Suzuki GT380 / GT550 Sebring / Indy — Example photo: Motacilla, CC BY 4.0, Wikimedia Commons

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Suzuki · Suzuki two-stroke twin / triple (T20-T500, GT 1965-1977)

GT380 / GT550 Sebring / Indy

Library entry covers 1972-1977

22 factory 46 guideline

Published source

Suzuki GT380 Service Manual (Suzuki Motor Co.), Periodical Inspection List

Factory service manual. Covers GT380 service manual (1972-), chart in km and mi; GT550 shares the CCI triple layout.

68 items for a 1972 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 oil injection (Autolube, Injectolube, Pilgrim pump...)
Oil filtration: None (no filter)
Valve gear: None (two-stroke porting)
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: Separate gearbox oil
Clutch control: Hand lever, cable
Final drive: Chain
Front suspension: Telescopic fork
Rear suspension: Swingarm, twin shocks
Front brake: Drum (or band / stirrup)
Rear brake: Drum (or band / belt rim)
Wheels: Spoked, tubed
Sidecar: No sidecar

Maintenance schedule

1972 Suzuki GT380 / GT550 Sebring / Indy

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 600 mi

1 item

Check chain slack and rear wheel alignment

Pre-ride / on the road

Guideline

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 4,000 mi

1 item

Walk-around: check nuts and bolts for vibration loosening

Pre-ride / on the road

Factory

Manual: Bolts, nuts and spokes: retighten. Factory: Periodical inspection list p.54: first at 750 mi

Every 1,000 mi or 6 months

2 items

Check gearbox oil level

Primary and gearbox

Guideline
Adjust rear drum brake and rod / cable linkage

Brakes

Guideline

Every 2,000 mi or 12 months

1 item

Grease swingarm pivot

Rear suspension and frame

Guideline

Every 2,000 mi

14 items

Check / bleed / adjust oil injection pump cable

Engine

Factory

Manual: Oil pump: check operation, adjust control lever marks. Factory: Periodical inspection list p.54: first at 750 mi (1,000 km)
Check cylinder head bolt torque

Engine

Factory

Manual: Cylinder and cylinder head nuts: retighten. Factory: Periodical inspection list p.54: first at 750 mi; exhaust pipe clamp nuts retightened at the same intervals
Inspect, clean and gap spark plugs

Engine

Factory

Manual: Spark plugs: clean and adjust gap. Factory: Periodical inspection list p.54: first clean at 750 mi
Muffler: retighten exhaust pipe clamp fitting nuts

Engine

Factory

Factory: Periodical inspection list (ManualsLib viewer p.54, re-read from the page image): at 1,000 km (750 mi) and every 3,000 km (2,000 mi)
Check throttle cable(s) free play and return

Fuel and air

Factory

Manual: Throttle, clutch and brake cables: adjust play. Factory: Periodical inspection list p.54: first at 750 mi
Clean / inspect air filter

Fuel and air

Factory

Manual: Air cleaner: clean. Factory: Periodical inspection list p.54
Synchronize carburetors

Fuel and air

Factory

Manual: Carburetors: adjust throttle valve screw and pilot air screw. Factory: Periodical inspection list p.54: first at 750 mi
Check battery electrolyte, top up with distilled water

Ignition and electrics

Factory

Manual: Battery: check and service electrolyte. Factory: Periodical inspection list p.54: first at 750 mi
Clean and gap contact breaker points, oil cam felt

Ignition and electrics

Factory

Manual: Contact points: check gap and ignition timing, lubricate cam felt. Factory: Periodical inspection list p.54: first at 750 mi
Adjust clutch free play, lubricate cable and lever pivot

Primary and gearbox

Factory

Manual: Clutch: adjust. Factory: Periodical inspection list p.54: first at 750 mi
Change gearbox oil

Primary and gearbox

Factory

Manual: Gearbox oil: change. Factory: Periodical inspection list p.54: first at 750 mi
Clean drive chain thoroughly (remove and soak, re-lube)

Final drive

Factory

Manual: Drive chain: wash, adjust and lubricate. Factory: Periodical inspection list p.54: chain section p.49 says every 500 mi (800 km); chart also lists it at 4,000 mi
Adjust front drum brake

Brakes

Factory

Manual: Brakes: adjust play. Factory: Periodical inspection list p.54: first at 750 mi
Inspect tire tread, sidewalls and date codes

Wheels and tires

Factory

Manual: Tires: check tread condition. Factory: Periodical inspection list p.54

Every 3,000 mi or 12 months

11 items

Check engine mounting bolts and plates

Engine

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
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 spoke tension and wheel true

Wheels and tires

Guideline
Check wheel bearings for play

Wheels and tires

Guideline

Every 4,000 mi or 12 months

2 items

Replace spark plugs

Engine

Guideline
Lubricate brake cam spindles, check linings and drums

Brakes

Guideline

Every 4,000 mi

5 items

Decarbonize exhaust ports, pipes and baffles

Engine

Factory

Manual: Cylinder head, cylinder and muffler: remove carbon. Factory: Periodical inspection list p.54
Replace spark plugs (two-stroke)

Engine

Factory

Manual: Spark plugs: replace. Factory: Periodical inspection list p.54
Clean fuel tap filter / sediment bowl

Fuel and air

Factory

Manual: Fuel cock: clean fuel strainer. Factory: Periodical inspection list p.54: first at 750 mi
Check steering head bearing adjustment

Front end

Factory

Manual: Steering stem: check play, retighten stem nut. Factory: Periodical inspection list p.54: first at 750 mi
Lubricate control cables and lever pivots

Controls and cables

Factory

Manual: Throttle, clutch and brake cables: lubricate; grease throttle grip. Factory: Periodical inspection list p.54

Every 6,000 mi or 12 months

4 items

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

1 item

Lubricate and check automatic advance unit

Ignition and electrics

Guideline

Every 8,000 mi

2 items

Clean carburetor float bowl(s), check float level and jets

Fuel and air

Factory

Manual: Carburetors: overhaul and clean. Factory: Periodical inspection list p.54
Replace points and condenser

Ignition and electrics

Factory

Manual: Contact points: replace. Factory: Periodical inspection list p.54

Every 10,000 mi or 2 years

2 items

Compression test (or leak-down)

Engine

Guideline
Change fork oil

Front end

Guideline

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

Every 10,000 mi

1 item

Replace chain and sprockets (wear based)

Final drive

Guideline

Every 12,000 mi or 2 years

1 item

Replace air filter element

Fuel and air

Guideline

Every 15,000 mi or 5 years

1 item

Inspect clutch plates and springs

Primary and gearbox

Guideline

Every 15,000 mi

1 item

Replace brake linings / skim drums (wear based)

Brakes

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 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

3 items

Inspect fuel tank for rust, sealer failure, leaks

Fuel and air

Guideline
Inspect wiring, bullet connectors and ground points

Ignition and electrics

Guideline
Inspect frame, welds and lugs for cracks

Rear suspension and frame

Guideline

Every 4 years

2 items

Replace oil injection delivery lines

Engine

Guideline
Replace fuel lines

Fuel and air

Guideline

Old rubber and modern ethanol fuel do not mix well.

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.