If you are trying to choose between a 2 Stroke and 4 stroke dirt bike, or just want to know about the differences, this Article will give you info to help you decide which one is better for you.
First let’s talk about how the two engine types differ.
A 2-stroke engine works with no valves, makes power every stroke of the piston, and needs oil to be mixed with the gas (pre-mix) for engine lubrication. Most modern 2 strokes dirt bikes have oil injection systems so you don’t have to pre-mix. Two strokes are easy to identify by their FAT header pipes and their distinct sound: brapp…brapp…brapp!
A 4-stroke engine works with camshafts & valves, makes power every other stroke of the piston, and does not need oil mixed with the gas to run. 4 stroke dirt bikes have a more uniform sized header pipe.
Modern 2 strokes are used mainly for enduro riding/racing because then can idle lower which means they will stall less on the trickier sections of the trail. Because 2 strokes have no engine breaking, they wont be slowed done by the engine and will just coast when you are off the throttle.
2 stroke exhausts sound better than 4 stroker’s (in my opinion) 2 Stroke engines normally weigh less than a similarly sized 4 stroke which means the bike will accelerate quicker and be easier to handle going trough technical trails. 2 strokes engine have a powerband with a strong midrange “hit” that feel similar to a turbo kicking in.
Also because 2 strokes don’t have cams and valves, they require less maintenance compared 4 strokes you have to get the valves checked every 10 hours if you are racing or if you are just trail riding then you could go for over 40 hours to get them checked. You will only need to change the transmission oil on a 2 stroke because the engine oil is mixed with the gas.
If you are not racing then the regular maintenance on a 2 stroke will be less than a 4 stroke which makes it easier to maintain and cheaper, top ends on a 2 stroke are around $200 vs a top end on a 4 stroke can get up to $1700!
But, if you are looking for maximum power out of an engine, I would go 4 stroke because they rev higher than 2 strokes. This means there is no flat spot where you hit max rpm which makes them better on tracks with many corners or steep hills meaning at any given time their putting down more horsepower so will be quicker through the corner/up hill etc… 2 strokes can get just as powerful but need big bore kits fitted to do that while most high end 4 strokers come standard very close to what you can get from adding aftermarket.
If you are going to be doing a lot of dual sport riding(including street/highway) or competitive track riding, you are probably better off getting a 4 stroke. 4 stroke engines will get better fuel range compared to 2 strokes. All of the current top Supercross riders are running 4 strokes.
Some popular 2 stroke bikes made for trails are, beta xtrainer, beta 200/300rr, yz125/250x, ktm 150/250/300xc/xc-w
Also Some popular track 4 stroke bikes are, crf150/250r, yz250f, ktm250sx
Some good dual sport bikes, beta 500rrs, crf250/300l
I hope this blog post was helpful and that now your closer in finding out what dirt bike suits your riding style.