This weekend I had a great experience taking a group of new dirt bike families out to the D36 Grand Prix at MMX Racing. Both kids are about 12 years old. One of them has a KLX 110, the other family is currently in bike search mode.
We talked about the different type of racing disciplines, and during that conversation we got on the topic of bikes. 2 Strokes vs 4 Strokes, MX, vs Off-Road, etc. One thing I quickly realized is how confusing it is to new riders. Not only do you have 2 Stroke, 4 Stroke, MX, Trail, Off-Road, their are actually two styles of 4 stroke bikes. The TTR, CRFs of the world, vs the YZ, CR type bikes.
So here is my take at “The Newbies Guide to Dirt Bikes – Racing Edition”. I hope to make it as simple as possible for those new to Motocross/Dirt Bikes to understand what is available.
Common Terms
Some words you may have come across already:
- 2 Stroke
- 4 Stroke
- Motocross
- Cross County
- Trail
- Offroad
- Enduro
- Trail Bike
2 Stroke vs 4 Stroke
Let’s start with 2 Stroke/4 Stroke. This conversation WILL get in the weeds very quickly about what is better and why, with 2 very distinct camps. What I am explaining here is the difference at a very high level. When you hear 2 Stroke or 4 Stroke what they are referring to is the motor or engine of the motorcycle. Inside the motor is a piston. That piston travels up and down inside the motor making the magic that motors do. A 2 Stroke has to perform 2 sequences of movement in the engine, while the 4 Stroke does 4. Now in reality, it’s much more complicated, but for our Newbies Guide, this should get you going. Next time you are out at the track, listen carefully. You will hear two distinct sounds from the different bikes. 2 strokes have a “snappier” sound while the 4 strokes have more of a “grunty” sound. The easiest way to tell the difference while looking at a bike, is the 2 Stroke will have a bulbous pipe coming off the engine, while the 4 Stroke header pipe will be more tucked in near the motor.
A 2 Stroke bike - notice the bulbous expansion chamber pipe
A 4 Stroke bike - notice the more compact header pipe
Dirt Bike Disciplines
Next we will tackle some of the Dirt Bike Disciplines. Motocross, Trail, Off-Road, Cross Country, Enduro are all types of riding/racing. Motocross is often used as the over arching term. The term Motocross bike and Dirt bike are basically interchangeable. In terms of racing/riding conditions, Motocross is done at a Motocross Track. MMX in Marysville is an example of a Motocross Track. Going riding out on single track at a place like Foresthill or Hollister would be referred to as Off-Road or Trail riding. Cross Country and Enduro are more related to racing disciplines.
Cliffs Notes version: Motocross is at a closed course track, Trail/Off-Road is at an OHV Park or out in the woods somewhere.
Motocross vs Trail vs Off-Road Bikes
So what makes a bike a Motocross bike, vs a Trail Bike vs an Off-Road Bike?
Motocross bikes are generally suited for advanced riders, or those wanting to ride at higher speeds with an aggressive riding style. They come in both 2 Stroke and 4 Stroke. We will cover how and why a bit later in this article. These are what you see on TV in the Motocross/Supercross races, or the Freestyle guys hitting all the jumps. They are the latest technology in terms of motors and suspension. This is also what you will typically see at any of the local Motocross tracks. The Yamaha YZ series, the Honda CR series, and the Kawasaki KX series are all examples of Motocross bikes.
Trail/Off-Road bikes are generally less aggressive. The motors and transmission are meant to be ridden at lower RPMs. They are almost exclusively 4 Strokes. 4 Stroke engines can be more easily ridden at lower rpms. You will typically see these at OHV parks and other Off-Road areas. These make great bikes for people to learn on because of the less aggressive characteristics. The Yamaha TTR series, the Honda CRF series, and the Kawasaki KLX series are examples of the Trail/Off-Road bikes. One quick way to identify a Trail/Off-Road bike is to look at the front end. The forks will look different than a Motocross bike. Some models may have a headlight/tail light as well.
A Trail/Off-Road bike - notice the different fork design
A Motocross bike - aggressive styling with performance suspension
Engine Sizes and Displacement
Okay, so we have tackled 2 Stroke vs 4 Stroke at a high level and we have tackled type of bikes. Now it’s time to dig in a little deeper into sizes. You may have heard the terms 250, 125, 450, 85 etc. Those terms are referring to engine displacement. 125 is a 125 cubic centimeter motor. A 450 is a 450cc engine, so on and so forth. Here are the typical engine sizes.
Motocross Bikes
- 50cc - 2 Stroke
- 65cc - 2 Stroke
- 85cc - 2 Stroke
- 125cc - 2 Stroke
- 250cc - 4 Stroke
- 450cc - 4 Stroke
Trail/Off-Road Bikes and Play/Pit Bikes
- 50cc - 4 Stroke
- 110cc - 4 Stroke
- 125cc - 4 Stroke
- 140cc - 4 Stroke
- 230cc - 4 Stroke
As you can see there is overlap in size. What is the difference between a 125cc Motocross Bike and a 125cc Trail/Off-Road bike? Remember one is going to be more aggressive, while the other is more subdued and easier to ride. The other difference is actual bike size. The height of the seat being very different.
We will use the specs from the 2021 Yamaha Models. The YZ125 vs the TTR125. You should be able to pick out which is which from what we have learned so far. Hint - notice the pipe and the forks.
Left: YZ125 (Motocross) - Right: TTR125 (Trail)
Seat Height for the YZ 125 on the left is 38.4 inches, while the TTR 125 on the right is 31.7 inches. Both are 125cc machines.
A few more pieces of information. For very small kids (3-6 years old) they will start on a 50cc four stroke. The Honda CRF50 or the Yamaha TTR50. Yamaha also has PW50 that is very slow and very easy for kids to learn on. You can outfit them with training wheels. From there, Motocross bikes for kids that want to race or really ride aggressive will be 2 strokes. The 50cc, 65cc and 85cc are 2 strokes are all very fast, very nimble machines. Be aware of that as you shop for your kids bikes.
As you get bigger and move into young teens and adults you will be looking at 125cc and up. In Motocross land, a 125cc 2 Stroke and 250cc 4 Stroke would race in the same division, as well as 250cc 2 Stroke and and a 450cc 4 Stroke would race in the same division. Remember way back at the beginning of this I told you about the 2 camps, 2 Stroke vs 4 Stroke. This is where that tangent/conversation would start and I am not opening that can of worms right now. This is the Newbie Guide.
One important note for the new rider/family: 2 strokes require you to premix your gasoline with oil. This is not a difficult process, but you do have to plan ahead. With a 4 stroke you can just stop by any gas station on the way to your riding destination and put in some 92 octane fuel.
Choosing Your First Bike
You are now armed with enough information to be dangerous. What do you pick as the Newbie Dirt Bike Rider? Well I can’t make that decision for you but I can refresh your memory and provide some general tips.
Consider a Trail/Off-Road bike if:
- The person is under 5 years old (TTR50, CRF50 or PW50)
- The person is brand new to riding 2 wheels
- The person is generally less aggressive or timid
- You’re looking for a bike to take along on camping trips and just cruising around
Consider a Motocross bike if:
- The person is coming from a background of racing/riding BMX, or Downhill MTN biking
- The person wants to race or feels like the Trail/Off Road bikes are just not fast or nimble enough