If your going to rig up some type of automotive temp gauge to your 4-stroke kart engine, I think suburban's Idea of monitoring your oil temp would probably be the way to go. This isnt normaly done so you'd have to figure out the best location and method to instal the sending unit in your motor. You'll probably find some of these gauges brand/models are a passive type design (sending unit permanently attached by a capillary type tube) and would not require a 12-volt source to power the gauge.
I have no idea what temp readings would be considered excessive but after you rode the kart around really hard in the summer for awhile you'd probably soon discover what's normal or too high.
note: you may find your oil temp ranges are higher than automotive coolant temp. gauge/senders go up to. I believe some gauges specifically made for engine/auto-transmision oil temps are designed to monitor up to a bit higher readings.
Many engines used in kart racing range between 375 to as high a 500 degree cylinder head temp readings running on gasoline. (methonal powered engines usualy run a bit cooler) These temp readings would have been taken from a race kart type temp (CHT) gauge that uses a sensor ring that simply slips around the spark plugs base before re-installing the plug.
Here's a link to the type of gauge I'm talking about here:
http://www.google.com/search?source...ie=UTF-8&rlz=1T4DMUS_enUS221US222&q=mychron+4
These types of kart gauges also have many other funtions and are powered from an internal 9-volt battery. They can typicly be found used in the $50 to $150 range and I think would be a much better altenative than trying to rig up a car type temp gauge.
