87 Yamaha G2 Engine swap

[keith4128]

I want to ask all of you experienced engine swappers out there what is the preferred engine to use on an 87 G2, I just got this thing and the engine started blowing lots of blue smoke. I want to have more power and torque to be used around the farm and also taken with us on the as we go to different campsites that allow carts. I was looking at the Predator Hemi, and Duromax 16 and 18HP, with electric start. I am curious if I can use the original Primary clutch on any of these engines, do you recomend that I remove the governor? Is there enough shaft to use the original generator pulley, or do I need to add another coil for charging (if that is possible). What are your opinions of some of the performance kits that are available? Any advice on this matter is greatly appreciated, I have not started dismantling any of my kart yet, so I don't even know what the stock shaft size is yet.
Thanks