.78: every 10,000 km (6,000 mi)
Throttle grip: grease

Engine

Factory

Factory: Lubrication schedule p.77: every 10,000 km (6,000 mi)
Change fork oil

Front end

Factory

Manual: Front fork oil: change. Factory: Lubrication schedule p.77: initial 1,000 km, then every 10,000 km
Lubricate brake cam spindles, check linings and drums

Brakes

Factory

Manual: Brake cam shaft: grease. Factory: Lubrication schedule p.77: every 10,000 km (6,000 mi)

Every 10,000 mi

1 item

Replace chain and sprockets (wear based)

Final drive

Guideline

Every 12,000 mi or 2 years

5 items

Speedometer gear housing: grease

Engine

Factory

Factory: Lubrication schedule p.77: every 2 years or 20,000 km (12,000 mi)
Replace air filter element

Fuel and air

Guideline
Repack / replace steering head bearings

Front end

Factory

Manual: Steering stem bearings: grease. Factory: Lubrication schedule p.77: every 2 years or 20,000 km (12,000 mi)
Grease swingarm pivot

Rear suspension and frame

Factory

Manual: Swinging arm: grease. Factory: Lubrication schedule p.77: every 2 years or 20,000 km (12,000 mi)
Repack / replace wheel bearings

Wheels and tires

Factory

Manual: Wheel bearings: grease. Factory: Lubrication schedule p.77: every 2 years or 20,000 km (12,000 mi)

Every 12,000 mi or 3 years

1 item

Replace points and condenser

Ignition and electrics

Guideline

Every 15,000 mi or 5 years

1 item

Inspect clutch plates and springs

Primary and gearbox

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 6 months

1 item

Clean battery terminals, check charge and strap

Ignition and electrics

Guideline

Every 12 months

1 item

Check speedometer / odometer against a known distance

Controls and cables

Guideline

Old speedos drift with tire size and drive wear. Use phone GPS over a measured 10 miles / km.

Every 2 years

6 items

Inspect fuel tank for rust, sealer failure, leaks

Fuel and air

Guideline
Replace fuel lines

Fuel and air

Factory

Manual: Fuel hose: change. Factory: Periodic inspection schedule p.79: change every 2 years
Inspect wiring, bullet connectors and ground points

Ignition and electrics

Guideline
Inspect frame, welds and lugs for cracks

Rear suspension and frame

Guideline
Inspect brake hoses; replace old rubber

Brakes

Factory

Manual: Brake hose: change. Factory: Periodic inspection schedule p.79: change every 2 years
Replace brake fluid

Brakes

Guideline

Every 4 years

1 item

Rebuild calipers and master cylinders (seals)

Brakes

Guideline

Every 6 years

1 item

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.