Runleader Digital Tach Hour Meter,Engine Temperature Gauge,Alert RPM & Temp,Backlights Display for Lawn Tractor Compressor Generator Snowmobile Marine Jet Ski Pit Bike

These are 26$, mount via a copper washer over your spark plug and can do tachometer as well. CHT Gauge About 400* F is about the max temp you’ll want on an aluminum cylinder. Cast iron can take a little hotter