for your weight a 125 would suit you fine as for height there is not really a difference between a 125 and a 250. its a big difference between power from a 125 and 250. but if you think you can handle it you'll be able to jump stuff easier with the 250. there is more maintenence involved with a 2-stroke compared to a 4-stroke. and the newer racing 4-strokes are just as good as a 2-stroke. i find that they are easier to ride, also there is craploads of low-end power compared to a 2-stroke so it's easier to stay on the power. as four 2-strokes blowing up i've never had any problems with that. the only thing is if you don't premix right you might seize the motor. if you are getting an aluminum frame cr try and get a newer one. i've heard that the older ones vibrate alot.

i have a 2000 Rm125 if your interested

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