power?
STANDARD 95hp... its dependant on the state of the engine your doing it to and what cam your chosing. assuming your engine is nearly new, and you get a lairy cam, you can expect somewhere in the region of 140 - 150 hp. but personally i think you'd be better off with twin 40's not 45's. reason is the lack of air speed passing the venturi of your carb. it wont vapourise the fuel properly at low speeds and could idle really bad or even stall if not set up correctly, especially on cold starts. 45's are better on a 2litre, youll prob find a severe lack of torque on a 1.6. as a rule of thumb, theres no point using a carb opening thats much bigger than the inlet port on your head. it will just reduce air speed. and torque as a result. unless... you want to race track your xr in which case you dont care about idling or low speeds cos youll be too busy revving the nuts off it, creating lots of air speed. on a 1.6 the difference between usin a 40 or a 45 is negligable. maybe 5hp if your lucky. you'd barely notice except that the bigger one runs lumpy with no power down the bottom of the rev range.