These types of questions are very hard for me to answer with ANY amount of accuracy. A wild educated guess would be 300 hp. The valve size seems large for a 165 cc runner? The cam is on the small mild side, is it a flat tappet or hyd.roller? What do the heads flow? What intake do you have? Carb size? Dish, flat top, or dome pistons? What type of rings? Etc., etc., etc. As you can see, there are many, many variables involved in answering this question. I'll tell you what, if you want to send me ALL the information you can think of pertaining to your engine I will give it a shot.
Just trying to educate the masses,
Jay Roeder ...professional know it all.
You can also email Jay Roeder at firstname.lastname@example.org