http://www.hpiracing.com/walkthroughs/engrebuild.htm
1. pull off the head
2. pull off the back plate
3. take out the sleeve, there are 100's of ways of doing this. i take the blunt end of a pare of pliers, and press the sleeve out, then put cloth around one end of the head of the payers, insert the it into the sleeve, the cloth one goes in the slve, and pull, till its out, i can get a vid for u if u want? i can get it to u by tomorrow
4. take a pair of needle nose pliers and pull the con rod of the crank, turn the engine over and it will fall out.
5. take out the wrist pin
6. connect the new piston to the old con rod
7. reinsert wrist pin
8. install the piston back on to the crank
9. insert the slve, it takes a little wiggleing to get the piston to go back into the new slve.
10. line up the slve with the mark on the case
11. reinstall the head
12. re install the back plate,
13 ur done
14. it would be a good idea to seal ur engine with rtv sealant. around the head, carb, and back plate.
This should help you