I bought an fd r1, but it is runnig 2 cycle and I'm about to switch it, any reason I should not?

 

Could be plenty, could be none. More info.

 

Rotaries burn oil by nature. They could be running premix because the metering oil pump went bad or just as a precautionary inase the pump should fail. It doesn't hurt the car and can only help.

Since you asked this question, I'm going to take the liberty of assuming you don't really know how rotaries work. Check the diagram on howstuffworks.com. As you'll see, it's a triangle shape inside of an oval. There's no way to lubricate the seals at the apexes of the triangle without burning oil in the combustion chamber.

 

I'd contact the previous owner and inquire why they were running premixed... if it was a precautionary measure then you don't HAVE to, but it's still advisable, but like SLOASFK pointed out if the OMP is broken, or disabled, not running premixed would be VERY bad and your fun would end very quickly .