4-stroke Dirt Bikes are quickly replacing 2-strokes in the market and are an excellent choice for trail riding and motocross. For the less-experienced rider, 4-strokes are a bit easier to handle since they don’t usually have a big power band to manage (a “power band is a range of higher engine rpm where the power quickly increases, usually by a lot). I remember riding a Honda XR-80 when I was young and how much fun that was. It was a basically a motocross bike for kids (not really little kids) and was perfect for trails. In those days, compared to a CR-80 (2 stroke), the XR-80 was much more friendly and easy to ride. 
Take a look around today, and you will find a lot of great new 4-stroke dirt bikes in all sizes and for new riders and experts. The best thing about 4-strokes is that you don’t need to worry about mixing ratios of oil and gas, which if you get wrong will ruin your engine. Another great thing is that they don’t pollute as much and normally are not nearly as loud, unless you add a high performance exhaust system.
The larger single cylinder 4-strokes are commonly called “thumpers” because of the thump-thump-thump sound of the engine. Personally, I love that sound.
If you like dirt bike riding and motorcross, but have never seen the old Steve McQueen movie, “On Any Sunday”, do yourself a favor and go rent or buy it. Not only was he an enthusiast, but he was also a competitor and a collector. In fact, one of his antique motorcycles, a 1937 Crocker, sold for $276,000 in 2006.
