Here's an excerpt from one of the many posts like this from a while ago. Hopefully it helps, although it may be a bit dated.
Originally Posted by
draze 
Thanks for all the replies guys!
You all talk like pro's and loose me quite often, I've reread most of the posts more than 4 times and still can't keep up.
How do I know which is a motocross bike and a trail bike?
I was not thinking of any extreme jumps and probably will not for long time. By getting into dirt, I meant trail riding. I am not considering a 450, thinking it's too much power and more expensive than 250. I was thinking of buying a used bike (2000$ max) and a used trailer.
Bikes are a big mystery to me for now, so I try to be like a sponge and soak in all the information, so throw anything you think might be useful for me.
Cheers.
Heres a post I made a while ago on the different categories of bikes and there differences. Its hardly all inclusive but it might help.
Can someone correct me where I'm wrong please? However differences between bikes is basically
MX bikes: Built for riding around a track in compettition.
- shortish gear range. Meaning more power oriented and less top speed oriented but more balanced than an SX bike.
- kick start only (with the exception of KTM).
- No kickstand so you'll always have to find a tree to prop it against, again with the exception of KTM (not really an issue in the ganny most of the time tbh. I have a kickstand and still use trees).
- Small fuel tank, probably smart to bring a jerry can and keep going back to your car/truck.
- Stiffer suspension tuned for higher speeds and gives lots of feedback, more likely to tire you out faster.
Bikes in this category:
KTM SX, SX-F
Kawasaki KX, KX-F
Honda CRF-R, XR
Suzuki RMZ
Yamaha YZ, YZF
SX bike is similar to MX bike usually same model (I believe some companies make SX specific bikes?) but even shorter gear range and differently tuned suspension.
Enduro Bikes: Built for offroad racing with minimum road safety equipment(lights at least) for stretches of the race which are on road. Some of them can be blue plated.
- Taller gears, and in some cases more gears. But still more power oriented than speed.
- Electric start is more available on these models I believe
- kickstands are not likely to be on them since they're race bikes with the exception of KTM
- Larger fuel tank
- Stiffer suspension than Dual Sports but possibly softer than MX bikes
- Spark arrestors are more likely to be equipped on these
Bikes in this category
KTM XC, XC-W, EXC(previous 200
Kawasaki KLX, KDX
Honda CRF-X
Suzuki RMX
Yamaha WR
Dual Sport: these bikes are designed to be blue plated bikes. They very quite a bit in capability however and could use some sub categories. Some of them are just blue plated enduro bikes and others are more road bikes that can be taken into the bush.
- Likely Tallest gears out of all the bikes
- Lights, Signals, Chain guards, Mirrors. They're designed to be blue plated.
- Electric start is likely standard on all models of this category (important note. If it has electric start make sure it also has a kicker incase your battery dies)
Bikes in this category
KTM EXC, Enduro
Kawasaki KLX, KLR
Honda CRF-L, XR-L, CRF-M
Suzuki DR, DR-Z(larger engine sizes)
Yamaha WR-X, WR-R, XT, TW
Fun Bikes: These are the bikes you learn on and go riding with your friends and realize you want what your friend is riding.
Bikes in this category
KTM Don't make play bikes apparently
Kawasaki KLX(smaller engine sizes)
Honda CRF-F
Suzuki DR-Z(smaller engine sizes)
Also a note about 2 strokes and 4 strokes. In case you didn't know or someone didn't explain it to you, a 2 stroke is roughly twice as powerful as a 4 stroke just due to simple mathematics. They don't deliver power the same way and maintenance etc is different but a 125 2 stroke is comparable to a 250 four stroke and a 250 2 stroke is comparable to a 500 4 stroke (although 4 strokes usually are 450s)
So a 125 four stroke is much to small for most adults.
a 125 2 stroke can be used by adults for serious trail rides.
You can identify Honda 2 strokes by having a model of simply CR whereas 4 stroke will be CRF
Kawasaki 2 strokes are KD designated and 4 stroke is KL and I think for the racing engine its KR (not sure about that)
Also you can identify any 2stroke by the exhaust pipe.
But as you start looking more and more at the bikes you'll learn quick whats important to look at to identify them quick.
