Thank you for choosing Stirlingkit and for your continued support. Below is a user guide to the most common questions about the RETROL G16 horizontal mill engine: how to set it up, how to start it with the drill starter adapter, and what to do if something doesn't go as expected. Like any real running engine, the G16 enjoys a little setup and the occasional fine-tune, and most of it takes just a few minutes at your workbench.
1. What's in the RETROL G16 Box and What to Prepare
| In the box | Not included (please prepare) |
|---|---|
| Engine (ready to run) Fuel tank and fuel line CDI igniter Electric drill starter adapter USB power cable / clip lead Instruction manual |
92 octane (RON) or higher gasoline – regular unleaded in the US 2-stroke (2T) engine oil 6–10V battery pack Cordless drill with a speed trigger Water or coolant for the cooling system |
RETROL G16 key specifications
Full product details are on the RETROL G16 Horizontal Mill Engine page.
| Type | Horizontal 4-stroke, water-cooled gasoline engine |
| Bore × stroke | 22 mm × 24 mm |
| Flywheel | Cast iron, 225 mm diameter × 20 mm |
| Ignition | CDI, 6–10V supply |
| Spark plug | 1/4-32 thread ME8 |
| Lubrication | Oil cup on the cylinder + oil mixed into the fuel |
| Cooling | Plunger-type water pump |
2. Before the First Run: Fuel, Oil and Cooling
Mix fuel for the G16
Mix 2T oil into the gasoline at 1 part oil to 50 parts gasoline (about 20 ml of oil per litre of fuel). The oil in the fuel keeps the inside of the engine lubricated.
Lubricate
- Put a few drops of 2T oil on the connecting rod bearings and any exposed moving joints.
- Fill the oil cup on top of the cylinder with a small amount of 2T oil. This feeds the cylinder directly while the engine runs.
- A drop of oil on the back of the piston before each run keeps the piston rings happy, especially on longer runs.
Fill the cooling system
Fill the water tank with clean water or coolant. Coolant helps the pump's check valves stay clean and rust-free.
Turn it over by hand
Turn the flywheel slowly by hand through a few full turns. It should move smoothly and quietly. If you hear a light clicking from the valve gear, a quick gear clearance adjustment will take care of it.
Connect the G16 CDI ignition
- Connect the CDI to a 6–10V battery: red to positive (+), black to negative (–). It's worth a quick double-check before switching on.
- Fix the black ground wire to the bottom of the engine with the screw provided and tighten it.
- Alternatively, power the CDI with the USB cable from a power bank or adapter.
3. How to Start the G16 with the Drill Starter Adapter
- Prime the fuel line. Open the fuel needle counterclockwise, turn the flywheel by hand until fuel reaches the end of the fuel line, then close the needle clockwise.
- Fit the adapter. Clamp the smooth end of the adapter in your drill chuck and engage the cross pin with the crankshaft.
- Set the drill. Choose the low-speed setting, turning the engine in its normal running direction.
- Spin and adjust. Run the drill in short bursts with your right hand while slowly opening the fuel needle counterclockwise with your left hand.
- Pull away when it fires. As soon as the engine catches, release the trigger and take the drill away.
- Fine-tune. Adjust the fuel needle until the engine settles into a smooth, steady run.
Watch it in action: the video below starts at the drill-starting part (4:42).
Prefer a quick look? Here's a short clip:
G16 smoke rings
One of the G16's party tricks is blowing smoke rings from its chimney. They form best at around 800–1,000 RPM, so try running the engine a little slower once it's warmed up.
For thicker, more visible rings, add a small amount of diesel to your fuel: about 1 part diesel to 50–60 parts gasoline (roughly 15–20 ml of diesel per litre of fuel), on top of the usual 2T oil.
4. Simple Adjustments: Gear Clearance, Timing and Cooling
The adjustments below are part of normal setup and maintenance, and they won't affect your warranty. If you'd rather not do them yourself, send us a short video and our team will walk you through it.
G16 gear clearance adjustment
If the valve rocker arm makes a light clicking sound, the gap between the crankshaft gear and the camshaft gear just needs closing up a little. The camshaft is designed to be adjusted up and down for exactly this.
- Loosen the two adjusting screws shown above slightly.
- Move the camshaft so the two gears mesh a little more closely. They should turn freely with just a very small amount of play.
- Tighten the screws and turn the flywheel by hand through a few full turns. It should be smooth and quiet.
If the flywheel feels slightly stiff at one point, ease the adjustment back a touch.
G16 cam adjustment
The cams are set at the factory and normally don't need touching. You'd only reset them if the valve timing has been disturbed, for example after taking the engine apart.
G16 ignition timing
The spark should fire near the end of the compression stroke, as the piston approaches top dead center.
G16 cooling pump check valves
If water flow slows down, the small steel ball in one of the check valves may be sticking. Tap the check valve gently with a wooden stick to free it. If that doesn't do the trick, remove the valve, clean it, and refit it in the same direction (the valves fit from right to left).
5. If Something Isn't Right: G16 Quick Fixes
Most G16 engines run happily out of the box. If yours needs a little help, find what you're seeing below. These are the same checks our support team walks through, and most take only a few minutes.
If your RETROL G16 has no spark at the plug
To check the RETROL G16 for spark, pull the plug lead off, fit the spark plug into the lead, rest the plug's metal body on the engine, and turn the flywheel. If there's no spark, go through these in order:
- Battery: fit a fresh battery that gives 6–10V.
- Wiring: red to positive, black to negative, and the black ground wire screwed firmly to the engine.
-
Quick CDI test: unplug the Hall sensor connector. With the CDI powered, briefly touch the red and white wires of the Hall connector together, just for a moment.
- If you see a spark: the CDI is working, and you just need a new Hall sensor.
- If there's still no spark: the CDI unit needs replacing. Contact us and we'll help you get the right part.
If the G16 has a spark but doesn't fire
- If the plug is wet with fuel: the cylinder has taken in a little too much fuel. Unplug the spark plug lead, turn the flywheel backwards a few turns, then remove the plug, wipe it dry and refit it. Start again with the fuel needle opened a little less.
- If the plug is dry: check the fuel line is primed and the fuel needle is open.
- If the flywheel turns very easily with little resistance: compression may be low. See the next item.
If G16 compression feels low
Low compression on the G16 is usually a little carbon or debris keeping a valve from sealing fully. Turn the flywheel until the piston is just before top dead center, then give the valve a few quick, light taps with a small wooden mallet to help it seat. If compression doesn't come back, send us a short video and we'll advise on the next step.
If the G16 valve rocker arm clicks
The G16 gear clearance just needs a small adjustment. Follow G16 gear clearance adjustment and the clicking should go away.
If your G16 makes a new knocking or grinding sound
Stop the G16 and turn the flywheel by hand to see whether it moves smoothly. Then send us a short video and a photo of the gears, and our team will help you work out what needs attention before you run it again.
If the G16 slows down once it's warm
The G16 piston would like a bit more oil. Let the engine cool, check the oil cup is topped up and your fuel has oil mixed in, and add a few drops of 2T oil to the back of the piston before the next run.
If the G16 cooling water stops flowing
One of the G16 pump check valves is probably sticking. See G16 cooling pump check valves.
If the G16 flywheel shows surface rust
Surface rust on the G16 flywheel is cosmetic and doesn't affect how the engine runs. Wipe it off with a clean cloth, then apply a thin film of oil to protect it.
If the G16 fuel hose is lost or worn
The G16 uses a small fuel hose. Any fuel-resistant hose with a 3 mm inner diameter and 5 mm outer diameter will fit.
6. Care and Storage
- After each run: wipe off fuel and oil, and give the flywheel and bare metal parts a wipe with a lightly oiled cloth.
- Cooling system: drain the water if the engine will sit for more than a few days, or use coolant.
- Fuel: empty the fuel tank before storage.
- Storage: keep the engine somewhere dry, with a cover to keep dust off.
7. G16 Replacement Parts and Upgrades
Replacement parts and upgrades for the G16, including the CDI igniter, Hall sensor, welded steel gear set, oil cup, spark plug and drill starter adapter, are available on the RETROL G16 Engine Parts page.
- Manual hand crank: discontinued by the manufacturer.
- Flywheel: not sold as a separate part.
- Small fuel hose: not sold by us, but any fuel-resistant hose with a 3 mm inner diameter and 5 mm outer diameter will fit.
8. RETROL G16 FAQ
Does the RETROL G16 come with a hand crank?
RETROL G16 orders placed before February 2026 included a hand crank. From February 2026 onward, the G16 comes with an electric drill starter adapter instead. The hand crank is no longer available as a separate part.
What fuel and oil does the G16 use?
The RETROL G16 runs on 92 octane (RON) or higher gasoline, regular unleaded in the US, mixed with 2-stroke (2T) oil at 1:50. Keep the oil cup on the cylinder topped up with 2T oil as well.
What battery and spark plug does the RETROL G16 need?
The G16 CDI igniter runs on a 6–10V battery, or on USB power with the included cable. The G16 spark plug is a 1/4-32 thread ME8.
What should I check if my RETROL G16 doesn't start right away?
Start with the simple things on your G16: a fresh battery, correct wiring, fuel reaching the carburetor, and a dry spark plug. Quick fixes walks through each one.
How do I make the RETROL G16 blow smoke rings?
Run the G16 at around 800–1,000 RPM. For thicker rings, add about 1 part diesel to 50–60 parts gasoline in the fuel.
Have a better way to start it? 💨
A smoother drill-start technique, your go-to needle setting for smoke rings, a neat way to keep the flywheel shining: if it worked on your RETROL G16, other owners want to know. Send it in and we'll add the best tips to this guide under your name.
🎁 If we feature your tip, we'll send you a thank-you gift from Stirlingkit.
Email service@stirlingkit.com or join our Engine Tips Challenge.
More About the RETROL G16
- A Closer Look at the New and Old RETROL EngineHow the red G16 differs from the original green version, with 11 upgrades explained.
- Explore All RETROL EnginesSee the full RETROL range of stationary and hit-and-miss engine models.
0 commenti