Mercury two stroke engine operating temp pls ???

[merc_racer]

HI all
i have brought a "trail tech " brand digital spark plug temp guage for my 40 hp short shaft mercury 3 cylinder jap spec two stroke out board engine.
the sender unit locates under spark plug to get reading!!

1/ which cylinder should take the reading from please ?

the top,near thermostat,the centre cylinder or the lower cylinder closest to the water pump please ?

2/ next question,what would be considered the normal operating temp of my engine above please ?

i was told approx 60/65 degrees celcius ?
thanks guys

[merc_racer]

what know one knows what the running temp should be ?????????

[kingsbiship]

You're not asking what the running temp. is... you're asking what the temp. is at the base of the spark plug,
which is probably the hottest spot on the engine! If you can easily install and re-install the sensor (which
sounds like you can) .... try a few engines and obtain an average reading. The center cyls. are usually the hottest!

[merc_racer]

You're not asking what the running temp. is... you're asking what the temp. is at the base of the spark plug,
which is probably the hottest spot on the engine! If you can easily install and re-install the sensor (which
sounds like you can) .... try a few engines and obtain an average reading. The center cyls. are usually the hottest!

G,DAY MATE,thanks for reply/info!
apparently tohatsu tech dep said normal operating running temp is = 65 degrees celcius!!
sothe sender under the spark plug is the hottest part of the engine nearly is it ??
i dont have access to other types of engine mate.
did some testing with my power pipe and temp guage today,idle temp warm @ 50 degrees celcius,flat out racing,approx 120 degrees celcius temp and max temp at one stage was 137 degrees celcius,wow!!
so in the piston area or exhaust side,i wonder what temp
it is at then roughly ,any ideas pls ?
cheers

[kingsbiship]

Do a search... guys put pyrometers in the cyl. heads all the time here. Sometimes in both heads!
See what they are reading and compare!