Hi does anyone know of a good place to start on mods for the cn250 clone without giving up top end?

Start with a stronger torque spring.

I would suggest a white main spring, and 17 gram sliders. that way you still have some top speed and added low end

Jay - what kind of ridding are you planning to do? There are so many mods you can do to this engine, it helps to have a good idea of what type of ridding you want to do.

Most of the riding I will be doing is open field. Some trail but nothing real steep.

then the 17 gram sliders and a yellow malossi main spring would work fine for that type of riding

If you haven't done it yet, get an air cleaner and a main jet. The difference is AMAZING and much healthier for the engine. More power, cooler running, and actually quieter. All for about $30.

Thanks guys I'm going to start this next week.

Any suggestions on the size of the jet?

if you will be running the stock exhaust then start with a 122.5 or 125