Servicing small 2-stroke engines

Useful Servicing Tips for Better 2-Stroke Engine Performance on Hand-Held Machines

Correct Oil Usage >>


Correct Gasoline Usage >>

4 Steps to Starting a 2-Stroke Engine >>

4 Steps of Operational Service on a 2-Stroke Engine >> 

7 Steps of Periodic Engine Maintenance on a 2-Stroke Engine >>

Before any service and repair always remove the spark plug from engine or the HT wire from the spark plug.

Correct Oil Usage 

Use only high-performance ISO-EG’D’ or JASO- F’D’ or better quality rating two-stroke oil suited for Air Cooled engines. Lesser grade two stroke-oil can permanently damage the engine. Only use the appropriate warranty certified manufacturers recommended oil – ie. Stihl oil for Stihl machines, Echo oil for Echo machines.  

Correct Gasoline Usage 
Use CLEAN, FRESH, lead-free gasoline. Always place the correct quantity of 2-stroke oil into the separate fuel can to help mix oil/fuel prior to filling with gasoline. If you intend to keep your fuel mix for longer than five weeks, you can add a ‘fuel stabilizer’ to your separate fuel can at fill-up time – this will help extend the fuel life. Please Note: Do not use gasoline containing more than 10% alcohol/ethanol, as it will most likely damage your engine. 
 Clean and evaporate off any spilled fuel to eliminate any spontaneous combustion.

4 Steps to Starting a 2-Stroke Engine

Familiarise yourself with the controls as described in the operators manual.

1. Primer 
If the engine is equipped with a Primer make sure the engine is properly primed (see Operators Manual). Most 2-strokes require 4 to 6 pumps from cold. 

2. Choke
Most engines are equipped with a choke. Make sure the choke plate is fully CLOSED. Check for the choke closed symbol next to the lever/knob.

3. Throttle Lock 
Lock the high speed Throttle Lock. 

4. Starter Handle
Pull rapidly on the starter handle until the engine ‘POPs’ (3 to 4 pulls max).
Move the choke to ‘OFF’. Now attempt to re-start the machine pulling briskly on the starter handle. The engine should fire up to full operating speed. Now click the Throttle Lock OFF. The machine will now idle ready for use. If it doesn’t start, repeat process 1-4.

 With Hand-Held machines, always hold the machine firmly on the ground. More than 3 or 4 pulls while on choke can ‘flood’ the engine preventing it from starting.

4 Steps of Operational Service on a 2-Stroke Engine 
Always place your machine on a bench for easy periodic maintenance. Remove the spark plug lead. Read your operators manual for item description and maintenance pointers. The main items to check are:

1. Air Filter for cleanliness 

2. Spark Plug for damage, wear and coking up.

3. HT spark plug lead for cracks and wear.

4. Check and tighten all screws and bolts, replace any missing.
Now re-start and check for a smooth crisp engine sound.

7 Steps of Periodic Engine Maintenance on a 2-Stroke Engine
Remove the spark plug lead. Read your operators manual for item description and maintenance pointers.

1. Air Filter 
Remove, clean or if really dirty, replace here.

2. Spark Plug 
Remove and replace. Check all HT leads for wear, splitting or cracking. If in doubt, have a professional service person check this area.  

3. Screws, Nuts and Bolts 
Check and tighten all external screws, nuts and bolts. Replace any missing. 

4. Carburettor 
Unless you have been specially trained in this area this complicated item is best left to the professionals. Reset the ‘jets’ in accordance to the operators manual.

5. Fuel Tank 
Clean the fuel tank out of water and debris as best as you can. Hooking the fuel filter out for checking or replacing with a piece of hooked shaped wire may solve engine starvation, the filter may be blocked. Check the fuel lines for perishing, cracks or splitting. Fuel lines can go hard under the fuel. A quick squeeze for softness will indicate this. Replace all suspect fuel lines. 

6. Exhaust 
No power with the engine going? Hold your hand about 10cm from the muffler outlet with the engine operating. The engine exhaust should have a distinct ‘pop’ against your hand. If not this could indicate a blocked muffler. Sometimes mufflers can be removed without much difficulty. If you’ve carried out the ‘pop’ test and it appears blocked examine the inside of the outlet pipe with a torch. You may see the blockage. This may be cleared with a small screw driver. If not, It may be a blocked internal ‘spark arrestor’. Take it to the service professionals, as it may need replacing.

7. Starter
Check for operation. Check the rope for fraying. Some machines have easily removable starter units allowing you to replace the rope. Take caution, as the rope will be under spring tension. If in doubt, leave it for the service professionals. Internal starting engines (small line-trimmers) can be quite difficult and timely to repair, therefore a service professional is recommended.

DIY Servicing: It's best to not be over confident. Sometimes servicing is best left to the servicing professionals. Damaging your machine can be a potentially expensive DIY project.  

ALWAYS refer to the operator’s manual for proper safety procedure and maintenance details. If it’s not in the operator's manual, maybe it's best left to the servicing professionals!