In 2019, 197,220 ATV bikes were sold in the U.S. alone. While this number is less than the year before, it is still staggering. The number of deaths per year, related to ATV accidents has ranged from 550 to 650, and sometimes going up to 800. Most of these have been due to engine failure. 

Poor or reduced engine performance is the leading cause of ATV bike accidents. These are the signs that you need to look out for to know that your 125CC 4 stroke engine needs replacement. 

Loss of Power

Usually, ATV bikes use internal combustion engines. They use a four-stroke combustion cycle to turn gas into power that runs your vehicle. Intake stroke, compression stroke, the combustion stroke, and exhaust stroke are the four strokes. If any of these strokes is experiencing a hiccup, then your engine will lose power.

The piston is the most critical component of the engine, used in ATV bikes. Typically a four-stroke engine's piston and ring need to be replaced every 15-30 hours of use. Check the service manual to know your bike's piston replacement threshold. 

Reduction in the Mileage

If you begin to notice that your bike is not giving as many miles per gallon of gas as earlier, then you need to worry about your engine's health. It could be a result of problems in the compression stroke of your engine. 

A fuel cleaner may help solve the problem temporarily, but it is best to get the engine checked out. Don't wait too long after the signs of low mileage begin to appear. 

Stalling Engine

This is highly unusual and is a result of a problem in the engine. It will probably be due to the intake stroke not receiving the right spark. Get the vehicle checked out immediately. If unchecked, it can lead to more significant issues in the future.

Off Odors or Smell

If you begin to notice off smells while the engine is running or after it is turned off, it can be a sign of engine failure. Please don't ignore this as it may be due to problems in the exhaust stroke. 

An internal leak can cause the coolant to burn and give out a sweet smell and white smoke from the exhaust. If the head gasket or intake gasket has cracks, it can result in the leak. Have your 125cc 4 stroke engine replaced immediately.

Ticking Noise in Engine

When your bike's engine is failing, it will result in a ticking noise. This is because of the oil burning off. Clogs or old spark plugs can be the reason for this. A low battery or improper octane in gasoline can also cause this. 

The engine will have its usual noises, but when the cam chains are stretched, or if there is not enough tension on the chain, it can increase the intensity of the sound. It may require that you change the engine immediately. 

Knowing the signs of engine failure is key to maintaining your bike's health. Engine failure can result in accidents and fatalities. To avoid this, you need to make sure that you have your bike serviced regularly and replace the engine at the first sign of trouble.