Two Stroke
Engine Diagnostic Sheet
General practice if there’s a problem
The correct fuel mix – 1000ml 93 unleaded petrol to 25ml 2 stroke oil
Fill the tank at least halfway
- Check key and barrel mechanism; ensure that the wires are all connected
- Insert key clockwise position – 1 click
- Put safety switch on the on position
- Firmly press rubber cap down on the kill switch
- Clean spark plug and ensure gap is 0.6mm and firmly press the coil on the plug to make contact
- Check for a spark by holding the spark plug with cord on engine and pull start
- Pull start the bike without giving throttle when the choke is activated (normally in the up position)
- Turn fuel tap on carburettor on – horizontal position
- Open screw – Wing nut at the bottom of carburettor and drain old fuel then mix new fuel
- Spray kwik start on the air filter for 1 second, put choke off and pull start
- Once you hear the engine starting, put choke down and throttle slightly and pull start again if needed
- Don’t throttle if choke is on, the engine will flood. Only throttle bike when choke is off
- Warm up the engine – start the bike, put the choke down and gently throttle
- Never throttle when choke is on, the carburettor will flood
- Position on the left of the engine. Remove the 4 bolts on the housing
- If the clutch has no linings. Then you need to replace the clutch
- Check that the springs on the clutch are not broken or disconnected and replace if needed
- Check that the chain is connected on the sprockets & adjust if necessary
- Turn spring screw located on the carburettor clockwise at half turn increments until idling increases
- Anticlockwise will reduce the idling
- Avoid throttling and stopping all the time, throttle constantly so the fuel can be ignited in the piston chamber
- Make sure the carburettor & air filter are cleaned regularly when riding in dusty surroundings
- Make sure the tank has enough fuel
- Check if any pipes are kinked that could be restricting fuel flow
- The carburettor could be dirty and over fuelling – clean carburettor and place back on the engine
- Check if the rubber gasket on the carburettor tap is blocking the fuel to the carburettor. Remove and clean the tap, reposition the rubber gasket with super glue to secure in place
- Check the wires from the cut off switch to the engine are connected
Pull start and carburettor problems
- Incorrect fuel mixture could seize the piston if to little oil is added to the fuel
- Check clutch housing and ensure the springs are not disconnected or any foreign object in the clutch area
- Piston could be seized – Try and turn the flywheel by hand, if it does not move take it to a mechanic to be assessed
- The ignition coil could be touching the flywheel, adjust the coil gap to the flywheel
- Spring in the pull start could be broken
- Replace pull start mechanism
- Easy pull starters must never be pulled hard and fast, these pull starters have a double spring system that assists you when pull starting
- Standard spring pull starters must be pulled hard and fast. They offer the most resistance and generally last longer
- Pull starters can’t be repaired once broken, you will need to replace the part
- Remove and clean carburettor with carb cleaner
- Remove jet in the middle of carburettor by turning anti clockwise then spray carb cleaner through the jet to free any dirt or blockages
- Dust particles are in the carburettor bowl and the fuel can’t shut off – open the carburettor bowl by unscrewing 2 screws and clean with carb cleaner. Ensure the rubber gasket is sealed & positioned properly when putting back the bowl
Chain, fuel and exhaust problems
- Move chain up and down 1cm from horizontal position when tightening
- Align and tighten and clean the chain, then spray with lubrication
- Check the fuel pipes are connected and clamps are on correctly
- Replace damaged pipes or filter and missing fuel clamps
- Black residue is a combination of fuel and 2 stroke burning
- NOTE – To some extent this deposit is normal
