Such as Honda CH125 water-cooled scooter, its minimum ignition speed is 300 r/min. If the minimum ignition performance reduces, the minimum ignition speed increase, and it sometimes even need to reach more than 400 r/min to ignite. If the repairman still use simple arcing tests as above, then they may be fooled by some false appearance and even mislead. This is because there is no compression resistance in the cylinder when the piston runs up and down without spark plug in the engine; the start speed is above 400 r/min, which is much higher than but after putting it on engine and then apply electric start or pedal starts, then, there is certain pressure inside the cylinder and the running resistance will increase, start speed will be only about 300 r/min. If the battery voltage is low, then the start speed is even lower, which can’t meet the minimum ignition speed, of course, the motorcycle will not start