l shot my piston #4 on my evinrude 115, l was told that usually #1 goes out because it usually runs the hottest.l am thinking oh having it rebuilt but scared to because if l cant find the cause of the first time why should l fix it again. anyone heard of this happening before. o yeah and l mean it really tore this piston up,.

If it were me, it would totally depend on the cost to rebuild as apposed to the cost of a replacement. We're looking at an 11 or 12 year old engine here, so l am guessing the cost is going to be somwhere close to the same or maybe cheaper to replace.
If it tore the piston up that bad, it may not even be repairable without a whole new power head.
l think it is time to start looking for an engine.

rebuild it yourself for 1/4 the price, make sure your tank contains no impurities such as water,check your impeller for cooling water flow,and it wont happen again,its probably a one off

This is a common problem that has many possible causes. Improper storage of the motor ranks #1. If u use ur boat once a week, & use 50:1 oil in ur tank, u should get good life from the motor. It is when the boat sits for weeks.even months between usages that problems arise.
What happens is that the oil from the fuel, begins to dry out, & the crankshaft bearings, rings, & other moving parts don,t get enough lubrication once the engine is restarted & run hard. This is especially true over the ''winter storage'' . Most people think ''winterizing'' is to keep the engine from freezing, when it is actually mostly a storage procedures.
It is much less expensive to repair than purchase a new engine. But, it has to be done by someone experienced with rebuilds. The major area of concern is not the piston or rings, It is the crankshaft. The heat generated in running to failure, often scores the crank & destroys the bearing surface. l hope this helps u understand the causes of most failures.

It is not the piston it is the sleeve or cylinder Did it grove it much as they can only bore it 40 thousand over> which is not much> Check for cracks in the cylinder wall> And rod bearing on crank>