MotoService Log
BSA Round tank 250 (B25)
Example photo: Yesterdays Antique Motorcycles, CC BY-SA 4.0, Wikimedia Commons
BSA · British flat-tank era single (1915-1929)

Round tank 250 (B25)

Library entry covers 1924-1928

9 factory 58 guideline

Published source

B.S.A. 'Some Helpful Hints for Riders of B.S.A. Motor Bicycles', single cylinder models B26 and B26 De Luxe (B.S.A. Cycles Ltd)

Factory owner's handbook. Covers B26 / B26 De Luxe 249cc (c.1926); closest list entry.

Open the source

67 items for a 1924 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
Total-loss (hand pump / drip feed / mechanical pump to waste)
Oil filtration
None (no filter)
Valve gear
Side valve (flathead)
Ignition
Magneto (incl. magdyno, flywheel magneto)
Charging
None (magneto only / no battery charging)
Battery
Wet cell (flooded lead-acid, needs topping up)
Fuel system
Single carburetor
Cooling
Air / oil cooled
Primary drive
Exposed or dry chain (greased)
Gearbox oil
Separate gearbox oil
Clutch control
Hand lever, cable
Final drive
Chain
Front suspension
Girder 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

1924 BSA Round tank 250 (B25)

On the road: every 100 km

1 item
  • Top up total-loss oil tank, check drip feed / pump rate
    Pre-ride / on the road
    Guideline

    Total-loss engines burn their oil by design. Check the sight glass or drip rate and give hand-pump charges as the manual and conditions require.

On the road: every 400 km

1 item
  • Grease girder / springer fork links
    Pre-ride / on the road
    Factory

    Manual: Lubricate front fork link bearings (grease gun). Factory: Text: every 250 mi or weekly.

On the road: every 500 km

3 items
  • Acetylene / oil lamps: check carbide, water and wicks
    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
  • 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 1,000 km

1 item
  • Check chain slack and rear wheel alignment
    Pre-ride / on the road
    Guideline

On the road: every 1,600 km

1 item
  • Check road kit: plugs, points file, master link, tube patches, wire, tape
    Pre-ride / on the road
    Guideline

Every 400 km

2 items
  • Oil steering head
    Front end
    Factory

    Factory: Text: every 250 mi or weekly.

  • Lubricate control cables and lever pivots
    Controls and cables
    Factory

    Manual: Lubricate hubs, gear lever pawl, brake levers, control wires and levers. Factory: Text: every 250 mi or weekly.

Every 800 km

1 item
  • Clean and grease exposed primary chain
    Primary and gearbox
    Guideline

Every 1,600 km or 1 month

2 items
  • Clean drive chain thoroughly (remove and soak, re-lube)
    Final drive
    Factory

    Manual: Remove chains, clean, soak in warm grease and graphite. Factory: Text: every 1,000 mi or monthly.

  • Check wheel bearings for play
    Wheels and tires
    Factory

    Manual: Examine hub adjustment. Factory: Text: every 1,000 mi or monthly.

Every 1,600 km or 6 months

7 items
  • Inspect, clean and gap spark plugs
    Engine
    Guideline
  • Lubricate manual advance / retard control and cable
    Ignition and electrics
    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

Every 1,600 km or 12 months

1 item
  • Grease saddle pivot, check saddle springs / seat post
    Rear suspension and frame
    Guideline

Every 1,600 km

2 items
  • Drain residual oil from crankcase (total-loss)
    Engine
    Factory

    Manual: Drain crankcase oil, recharge with four pumpfuls. Factory: Text: at least every 1,000 mi.

  • Engine shaft cush drive: dismantle, clean, oil
    Engine
    Factory

    Factory: Text.

Every 2,500 km or 6 months

1 item
  • 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.

Every 2,500 km or 12 months

2 items
  • Check and adjust valve clearances
    Engine
    Guideline
  • Adjust clutch free play, lubricate cable and lever pivot
    Primary and gearbox
    Guideline

Every 2,500 km

2 items
  • Decarbonize head, grind / lap valves (top-end decoke)
    Engine
    Factory

    Manual: Decarbonize engine. Factory: Text: after 1,500 mi or so 'it may be necessary'.

  • Change gearbox oil
    Primary and gearbox
    Factory

    Manual: Gearbox: flush with paraffin and refill. Factory: Text: after every 1,500 mi.

Every 3,000 km or 12 months

3 items
  • Inspect hand pump, check valves and drip-feed sight glass
    Engine
    Guideline
  • Check / adjust primary chain
    Primary and gearbox
    Guideline
  • Check girder fork spindle play, adjust friction / hydraulic damper
    Front end
    Guideline

Every 5,000 km or 12 months

12 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
  • Clean and gap contact breaker points, oil cam felt
    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

Every 6,500 km or 12 months

2 items
  • Replace spark plugs
    Engine
    Guideline
  • Lubricate brake cam spindles, check linings and drums
    Brakes
    Guideline

Every 8,000 km 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 9,500 km or 12 months

3 items
  • Clean carburetor float bowl(s), check float level and jets
    Fuel and air
    Guideline

    Ethanol fuel varnishes old carbs quickly in storage.

  • Inspect girder fork links, springs and spindles for wear or cracks
    Front end
    Guideline
  • Lubricate speedometer / tachometer cables, check drive
    Controls and cables
    Guideline

    A dry speedo cable whips the needle and eventually kills the instrument.

Every 9,500 km or 2 years

4 items
  • Check engine breather and oil return
    Engine
    Guideline
  • Lubricate and check automatic advance unit
    Ignition and electrics
    Guideline
  • Magneto: clean slip ring and pickup brush, check HT lead
    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 16,000 km or 2 years

1 item
  • Compression test (or leak-down)
    Engine
    Guideline

Every 16,000 km 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 16,000 km

1 item
  • Replace chain and sprockets (wear based)
    Final drive
    Guideline

Every 19,500 km or 3 years

1 item
  • Replace points and condenser
    Ignition and electrics
    Guideline

Every 24,000 km or 5 years

1 item
  • Inspect clutch plates and springs
    Primary and gearbox
    Guideline

Every 24,000 km

1 item
  • Replace brake linings / skim drums (wear based)
    Brakes
    Guideline

Every 40,000 km or 10 years

1 item
  • Magneto overhaul / re-magnetize, replace capacitor
    Ignition and electrics
    Guideline

    Weak spark when hot is the classic symptom. Old capacitors fail with age, not miles.

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.

Keep up with this schedule on your phone

Add the bike in the app and this chart loads itself, ready to log against and edit.

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Other 1924 BSA models

All 1924 BSA
BSA Model K / H (belt-drive era)
1913-1924
Model K / H (belt-drive era)
Guideline