I've been using these meters to monitor my cylinder and head temps on my BBK kit engines and they work great for a decent price. I used products "weather proofing" that try to make the meter weather proof since I got this meter mounted on my handle bar via a smart phone holder.

ebay price is around $16 plus with free shipping.
https://www.ebay.com/itm/Digital-2-C...AAAOSwkfxb3-sL

you can see both of my groms have these meters. I have one channel going to the head and the other channel going to the cylinder using the bolts that are on the head and cylinder.

Your average temperature is about 285-320F
Cheap dual temp meter to measure engine head and cylinder temp, ebay-img_4727-copy.jpg