blank 04/05/13 11:30AM Dirt Bikes, Dirt Bikes 101, Four Stroke, Motocross, Two Stroke

Two Stroke vs Four Stroke Dirt Bikes: What's the Difference?
Guest Blog

Okay, it's been about fifteen years since Doug Henry catapulted the Yamaha four stroke dirt bike onto the forefront of the motocross scene, and the 2t vs. 4t debate has been raging ever since. There shouldn't be any debate at all about which bike is "better" because they're both great bikes, and each rider will have their individual preference based on riding style and experience. A two stroke isn't better or worse than a four stroke - it's just different.

Many riders find the current crop of four stroke bikes easy to ride with their smooth, tractable power delivery but not all riders, especially those with some experience, want that predictability. They prefer the thrill and adrenaline rush of hitting the powerband of a snappy two stroke. So what's the difference between a two stroke and a four stroke?

Two Strokes

The two stroke engine involves two processes: compression and combustion. The engine fires and the spark plug ignites once every revolution of the crankshaft. It's a simpler process with fewer moving parts, which makes them easier to work on and lighter in weight than a comparable four stroke. Since it fires on every revolution, it is roughly twice as powerful as a four stroke engine, which is one of the reasons they allow 250cc two strokes to compete with 450cc four strokes on the motocross track. There are diehard two stroke fans that wouldn't be caught dead on a four stroke, but there are a few characteristics of two strokes that some people may find objectionable:

  • the two strokes require a mixture of gas and premix oil, so you need to be sure to have extra oil on hand. You may be able to find someone in the parking lot willing to donate some gasoline, but without the premix oil, the gas does you no good.
  • the two strokes tend to smoke when first started up, which may annoy your neighbors and any environmentalists that might be nearby
  • although the sound is not as loud as a four stroke, some people do not like the higher frequency 'buzzing' sound of a two stroke
  • they can be difficult to ride due to their unpredictable power delivery

Most two stroke fans will say these objections are outweighed by the positive aspects:

  • since there are less moving parts, they are less expensive to maintain and easier to work on
  • the sound of a two stroke does not travel as far as the sound of a four stroke
  • they're lighter, more nimble, and easier to maneuver
  • they are an absolute blast to ride due to their unpredictable power delivery

Four Strokes

The four stroke engine involves intake, compression, combustion and exhaust. It fires only once every two revolutions. The power delivery is steady and predictable making them a great choice for beginners or rusty riders, but four strokes bikes have their share of detractors as well:

  • they require a bit more maintenance
  • motocross four strokes are very loud
  • more moving parts means more things to break and additional weight
  • some riders say they're too easy to ride due to their predictable power delivery

The flip side however, has many positives:

  • the gas and oil are separate, which can be an advantage; if you run out of gas, as all you need is a gas can
  • the motocross bikes are loud, but they can be modified to bring the sound levels down
  • with proper maintenance they will last a long time between major overhauls
  • there are many more four stroke models to choose from than two stroke models
  • a four stroke is more fuel efficient than a two stroke
  • they are very easy to ride due to their predictable power delivery

The four stroke bikes are evolving and improving every year. Almost all the 250cc and larger dirt bikes now use fuel injection, with Yamaha the last manufacturer using a carburetor (but that's rumored to be changing this year). To a certain extent, your two stroke vs. four stoke choice is a foregone conclusion since three out of the Big Five are no longer making adult two strokes. KTM and Yamaha are the only ones offering adult-sized two strokes bikes.

So which is better? The short answer is: neither. They're different bikes built for different purposes. It's like asking which is better; an acoustic guitar or an electric guitar? Both guitars are great instruments made for creating different types of music. They both provide hours of enjoyment and bring people together to relax and socialize, and that's exactly what dirt bikes do. Buy the bike that best suits your abilities If you're a beginner or the least bit apprehensive, absolutely start with a four stroke and work your way up from there.

Thanks for reading my article. I've recently re-vamped my website ( ), so stop by if you get a chance.

Article Source:

blank Permalink | Print | E-mail | Comments (2)