Okay so this was my first tear down and rebuild so here is my experiances Hopefully someone can learn from them.
1.Clean your bike before you tear it apart. Then when the plastic, seat, and tank is off clean it again. Finally when you pull your motor out clean the motor again. Then when the motor is tour down clean it again. If you think its clean do it again. When you put everything back together do it on a white cloth or paper so you can see any dirt that may be around.
2.Go through a manual for the bike your working on before you tear down the motor. Make sure you have the manual for the bike you are tearing down. This was a major tool for the 65sx I took apart.
3.Make sure you have an impact gun. Lock thread sucks to break loose without an impact gun.
4.Make sure all the parts you ordered are correct. Also read their directions for each part when you put them together. (See #7)
5.Changing the crank bearings. Yeah its simple as everyone says. Turn your case over heat it up around the bearing with a torch and tap out the old one. Next stick the bearings in the freezer for an hour or so (Colder the better) then heat your case in the oven or with a torch. (KTM manual says 150 degrees) then take the cold bearing and drop it in. Literally it should fall in! (Its kinda cool)
Also check your ports that provide oil to the bearing. Mine had a little flaw in the casting that may have helped my bearing seize. I bored out the piece of metal to make sure it gets good flow.
6.Crank tools......Just because you spend the money on it doesn't mean its going to work. Cranks come with different threads and you need to make sure you have the right one to put on your crank. If you do not have the right nut check and see if the nut that was on it will work with your puller. If not stick your crank in the freezer. Next you can heat your bearing (make sure you don't burn your seals) make sure when you heat the bearing you do the ball bearings as well as the race or the ball bearings can expand and put divits in the race. When the bearing is hot take the crank out of the freezer and put it though the bearing. It should slide right on.
7.Sticking a piston in a bike sounds simple right? Make sure its going in the right direction, also make sure you don't have to drill holes in the piston skirt(Read the directions)
8. Watch for thrust washers and make sure you put them in the order they will go back in.
9. Make sure and read the manual it will help make things easier. (Tranny was a bastard until I read how to do it.
Then it took 5 minutes)
10. Put some oil on all the bearings before putting parts together. Makes it go easier and gives them some lube for start up.
11. When you mark your mag. Do it with a punch or something that doesn't whipe off. I did it with a marker and then the cleaner I was using washed it off.
Luckily the screws made good marks so I was able to get it back in the right place.
If I can think of anything else I will add it on here so hopefully it will help someone else.
1.Clean your bike before you tear it apart. Then when the plastic, seat, and tank is off clean it again. Finally when you pull your motor out clean the motor again. Then when the motor is tour down clean it again. If you think its clean do it again. When you put everything back together do it on a white cloth or paper so you can see any dirt that may be around.
2.Go through a manual for the bike your working on before you tear down the motor. Make sure you have the manual for the bike you are tearing down. This was a major tool for the 65sx I took apart.
3.Make sure you have an impact gun. Lock thread sucks to break loose without an impact gun.
4.Make sure all the parts you ordered are correct. Also read their directions for each part when you put them together. (See #7)
5.Changing the crank bearings. Yeah its simple as everyone says. Turn your case over heat it up around the bearing with a torch and tap out the old one. Next stick the bearings in the freezer for an hour or so (Colder the better) then heat your case in the oven or with a torch. (KTM manual says 150 degrees) then take the cold bearing and drop it in. Literally it should fall in! (Its kinda cool)
Also check your ports that provide oil to the bearing. Mine had a little flaw in the casting that may have helped my bearing seize. I bored out the piece of metal to make sure it gets good flow.6.Crank tools......Just because you spend the money on it doesn't mean its going to work. Cranks come with different threads and you need to make sure you have the right one to put on your crank. If you do not have the right nut check and see if the nut that was on it will work with your puller. If not stick your crank in the freezer. Next you can heat your bearing (make sure you don't burn your seals) make sure when you heat the bearing you do the ball bearings as well as the race or the ball bearings can expand and put divits in the race. When the bearing is hot take the crank out of the freezer and put it though the bearing. It should slide right on.
7.Sticking a piston in a bike sounds simple right? Make sure its going in the right direction, also make sure you don't have to drill holes in the piston skirt(Read the directions)
8. Watch for thrust washers and make sure you put them in the order they will go back in.
9. Make sure and read the manual it will help make things easier. (Tranny was a bastard until I read how to do it.
Then it took 5 minutes)10. Put some oil on all the bearings before putting parts together. Makes it go easier and gives them some lube for start up.
11. When you mark your mag. Do it with a punch or something that doesn't whipe off. I did it with a marker and then the cleaner I was using washed it off.
Luckily the screws made good marks so I was able to get it back in the right place.If I can think of anything else I will add it on here so hopefully it will help someone else.
Now that I think of it, I have not needed to take apart an engine for many years. 
