The RETROL LD-A1 is a fully functional miniature gasoline engine model inspired by the Lister D Type stationary engine — a single-cylinder workhorse that entered production in 1926 and remained in manufacture until 1964. Over its lifetime more than 250,000 units were produced, powering water pumps, generators, and light machinery on farms and in workshops worldwide.

The LD-A1 faithfully recreates the original's defining features: low-speed four-stroke operation, exposed flywheel and centrifugal governor, evaporative water-cooling hopper, and mechanical CDI ignition — allowing you to see and hear exactly how these classic engines worked.

This model is a 100th anniversary commemorative edition produced in a limited batch of 100 units. It is not affiliated with or endorsed by any original Lister manufacturer.

No. The LD-A1 is a real internal combustion engine that burns actual gasoline, reaches high operating temperatures, and produces carbon monoxide exhaust. It must not be treated as a toy.

• Intended for mechanical model collectors and stationary engine enthusiasts
• Suitable for educational demonstration and display use
• Adults aged 16 and above only

Keep the engine away from children at all times. Maintain a minimum 3-metre spectator clearance during operation.

Yes. The LD-A1 ships Ready to Run (RTR) — fully assembled and factory-tested. No build is required.

• Engine on wooden display base × 1
• Fuel tank × 1 & fuel line × 1
• Drill starter rod × 1
• Accessory pack × 1
• Spark plug (gift) × 1 · Commemorative coin (gift) × 1 · Decals (gift) × 1
• Instruction manual × 1

Not included — required before first use: 1 × AA battery (1.5V), 92# or higher unleaded gasoline, 2T/4T engine oil (10W-40 or 10W-50), distilled water, electric drill.

• Type: Single-cylinder, four-stroke, vertical
• Displacement: 3.6cc · Bore × Stroke: 16.0mm × 18.0mm
• Operating RPM: 500–3,000 rpm
• Cooling: Evaporative water cooling (hopper)
• Ignition: Mechanical trigger CDI, 1.5V AA × 1
• Lubrication: Mixed oil splash — gasoline : oil = 25:1 to 30:1
• Spark plug thread: 3/16–40 imperial
• Dimensions: 208 × 151 × 172mm · Weight: approx. 2,000g
• Materials: Brass, stainless steel, aluminium

Fuel: 92# unleaded gasoline or higher. Zippo lighter fluid works for testing.

Engine oil: 2T or 4T engine oil, grade 10W-40 or 10W-50. Synthetic or conventional both work. The "W" rating only reflects cold-weather viscosity and does not affect normal use.

Mixing ratio: Gasoline to engine oil 25:1 to 30:1. This engine uses splash lubrication — oil is mixed into the fuel, not added to a separate sump. Pre-mix in a clean container before filling the tank.

Cooling water: Distilled water recommended for the hopper. Tap water works but may cause mineral deposits over time.

Do not use nitro fuel, methanol blends, or anything other than clean 92# or higher gasoline. Impurities will block carburetor passages.

The instruction manual states 5–10ml. Use 5ml — not 10ml.

Real owner experience confirms that filling to 10ml causes excess oil to leak from the crankshaft seal, splashing onto the flywheel and the CDI trigger shaft. Reducing to 5ml eliminates flywheel-area leakage in most cases.

This oil is for internal cylinder and valve lubrication only — completely separate from the fuel/oil blend in the fuel tank.

• 1 × AA battery (1.5V) — powers the CDI ignition, installed in the wooden base compartment
• Electric drill (cordless or corded) — the included starter rod fits a standard drill chuck; must rotate clockwise, held level and aligned with the shaft

Manual flywheel starting is also possible but harder — the drill method is much more reliable, especially for new engines.

Outdoors only. The LD-A1 produces carbon monoxide — never run it in a closed garage, indoors, or anywhere without full ventilation.

• Keep fuel away from the running engine and all open flames; do not smoke nearby
• All spectators — especially children — must stay at least 3 metres away
• Wear safety glasses during operation
• Do not touch the cylinder head or exhaust pipe while running or immediately after
• Ensure the spark plug wire and all leads are clear of the rotating flywheel before starting
• Do not place hands near the flywheel or governor pulley while the engine is running

1. Open the wooden base compartment and install 1 × AA battery. Set the ignition switch to ON.
2. Fill the hopper with distilled water and the fuel tank with your pre-mixed gasoline/oil blend.
3. Unscrew the two top oil ports and inject 5ml of engine oil.
4. Open the carburetor throttle to maximum. Block the air inlet with your finger and rotate the flywheel 3–5 turns to draw fuel into the cylinder.
5. Insert the starter rod into the drill chuck, aligned squarely with the starter shaft — drill level, not angled.
6. Spin the flywheel clockwise with the drill. The engine draws fuel automatically — do not press the carburetor primer pin during cranking.
7. Once running, adjust throttle and fuel needle for a stable idle. Keep RPM low for the first several runs during break-in.

If the engine does not fire after several attempts, reset the main carburetor needle to 1.5 turns open and try again before adjusting further.

This is a fuel prime step. Blocking the air inlet while rotating the flywheel creates a rich draw, pulling fuel from the tank through the carburetor into the cylinder before the first fire attempt.

Skipping this on a cold or new engine means the cylinder is dry — the engine will crank without firing. Priming first significantly reduces the attempts needed to start.

No — do not press the primer pin while cranking. Once the flywheel is spinning the engine generates its own intake vacuum and draws fuel automatically. Pressing the pin forces excess fuel into the bowl and can flood the engine.

The primer pin is only useful before cranking: press it once or twice while the engine is completely stationary to pre-fill the carburetor bowl after long storage. Then release and start normally.

If the primer pin feels stuck or will not depress — this is normal on some units. The engine will start without it. Do not force the pin.

The LD-A1 has two starting entry points: the shaft side (oil tank side) and the flywheel side. The starter rod inserts into whichever point you choose, and the drill spins it clockwise to turn the engine over.

Correct use:

• Insert the starter rod fully and squarely — do not start if it feels loose or misaligned
• If the shaft side does not engage on the first attempt, switch immediately to the flywheel side — do not force it
• Hold the drill level and in line with the shaft; any sideways angle puts bending stress on the pin
• Use moderate drill speed only — high torque is not needed and increases pin failure risk
• If the engine feels seized or unusually stiff, stop immediately and investigate before cranking again

The flywheel side is the primary and most reliable starting method. Use the shaft side only if it engages cleanly and without resistance.

Almost always caused by the drill being held at an angle rather than perfectly in line with the starter shaft, creating sideways bending force on the bit.

• Hold the drill straight and level, aligned with the starter shaft axis
• Use moderate speed — high torque settings are unnecessary
• Do not force it if the engine feels seized — stop and investigate first

If your starter rod has broken, contact us with your order number for a replacement.

The starter shaft pin is a deliberate shear pin — designed to break under overtorque to protect the crankshaft. When it snaps, the engine itself is almost always undamaged.

Common causes:

• Repeated forcing from the shaft side when the drive was not engaging cleanly
• Cranking with excessive force while the engine was seized or flooded
• Drill held at an angle, creating sideways stress on the pin

We are aware that the starter pin can break during normal use and treat this as a known issue. Replacement pins are provided free of charge. Contact us with your order number and we will send replacements promptly.

Do not substitute a harder material — the pin must remain softer than the crankshaft. Using a harder pin transfers the failure load to the crankshaft instead.

Yes, manual flywheel starting is possible but requires more speed than most people expect. The LD-A1 uses metal piston rings and needs a fairly fast spin to build enough compression to fire.

An electric drill provides consistent speed and torque that is difficult to match by hand, especially on a cold or new engine. As the engine breaks in over the first several hours of use, starting effort gradually reduces.

Normal stop: Close the throttle completely, then turn the ignition switch to OFF.

Emergency stop: Pinch the fuel line between the tank and carburetor to cut fuel immediately.

Never grab the flywheel or starter pulley to stop the engine while it is rotating. Always turn the ignition switch off when the engine stops running.

• Main fuel needle: open 1.5 turns from fully closed
• Auxiliary needle: protruding approximately 1.5mm above the flat surface

These cover most conditions but may need minor adjustment based on altitude, temperature, and fuel type. Always reset to these positions as a baseline before attempting further tuning.

Clockwise on the main needle = leaner mixture. Counterclockwise = richer. Adjust in 15° increments and listen to the exhaust after each change.

Running rich (too much fuel): heavy exhaust smoke, sluggish acceleration, engine bogs or feels wet, stalls under load.
Fix: turn main needle clockwise in 15° steps.

Running lean (too little fuel): sharp metallic exhaust note, rapid temperature rise, stalls immediately after accelerating.
Fix: turn main needle counterclockwise in 15° steps.

Correct condition: exhaust sound is soft and consistent, faint oil mist at the exhaust tip, smooth power through the RPM range.

Use the throttle stop screw on the carburetor: clockwise increases idle; counterclockwise decreases idle.

Set idle just high enough for the engine to run steadily without stalling. At correct idle the flywheel turns at a slow, even pace with no misfires or hunting.

1. Check ignition spark. Switch CDI on, remove the spark plug, reconnect its wire, rest the plug base on the engine body (ground), and spin the flywheel. You should see a strong blue spark. A spark that fades after a few turns usually means a low battery.
2. Replace the AA battery if spark is weak or absent.
3. Check the CDI unit. If a new battery does not restore spark, the CDI may be faulty. Contact us — we can arrange a replacement.
4. Check fuel delivery. Open throttle fully, block the air inlet, spin the flywheel several turns. You should smell fuel at the plug hole. No fuel smell → check the fuel line connection and tank level.
5. Reset carburetor needles to factory position (main: 1.5 turns, auxiliary: 1.5mm above surface) and retry.
6. Check compression. Thumb over the spark plug hole, spin flywheel — you should feel strong resistance. Weak compression → contact support.

Do not force-start a flooded engine. Cranking with excess fuel in the cylinder can bend the connecting rod or damage the crankshaft — not covered by warranty.

1. Remove the spark plug.
2. Close the fuel needle fully.
3. Cover the plug hole with a cloth, then briefly crank the engine to expel excess fuel.
4. Dry or replace the spark plug.
5. Refit the plug, reopen the main needle to 1.5 turns, and start normally.

Crankshaft damage most commonly results from:

• Force-starting a flooded engine — excess liquid causes hydraulic lock; cranking through it bends the connecting rod or cracks the crankshaft
• Repeated heavy-torque cranking from the shaft side when the drive was not engaging
• Cranking with a misaligned drill — lateral force is transmitted through the drive pin to the crankshaft

Signs of damage:

• Starter drive spins freely without turning the engine
• Unusual knocking or grinding during cranking or running
• Engine compression suddenly absent after a hard crank attempt
• New oil leak at the crankshaft seal that was not present before

If you suspect crankshaft damage, stop operating immediately and contact us. Continuing to run a damaged crankshaft causes further secondary damage.

Crankshaft damage caused by force-starting a flooded engine or incorrect drill use is not covered under warranty.

In most cases, overfilling is the cause. Reduce your oil level to 5ml and check again before concluding there is a seal problem.

• Auxiliary starter shaft (under the fuel tank): Oil inside the crankcase splashes onto this shaft during operation — this is splash lubrication reaching the shaft, not a seal failure. Keeping oil at 5ml eliminates this in most cases.
• CDI trigger/ignition drive shaft: This shaft has a seal. A light oil film is normal. Active dripping that persists after reducing to 5ml is not normal — contact support.

The vast majority of reported leaks at these locations stop once oil is reduced from 10ml to 5ml. Confirm this before contacting support.

No screw is missing. The hole on the governor side of the engine casing is a decorative feature — it does not pass through the wall and has no structural or sealing function.

Verify this yourself: shine a small torch into the hole and you will see it is a blind (non-through) hole. Photos online showing a screw in this position are from different engine variants, not the LD-A1.

The LD-A1 includes several features that look unusual to new owners but are correct by design:

• Governor side hole: Decorative blind hole — no screw required (see FAQ above)
• Crankcase vent openings: Small openings are normal breather vents — air exiting during operation is expected
• Decorative components: Some parts noted in the manual as "decorative (do not require lubrication)" have no mechanical function — they are part of the authentic Lister D aesthetic
• Speed control linkage and governor spring: These visible, exposed components are intentional — not unfinished or broken

If after checking against the manual and this FAQ you still believe something is genuinely absent, contact us with a photo and we will confirm quickly.

No fuel delivery: The needle valve inside the carburetor may be fully closed or blocked. Check the fuel line is connected and unkinked and the tank vent is open. Clean the carburetor inlet if blocked.

Fuel blowback from intake: Indicates incorrect valve timing, a valve not seating properly, or valve clearance too tight (correct clearance: 0.1mm). Contact support before attempting valve adjustment.

• Cooling water: confirm the hopper has sufficient distilled water
• Fuel mixture: lean mixture causes rapid overheating — richen the main needle slightly
• Head gasket: thinner-than-stock gaskets raise compression and heat — revert to original
• Break-in: new engines run warmer; keep RPM low for the first several hours

• Carburetor needle off — reset to factory as first step
• Air leak at intake manifold or crankcase ventilation — inspect all joints and gaskets
• Insufficient cylinder compression — causes hunting at idle
• Incorrect valve timing — contact support before adjusting

This is an orientation issue, not a defect. The hopper lid cover can be mounted two ways. Remove the six screws with a 1.5mm screwdriver, rotate the cover 180°, and refit.

Replace if you notice any of the following:

• Electrode surface rough and whitish
• Electrode tip bent or deformed
• Carbon deposits or corrosion on the plug body
• Engine loses power at idle, or starts then stalls shortly after

Replacement spec: 3/16–40 imperial thread spark plug. Do not fit metric plugs — the thread will not match.

• Remove dirt from inlet passages using a soft brush and compressed air
• Inspect the air filter after every hour of operation; replace if contaminated. When removing, avoid knocking debris into the carburetor opening
• Use clean, filtered fuel to reduce deposit build-up

Do not use corrosive solvents — they damage the rubber O-rings inside the carburetor.

Do not remove the timing belt. Removing it risks disturbing valve timing, which is difficult to restore without specialist tools.

To clean in place: wipe with isopropyl alcohol (IPA). Do not use petroleum-based solvents — they degrade belt material.

1. Empty the fuel tank at the end of each session.
2. Switch ignition on and restart — let the engine run until it stalls from fuel starvation, burning off residual fuel in the carburetor and cylinder.
3. Inject a small amount of anti-corrosion oil into the lubrication ports, then briefly run the engine to distribute it.
4. Apply a small amount of solid lubricant (grease or moly paste) to the camshaft and valve tappets.
5. Turn off the ignition switch. Store in a dry location away from direct sunlight.

Do not inject anti-corrosion oil into the carburetor — it will degrade the O-rings inside.

For most owners, full disassembly is unnecessary and not recommended. If a problem cannot be resolved through carburetor adjustment and spark plug replacement, contact our support team before opening the engine. Unauthorised disassembly that causes further damage may affect your after-sales coverage.

• Spark plug thread: 3/16–40 imperial (not metric)
• Engine oil grade: 10W-40 or 10W-50, 2T or 4T
• Fuel/oil mix ratio: 25:1 to 30:1 (gasoline to oil by volume)
• Top lubrication oil fill: 5ml (do not exceed)
• Valve clearance: 0.1mm
• Base mounting bolts: M2.5 × 14mm
• Hex screwdriver for base & hopper screws: 1.5mm Allen key
• CDI battery: 1 × AA, 1.5V
• Drill rotation: clockwise only
• Timing belt cleaning: isopropyl alcohol (IPA) only — do not remove the belt

The standard base bolts (M2.5 × 14mm) may be shorter than some cart/trolley kits require. Source longer M2.5 bolts from a local hardware store. Contact us if you need guidance on the correct length for your specific cart.

The current production LD-A1 uses a mixed-material crankcase: brass for internal components and aluminium for the main housing and cover. A full solid-brass crankcase is not available as standard — the cost makes it prohibitively expensive for most customers.

For custom material enquiries, contact us to discuss what is currently feasible.

Yes. Individual spare parts are available, including:

• Spark plugs (3/16–40 imperial thread)
• Starter shaft pins & drill starter rods
• CDI ignition units
• Centrifugal governor components
• Flywheels and flywheel fixing screws
• Fuel lines and fittings · O-rings and gaskets

Contact us with your order number and a description or photo of the part needed.

Yes. We support wholesale and distributor enquiries for the LD-A1 and our wider product range. Contact us with your estimated quantities, target market, and relevant business information. Our team will respond with pricing and terms.

Inspect the package carefully in front of the delivery person before signing. If you find shipping damage:

• Document it with photos immediately
• Note the damage with the logistics company on the spot, or reject delivery if damage is severe
• Send photos via our contact page within 24 hours of receipt

Claims raised after 24 hours cannot be attributed to shipping damage. Act promptly.

If the engine fails to perform as described, contact us within 3 days of receiving your order. If the issue is verified by our team or a recognised third party, we will provide free repair or replacement of the relevant parts.

Please work through this FAQ and the troubleshooting section fully before contacting support — the large majority of startup issues are resolved through carburetor needle adjustment or spark plug inspection.

• Damage from unauthorised disassembly or modification
• Damage from drops, impacts, or water ingress
• Normal consumables: spark plugs, fuel lines, O-rings, starter pins
• Incorrect fuel type or oil ratio
• Connecting rod / crankshaft damage from force-starting a flooded engine
• Crankshaft damage from improper or excessive-force starting
• Paint or cosmetic issues from impacts or improper handling

For out-of-warranty repairs we can still assist — parts and labour costs apply, and the customer covers shipping.

Visit our contact page or email service@stirlingkit.com

Please include your order number, a clear description of the issue, and photos or a short video where possible.