There is a lot of confusion when it comes spark plug heat ranges. Many customers ask me for a "Hotter" plug assuming that this has something to do with the spark output. It does not. Spark plugs are made in different heat ranges & can be identified by the number stamped on the plug. The lower the number the hotter the plug generally but not always ie: Champion plugs are the opposite. The plug heat range determines thet temperature that the plug is designed to run at & has to be matched to the application. As you can see in the picture below the difference in heat range or the temperature that the plug body runs at is determined by the length of the heat path taken from the plug firing end to the cylinder head. If used outside of it's designed heat range the plug may foul or overheat. It doesn't effect the spark quality or engine temp in any way. Generally, there is never a need to alter the stock heat range unless the engine has been heavily modified.
You can easily check for drive chain wear by seeing how far you can pull the chain off the rear sprocket (see picture). If you can pull the chain off more than one third of the height of the sprocket teeth than the chain is in need of replacement sooner rather than later. Keep in mind you need to replace the front and rear sprockets at the same time or you will significantly reduce the life of the new chain.
I am sure most of you have noticed a loss in engine performance on very hot, humid days. Why is that? Both higher heat and humidity will reduce the amount of oxygen in the air that the engine ingests. Hotter air temperatures thru reduced air density and higher humidity thru the water vapor displacing oxygen. As an engine uses oxygen combined with vaporized fuel in the combustion process there will be less heat is produced in the combustion chamber there creating less cylinder pressure. Less pressure equals less push on the pistons which equated to less power at the wheels.
I have been involved in mechanics and motorcycling from a young age. I formed Cycle Improvements in 1981 and still have the same passion to learn today as when I started. Hope you find this blog interesting and educational.