|Cylinder Head Temperature
Gauge by George Hagerty
Having read tons and tons of info on how the Chang runs hot and munificent (and I dare say almost admonishing advice) to let her rest and cool every 45 minutes of riding (did the really do this under wartime conditions?) -- I was concerned how to monitor my engine temperature. Shortly thereafter I came upon a guy and his wife in a brand new Ural sidecar rig waiting in line to get on a car ferry I was going on. We chatted about Changs and Urals and I went over his rig - he noted the overheating issue too and so had added an aftermarket cylinder head temperature gauge (CHT) to his handlebars. He had purchased the gauge from Aircraft Spruce - an aircraft specialty supply house since 1965. http://www.aircraftspruce.com/companyHistory.php
Understanding the Chang's engine spec to run at about 180-220C and having no way tell how hot she was I decided to add a cylinder head temperature gauge (CHT) too, as opposed to an oil temperature gauge.
1. I purchased a 2" round FALCON Dual CHT CR-002C and associated 14mm Senders from Aircraft Spruce. I liked the graduations in Centigrade - to keep with the Chang's metric upbringing. [They do make them in Fahrenheit.] Since she's likely never going to get hotter than 300C without a huge problem having happened, I chose the gauge range 0-340C - they have larger ranges but obviously not needed for the Chang. http://www.aircraftspruce.com/catalog/inpages/cr-002C.php?clickkey=651792
2. I made up a clamp to the handlebar using a #1 conduit clamp - see my description under "Voltmeter with On/Off switch."
3. Attached gauge to clamp, clamp to handlebars (including flat, stainless steel cable "zip" tie at bezel to support supplied plastic bracket), ran braided wire senders down to cylinders. Senders simply mount between head and sparkplug - EASY. Don't forget to order your senders - sold separately!
4. When wiring, I switched the leads so the orange indicator tip on LEFT = LEFT cylinder and orange indicator tip on RIGHT = right cylinder - not from pivot/axis of needle indicator as would be usual. A glance down is quick and easy - Left is Left, Right is Right - like writing on your Keds sneaker toes!
5. Under regular riding conditions, both my needles sit comfortably at 200C when cruising. The gauge gives me good info on how she's running - even at startup - told me once that one cylinder was cold - a stuck float. Now, by adjusting idle screws, I can dial in both cylinders to same temp - suggesting equal mixtures and good firings on each side. This gauge, coupled with tune-up adjustments and synching carbs keeps her quite smooth and quiet.
NOTE: They also make temperature compensated gauges and senders - mostly digital and bigger. These senders are simply analog and the ambient temperature around exterior of head, coupled with air temp will skew your readings slightly, but I wanted the older retro round gauge to match my voltmeter - these type were not temperature compensated. I will promise to rest her every 45min in the summer heat!