running hot... overheating 2 stroke

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Spit test isn't accurate. You should place your tongue against the cylinder head. If you can keep it there for 3 seconds before it burns your engine si running at correct temperature, if it burns instantly, too lean, if it takes longer than 3 seconds for it to burn, too rich.

Its just that easy.


The best way to tell if you are overheating is you are experiencing performance loss at full throttle. I ran my bike for 15 miles up a steep Colorado mountain last summer and my exhaust pipe was RED and engine head changed to a duller grey color. Did I overheat my engine? Apparently not, it never seized and kept chugging along without any loss of power or speed.
 
chances are you need a cooler plug(spark).. the cooler the plug the less local the fire hence allowing your engine to not race the temp up. Cooler plug richer carb setting (needle higher up) jet boaring (fuel mixture richening technique)? Check out a cooler plug first bud!
 
"Richer oil ratio means leaner air/fuel mixture and leaner means hotter."
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"So fuel mixed at 16:1 is hotter cyclinder temps vs 20:1 runs cooler? Seems that more oil will burn the fuel slower and less heat"
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Huh? Which is it?
 
There are 2 things to consider about mixture:

1. Air to fuel ratio. Your carburetor ensures a proper mixture occurs so engine isn't run too rich (too much fuel for a given amount of air or not enough air for a given amount of fuel) or too lean (not enough fuel for a given amount of air or too much air for a given amount of fuel) HT carbs only allow for high speed mixture setting by adjusting needle height. There is no low speed or idle mixture screw to fine tune the carb.

2. Oil to Fuel mixture: The more you displace fuel with oil, there is less fuel to burn for a given amount of air. Therefore, more oil (or richer oil to fuel ratio) causes an effective leaning of the mixture.

Given the above, this is why I never run at 16:1 even when new. I usually run 32:1 when new and then lean it out to 50:1 using my secret oil that is obtained from pressing a bean...a bean that cannot be legally owned in the USA.
 
I have checked head temperatures on most of my air cooled engines with an infared thermometer and the run in the 260 to 290 degree F range so it is no suprise that the spit test wil sizzle. My motored bike engine is a 2 cycle engine that I bought from DAX. In my case the carburetor was set up excessively lean and I ended up drilling out the main jet several # drill sizes to get it to run correctley. After you make a run check your plug color to see if you are running too rich or lean. If it is white you are too lean.
 
290 deg F is not too hot at all for a 2 stroke engine. I run my model engines at 310 max temp but only if I have a touch of castor in the fuel.
 
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