Hi all:

I am thinking of getting a thermocouple to attach at the spark plug, to monitor the cyl temps.

My machine is an air-cooled 1988 Trail Boss 2x4 (2 cycle of course)

According to the Haynes Polaris manual I have, for liquid-cooled versions which have a fan, the fan comes on at 235 Fahrenheit.

I would think that my air-cooled model would run hotter than that, but have no clue how much (250 ? 300 ? more ?)

What would the expected temp range be for normal use ?

What would be the danger temp range ?

Anybody able to suggest a good product for this purpose ?


Thanks for any info.

Carl

 

You are concerned about a small matter as far as temp goes as thats why the cyl head has wide spaced fins to dissipate heat. This engine will only get hot (like all air cooled engines) if driven slowly for hrs say in a hot creek bed with little air circulation. As far as actual temp,I really never checked the old books I had at work on this since this is one of the two most durable engines Polaris has ever made!(500 water cooled being the second) Fans were added in the 90's but I personally NEVER had one come on no matter how long I idled or ran one while in the shop! Part of this could be where the sensor was mounted(on the top back motor mount bracket). This was a stupid location as far as I'm concerned,because it wasn't on the motor and didn't receive the heat directly from the engine. Don't worry, just keep oil in it,if scared of the oil pump system,just add 2-3 ounces oil to the gas as a precaution,keep the air filter clean,and if it has been rebuilt,should last you for YEARS! This was the only motor offered when I started with Polaris in 1988 whether 2x4 or 4x4 models and could go where larger machines could go! This engine I think actually got Polaris out of farm/ranch stores to main stream sales! Simple,but reliable! I think I've talked enough!! OPT

 

Thanks OPT, your input always valued ! Yes, this is a rebuild (new top end, replaced crank bearings and seals) , and yes, I am being paranoid. Oil pump is definitely working (we tested that, and also confirmed that the check valve for the oil opened at the documented 2~5 psi).

So, I should be good.

However, I am looking at the Trailtech Vector gizmo, seems like a slick little toy to have.

Carl