How to check the ignition depth is correct without having to disassemble the motor.
Without dismantling the engine, remove the spark plug and insert a length of solder to measure the "squish", or the distance between the piston at TDC position (TDC) and the cylinder head. This distance, called squish, must be between 1.3 mm. and 1.5 mm.
By inserting the solder and literally crush it with the cylinder head you can measure the thickness of the resulting solder crushed between the piston and the cylinder head. Remember that you must insert the solder until it reaches the cylinder wall and parallel to the pin and centered on the circle (see photos below)
Once satisfied that the squish is correct. See that the position of the flywheel is correct according to the scheme and provided with the piston at the point of maximum compression or PMS Measurement
Place the solder in the middle of the hole parallel to the piston bolt.
Measurement of solder after having crushed the piston against the cylinder head.
The distance between piston and cylinder head at maximum compression (piston at TDC) must be between 1.3 and 1.5 mm.
Gauge that is use to find the P.M.S. of the piston. It screws in place of the plug. It is the engine to manually rotate the piston up or down and so find out the PMS Tamper.
Once assured that the piston is at P.M.S. we see that the mark of the magnet and stator is 1.5 mm away from the coil.
