OKMO Lister D Engine FAQs | EngineDIY

If you own or recently purchased the OKMO Lister D engine, you may encounter various operational, lubrication and assembly issues during use. We have sorted out the most frequently asked questions from our customers, along with professional answers and practical tips in this complete Q&A guide. This post covers oil selection, startup problems, oil leakage, component failure, air leakage and other common troubles, helping you solve issues quickly and keep your Lister D engine running stably.

Frequently Asked Questions (Q&A)

🛢️ Q1: Which engine oil is suitable for OKMO Lister D? Can I mix synthetic oil with gasoline?

Question Details:
The official suggested oil is 10W-50 4T. I only found Castrol synthetic oil in this specification, and also got regular Castrol 10W-30 4T oil. Are both oils compatible? Besides, if synthetic oil is recommended, do I need to mix it with gasoline?

Answer:

We use 10W-50 4T synthetic oil for the Lister D engine, and oil-gas mixing is NOT required for this model.

Apart from 10W-50 4T, 10W-40 4T oil is also fully applicable. The letter "W" in oil grade stands for Winter. Both the 10W-30 4T conventional oil and 10W-50 4T synthetic oil you found work for the engine.

🔛 Q2: Engine fails to start manually but works well with an electric drill. Can I adjust the valve clearance?

Question Details:

My Lister D engine runs normally once started. However, it cannot be started manually, while an electric drill can start it easily. I suspect the compression is a bit low. Will this situation improve after running the engine for a while? 

Answer:

This engine is equipped with metal piston rings, which require a relatively high rotating speed to complete manual startup, so manual cranking difficulty is a normal phenomenon.
As for the valve clearance: This model is fitted with a movable carburetor choke. Once you adjust the valve clearance improperly, it will be hard to restore to the original state. We do not recommend adjusting the valve clearance arbitrarily.

🚿 Q3: Minor oil leakage at both sides of the cylinder head bottom

Question Details:

There is slight oil leakage on the bottom two sides of the cylinder head. The leakage volume is small, but this situation should not happen. How to fix it?

Answer:

The most common cause is overfilling engine oil. The standard oil filling volume for this engine is 5ml. As long as you add oil within the standard dosage, oil leakage at the cylinder head will not occur. Please check and adjust the oil level first.

⚙️ Q4: Starter pawl slips and cannot drive the engine

Question Details:

The starter pawl on the fuel tank side is separated from the shaft and idles in place, so it cannot drive the engine to run. I fixed the starter shaft and rotated the flywheel, and I guess the pin passing through the starter pawl is broken.

Answer:

First check if the flywheel is fully locked. There is a fastening screw inside the flywheel. Crankshaft slippage only happens under extreme heavy pressure.

We suggest starting the engine from the large flywheel side. Its gear ratio is 1:2, which provides better meshing effect and more stable power transmission.

💨 Q5: Exhaust valve suspected air leakage during compression stroke

Question Details:

During the compression stroke, the exhaust valve should be fully closed. When I turn the engine back and forth and listen closely to the exhaust port, I can hear obvious blowing sounds. I think the exhaust valve leaks air, which makes the engine unable to work normally.

Answer:

The airflow sound from the exhaust port is normal. The Lister D engine is designed with a crankshaft exhaust hole, and air discharge during operation is an inherent working state, not exhaust valve leakage.

💭 Q6: Air leaks from carburetor mixture screw threads and throttle shaft

Question Details:

I found air entering from the threads of the mixture screw and the throttle shaft of the carburetor, which looks like vacuum leakage. Is this a malfunction?

Answer:

This is a normal structural design, not a fault. If you keep turning the flywheel continuously without starting the engine, excess fuel will overflow from the intake valve. This reserved air passage can prevent fuel from flooding into the cylinder in large quantities, which protects the engine’s internal structure.

📝Final Notes

This Q&A will be updated continuously. If you encounter other problems while using the OKMO Lister D engine, feel free to leave us a message. We will reply with professional solutions as soon as possible.

💡 Maintenance Tip: Always follow the standard operation and lubrication rules to extend the service life of your Lister D engine.