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Before You Choose an ATV, Find Out Which Engine Type is Best


If you've been around ATVs, dirtbikes or other small performance engines for any length of time you're probably familiar with the age-old debate between 2 stroke and 4 stroke engines.

What you may not be familiar with is that the many facets of this debate are moot points.

Mechanical Differences Between 2 Stroke and 4 Stroke Engines

The biggest difference is the number of times the cylinder fires during a stroke. A "stroke" comprises of Intake, Compression, Combustion, Exhaust. A 2 stroke engine will do this by moving the piston up and down 1 time, a 4 stroke engine will take 2 times.

In other words a 2 stroke engine has a "power" cycle every time the piston moves up and down once, and a 4 stroke engine moves up and down twice to make power.

As you can imagine, you get more bang for the buck with a 2 stroke because you get more power with the same size cylinder.

Misconceptions About the Difference in 2 Stroke vs 4 Stroke Engines

There are a few common myths people use when comparing 2 and 4 stroke engines.

The most common is that 2 strokes have to have pre-mix. (Mixing gas with oil). This is only a matter of simplicity. Take a look at Caterpillars; they have huge oil sumps, they have oil pressure AND they are 2 stroke engines.

Valves at the top of the cylinder head in 4 stroke vs reeds in cylinder walls on a 2 stroke is also false. Cruise ships have turbo diesel 2 strokes with poppet valves.

Emissions and Maintenance

People will also try to tell you that 2 stroke engines produce more emissions than 4 strokes. In general this is true. But there have been huge advances in technology that has made 2 strokes able to run as clean as 4 strokes. Surrich/Orbital 2 stroke design on Mercury outboards is a good example.

Maintenance is more frequent on 2 strokes because they fire more and run hotter. You can expect to re-do the heads every few seasons. Fortunately, 2 strokes are much simpler and therefore easier to work on.

The Bottom Line: Power!

So, what's the difference? About the only difference between 2 stroke engines and 4 stroke engines, besides the number of times they fire in a cycle, is the amount of power they can make given that everything else is equal. Because the 2 stroke fires more often than a 4 stroke (twice as much as a 4 stroke), it naturally makes more power.

Voice Your Opinion!

Like all debates, one person can rarely cover all sides. My opinions come from years of hands-on-experience and research. What's your opinion and how did you come to those conclusions?

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