Harley-Davidson · Harley-Davidson flathead, recirculating (U/UL, W/WL/WLA, G Servi-Car 1937-1973)

G Servi-Car

Library entry covers 1932-1973

68 guideline

Source

No published schedule found yet

These are general intervals for this bike's era and layout, so check them against your workshop manual.

68 items for a 1940 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: Dry sump (separate oil tank)
Oil filtration: None (no filter)
Valve gear: Side valve (flathead)
Ignition: Battery and coil with contact points
Charging: DC generator with regulator
Battery: Wet cell (flooded lead-acid, needs topping up)
Fuel system: Single carburetor
Cooling: Air / oil cooled
Primary drive: Chain fed by engine oil / breather (no separate oil change)
Gearbox oil: Separate gearbox oil
Clutch control: Foot clutch / hand shift
Final drive: Chain
Front suspension: Springer fork
Rear suspension: Rigid (hardtail)
Front brake: Drum (or band / stirrup)
Rear brake: Drum (or band / belt rim)
Wheels: Spoked, tubed
Sidecar: No sidecar

Maintenance schedule

1940 Harley-Davidson G Servi-Car

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

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

2 items

Grease girder / springer fork links

Pre-ride / on the road

Guideline

Grease gun on every nipple until clean grease shows. Touring days add up fast.
Walk-around: check nuts and bolts for vibration loosening

Pre-ride / on the road

Guideline

Old machines shake things loose: exhaust nuts, mudguard stays, footrests, tank mounts, battery strap.

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

Every 1,000 mi or 1 month

1 item

Check battery electrolyte, top up with distilled water

Ignition and electrics

Guideline

Wet-cell batteries on old machines need regular topping up, more in hot weather.

Every 1,000 mi or 6 months

10 items

Change engine oil

Engine

Guideline

Pre-1970 machines: many owners run non-detergent or classic-spec oil with no filter, so short intervals matter. Dry sump: drain the tank and the crankcase/sump, flush the tank and clean the feed and return screens.
Inspect, clean and gap spark plugs

Engine

Guideline
Lubricate manual advance / retard control and cable

Ignition and electrics

Guideline
Adjust foot clutch and hand-shift linkage, lubricate pivots

Primary and gearbox

Guideline
Check gearbox oil level

Primary and gearbox

Guideline
Adjust front drum brake

Brakes

Guideline
Adjust rear drum brake and rod / cable linkage

Brakes

Guideline
Check spoke tension and wheel true

Wheels and tires

Guideline
Inspect tire tread, sidewalls and date codes

Wheels and tires

Guideline
Lubricate control cables and lever pivots

Controls and cables

Guideline

Every 1,000 mi or 12 months

1 item

Grease saddle pivot, check saddle springs / seat post

Rear suspension and frame

Guideline

Every 1,500 mi or 6 months

2 items

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 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 or 12 months

1 item

Check and adjust valve clearances

Engine

Guideline

Every 2,000 mi or 12 months

4 items

Change gearbox oil

Primary and gearbox

Guideline
Check / adjust primary chain

Primary and gearbox

Guideline
Check primary chain oil supply (breather / pump feed)

Primary and gearbox

Guideline

Several pre-war and early post-war designs oil the primary chain from engine oil. Check the feed adjuster or breather path per your year's manual.
Check springer rocker stud play and spring condition

Front end

Guideline

Every 3,000 mi or 12 months

15 items

Check engine mounting bolts and plates

Engine

Guideline
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
Check generator drive belt or chain

Ignition and electrics

Guideline
Clean and gap contact breaker points, oil cam felt

Ignition and electrics

Guideline
Oil / check generator bearings (where an oiler is fitted)

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
Check steering head bearing adjustment

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 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 5,000 mi or 2 years

2 items

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.
Flush oil tank and clean tank screen

Engine

Guideline

Every 6,000 mi or 12 months

4 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
Inspect generator brushes and commutator

Ignition and electrics

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
Lubricate and check automatic advance unit

Ignition and electrics

Guideline
Repack / replace wheel bearings

Wheels and tires

Guideline

Cup-and-cone and taper roller hubs need periodic repacking and adjustment.

Every 8,000 mi or 3 years

1 item

Decarbonize head, grind / lap valves (top-end decoke)

Engine

Guideline

Period practice. Leaded-era valve seats may need hardened seats for unleaded fuel.

Every 10,000 mi or 2 years

1 item

Compression test (or leak-down)

Engine

Guideline

Every 10,000 mi or 3 years

1 item

Repack / replace steering head bearings

Front end

Guideline

Many old machines use loose balls in cups and cones. Taper roller conversions are common.

Every 10,000 mi

1 item

Replace chain and sprockets (wear based)

Final drive

Guideline

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 15,000 mi

1 item

Replace brake linings / skim drums (wear based)

Brakes

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

1 item

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.