If the ATV smokes upon starting, there is nothing to worry about, as that is condensation burning off. If it happens early into the ride but dissipates later on, or only happens when you are revving your engine, you probably have an issue with the valve seals or piston rings. Color also matters. White smoke is fairly standard and not a cause for huge concern if it happens early into the ride, while black smoke means you’re burning gasoline which is a very bad sign. Blue smoke, on the other hand, means you’re burning oil. This isn’t a big deal on a 2-stroke quad but can be on a 4-stroke quad.

Failures within the engine system can be tougher to put your finger on due to the high volume of mechanical parts required to make it all run. Starts and stalls, or a complete lack of engine action could be caused by simple fixes like a clogged air filter or exhaust, or more in-depth issues such as blocked fuel lines or over-fueling causing carburetors to flood.