Q&A: How to Fix the Problems of M90?

Q1: We are having a problem starting our M90. There is no spark from the spark plug. We have tried it with 2 batteries still nothing. The switch is in the on position. it has compression no spark. What do we need to do next?

A1:

1. Please try again with 3 1.5V batteries;
2. Check the solder joints of the battery box to see if the contact is bad. If it still doesn't work, the igniter may be broken;
3. If the igniter is broken, you need to replace the igniter

If there is no compression, there should be foreign matter entering the engine, which prevents the valve from closing normally. There are three ways to try to solve it.
1. Put a few drops of lubricating oil on the carburetor. Use an electric drill to drive the engine for a while. Under the action of the lubricating oil, the foreign matter is discharged to restore the cylinder pressure.

2. Use an electric drill to rotate the hour hand (the opposite direction of the engine's working direction) to rotate the engine for a while. Discharge the foreign matter by turning the rotation.

3. Remove the cylinder head. Foreign matter on the valve may cause the valve to not close properly. Check the foreign matter on the valve and restore the cylinder pressure after cleaning.

How TO Solve?
The engine needs a new battery to make sure it has enough voltage for the igniter to work properly.

When adding fuel from the fuel tank. But there will be air in the fuel tank. You need to press the carburetor port by hand. Rotate the flywheel. The piston allows the engine to suck fuel into the carburetor.

The engine has been adjusted for work (using gasoline) before shipment, but the setting of the carburetor may need to be fine-tuned under different fuels. You can fine-tune the size of the main oil needle.

Lubrication method: Lubricating oil of no more than 4ML can be added to the crankcase to ensure splash lubrication of the crankshaft.

fuel and dosage: The fuel tank capacity is about 15ML. The engine can use 95# gasoline or aviation kerosene. The engine needs to add 4% lubricating oil to the fuel.