Many of us have driven a car and turned on the cruise control. We will be driving down the freeway and suddenly see a cop and then say hey we should put the speed back to 55, so we throw on the cruise control.
What we don’t really notice happening is there is an automatic system occurring when the vehicle starts to go up the hill. That the car starts to (by its nature because it’s heavy) to slowdown. It goes to about 50 mph then the governor kicks in or the cruise control kicks in only to get up over the hill then the car steadily decreases in speed, because the cruise control backs off the throttle causing the car to slowdown.
What we are talking about is a control system or a governor designed to maintain speed of the engine under load. What you’ll find is that there are various pieces of equipment that have governors on them.
For instance a generator has a governor on it so that it will not over rev. You need to have 3600 RPM so that you can maintain the 60 Hz required for proper power generation for tools and lights so that you do not burn’s things out. A governor is put on a generator to maintain its speed. What happens is if you ever listen to a generator is that it will suddenly increase in speed, or it will sound like it’s lugging away when you turn on your drill or your saw. It is because the governor has kicked in. And then when you turn off your saw then the engine turns back to a different sound like it’s backed off the throttle.
Lawnmowers have governors, wood chipper’s have governors: any device that requires maintained speed has a governor on it. Items that don’t have governors on them would be like a weed wacker or a chainsaw., A chainsaw for example can actually rev way up or get to top speed.
On a go kart you want a governor to maintain speed, especially when dealing with smaller children, who are going to be riding the go kart. The reason for that is that a small child may not understand the intricacies of the throttle and the brake and may accidentally stomp on the gas instead of the brake, unfortunately maintaining it stompted. If the go kart engine did not have a governor in place you could actually over rev the engine.
The nice thing about a governor is that it sets the rev limit, so that if the child wants to stop on the gas to the floor, then it will not actually go up to 6000 RPMs, but it will only go up to 1500 RPMs if he set it that way. And that is a nice feature to have because then the go kart will only go so fast. You’ll see that a lot on go carts in amusement parks where they will set the governors so then they go carts will not go superfast.
If you take a governor off an engine there is a danger to the engine in that you can overheat it. For instance a Briggs & Stratton, Tecumseh and the Wisconsin Robin type engines are designed to run at the most at 3600 RPMs. When you go beyond 3600 RPMs you start to get up to 5200 RPMs you are running in danger of actually overheating the engine. The valves are not designed to actually handle that: to dissipate that type of heat. The cylinders will start to wear out, the cooling system in general is not designed to handle that. So you have to keep the valves and cooling system in mind if you are running your engine at an excessively high speed above 3600 RPMs for a prolonged period that you will actually prematurely wear out your engine
The real issue comes down in that when you start and just run your engine really fast the thermal or the chemical side of things in the engine gets very, very hot and the heat convection is not sufficient for the the engine so it will overheat. If you read the engine manuals on these engines they warn on over revving them.
The damage that occurs first is that you burn out an exhaust valve. If you keep that in mind then you’ll just have to have a routine maintenance program where you replace exhaust valves or grind them down. What happens is the exhaust valve becomes cherry red and breaks down and becomes pitted and doesn’t seal as well. In the long run you will start to run out of compression and will have power loss because of the heat breakdown.
Governors are designed to protect the engine from over revving and overheating. If you understand that fact and you know that is designed for the engine’s protection and for your protection just keep that in mind.