Just got back from four days of riding. I used the engine ice, 50/50 race gas mix and went to a colder plug. Bike ran fine with very little over heating but my son likes to plow the side hills and run the hole shots a lot. That is when we noticed the over heating, so essentially slower, lower gear riding. Never did heat up when we were on a longer run. One of my concerns was if the wossner piston and the tighter set-up would be creating more friction, thus more heat. Thanks for all replies - Ron
The
amount of heat the cooling system has to get rid of is a function of the power the engine produces. If the engine produces 10% more power, the cooling system will have to get rid of 10% more heat that it did when it was producing 10 % less power. Increase the power 50 %, the cooling system has 50 % more heat to get rid of than it did when it was producing 50 % less power.
Running the engine's air fuel ratio rich, will decrease the heat the cooling system has to get rid of in proportion to the reduction in power, plus the additional heat that is absorbed in the rich unburned fuel and carried out the exhaust port.
When or if the piston clearance becomes too tight, the friction between the piston and cylinder wall will generate enough heat on the surface of the piston skirt to burn up the oil film and seize the piston. The escalation in piston skirt surface temperature that causes a piston seizure happens over a very short time span of usually 10 seconds or less. If you are not having piston seizure problems, the clearances are not tight enough to raise the coolant temperature measurably in a two stroke.
Contrary to common folklore, running an engine leaner than the mixture that produces max power does not increase the coolant temperature significantly but can increase the exhaust temperature to the point that it may burn the edge of the piston next to the exhaust port. If the mixture is too lean, it will usually burn the piston before the coolant temps are raised high enough to raise a red flag.
About 70 % of my customers that are having an overheating problem are due to riding too slow and or have radiators that have the tiny fins peened over from gravel and debris striking these delicate little fins. If 20% of the fins are peened over, there will be approximately a 20 % reduction in heat dissipated by the radiator. If you have fins peened over, the fins can easily be straightened by pushing a zip tie of the appropriate width through the radiator from the back. It will usually take less that 30 minutes to straighten a radiator that has all of the fins peened closed.
In all of my years of developing and testing two strokes, I have not found a coolant that improves the heat transfer from the engine to the coolant or improves the heat transfer from the coolant to the radiator enough to justify the cost of these coolants with magical properties. If you have to use these magical coolants to keep your engine temperature off of the red line, you have other problems that need to be addressed.
A colder spark plug will not reduce the engine temperature one degree unless the previous heat range was causing detonation. Too cold of a heat range will decrease spark plug life and increase the probability of fouling.
