Lots of Far-Eastern scooters are fitted with GY6 engines. These already elderly units are sturdy and economical, but if you want to “push” the power a bit (so called ‘Racing’ kits, better handling of the advance, etc.), you soon find yourself faced with the problem of the engine temperature, and it becomes essential to f it a heat sink (of ten wrongly referred to as a ‘radiator’) on the oil circuit. Even so, in these circumstances, it’s more than reassuring for the user to have a constant clear indication of the oil temperature. Here are the specifications we set for the temperature gauge we wanted to build: Oil Temperature Gauge Circuit Diagram : no moving parts (so not meter movement), as scooters vibrate a lot!; as cheap as possible (around £12); robust measuring transducer (avoid NTC thermistors and other ‘exotic’ sensors); temperature range 50–140 °C. (122 – 291 °F); audible and visual warning in case of dangerous temperature; compact; waterproof. Let...