Okay, so admittedly this is not a Motorcycle engine. It doesn't have four cylinders, and it's not even an Overhead Cam. BUT, it does go to show a good sense of what can happen if you don't put your engine together right.
The picture below is from my Lawn tractor. It was given to me for free from my Dad who had replaced the head gasket (and that's all he did and I never touched it - it's not our fault.
). Apparently whomeven had the engine apart the last time didn't torque down the connecting rod bolts properly and they worked themselves loose. As you can see by the picture, a connecting rod can only take so much abuse from this kind of situation:
If you look closely in the picture you can see the bolts on the bottom of the rods are loose. This is how I fished them out of the case. I haven't touched them.
A lot of people on this board are super smart and know what they are doing and we all turn to them for advice (TwoTired, MRieck, to name a couple - Thanks, Guys!!) and a lot of us are amateurs trying our hands at wrenching for the first time. This gives an idea of what can happen if the right steps aren't taken. Take your time and do it right, all.
Now, I've got to go see if I can find a connecting rod for a Briggs & Stratton engine. Shouldn't be too hard, right?