350X Head Temperature Range???

[MN250R]

Anyone know what a safe temperature is for a good running ATC 350x?
I have an 86 and am installing a trail tech head temp guage on, and was just curious what they should be running for temp.

Thanks!

[oscarmayer]

it will vary greatly on an air cooled motor. it will range from 170-250 depending on how hard and how long you push it. temps in the 300's is not good. that typically means your running lean.

[MN250R]

Awesome Thanks!

[BOB MARLIN]

Report back with what you readings you get.

[dougspcs]

Seems a bit pointless to me..just for the reason that head temp will vary so dramatically with load, speed and ambient temperature. A liquid cooled engine I could see such an exercise.

If its combustion chamber temp you are concerned with as you're trying to work out carb jetting then an old fashion plug tip read would be more accurate. If you're plug comes out white then beware..you're gonna burn your piston or valves.

But if you're just a gauge geek..I'd consider seeing if you can fashion up an oil temp gauge in line to the cooler. That could be more useful information than head temp.

[MN250R]

Well, I went riding today with a friend on his banshee. Temperature was 82 degrees out. Temperature varied from 400-450 on the gauge for head temperature after running for a while. This is completely stock motor, stock exhaust, brand NOS 86 350x carb, factory jetting, new air cleaner with lid on. Ran awesome all day! I checked the plug and it was tan.
They definitely run hotter than liquid engines.

[The Goat]

What oil are you running? Something isn't right.

My money is on your sensor pulling an incorrect reading.

Anything that high and your valve seals are going to take a dump.

Buy a cheap IR thermometer and shoot the head.

My money is your sensor is reading exhaust temp.

I have run a 300 honda up to 350+ while spraying, it started blowing light smoke as the valve seals failed from heat. With an oil cooler installed my oil temps stay right around 195 degrees. That's running gn4 10w40. It falls a bit more when running full syn motul.

[MN250R]

Im running Valvoline atv oil 10w-40. Im gonna use rotella T next. My head temperature probe goes under the spark plug. That's possibly why its so high of a reading? I will use my IR thermometer on my next ride here in a couple days. Do you have an oil temp gauge installed?

What oil are you running? Something isn't right.

My money is on your sensor pulling an incorrect reading.

Anything that high and your valve seals are going to take a dump.

Buy a cheap IR thermometer and shoot the head.

My money is your sensor is reading exhaust temp.

I have run a 300 honda up to 350+ while spraying, it started blowing light smoke as the valve seals failed from heat. With an oil cooler installed my oil temps stay right around 195 degrees. That's running gn4 10w40. It falls a bit more when running full syn motul.

[RubberSalt]

You could also test your sensor, toss it into the oven and read the gauge. Then double check the oven's accuracy with a thermometer next to the sensor.

If your into gauges, I'd grab an oil temp as well as an egt sensor+probe. Those exhaust temps will tell you that your over heating pretty dang fast. Ask the diesel guys or turbo guys about them.

[oscarmayer]

I would think your running lean.


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[DohcBikes]

Seems a bit pointless to me..just for the reason that head temp will vary so dramatically with load, speed and ambient temperature. A liquid cooled engine I could see such an exercise.

If its combustion chamber temp you are concerned with as you're trying to work out carb jetting then an old fashion plug tip read would be more accurate. If you're plug comes out white then beware..you're gonna burn your piston or valves.

But if you're just a gauge geek..I'd consider seeing if you can fashion up an oil temp gauge in line to the cooler. That could be more useful information than head temp.

Head temp is a very valid and useful reading for monitering the health and efficiency of an air cooled engine.

What you are measuring under the plug is combustion chamber temp. The optimum values for this test will differ greatly from the optimum values for a head temp test. I can explain further if necessary.