so just take the engine apart and have it bored out? Can you use the same piston or do you have to buy a new one? And is there any kits that have all the parts that you will need to replace?
I suggest buying a service manual, They can be had for only $16. by Clymer and purchased at amazon .com or ebay. Read the section on rebuild and if you have the tools needed and understand what is involved then go for it. If not ask someone to help you. The book will give you an understanding of what skills are needed and allow you to make the correct informed decision.
You need to measure the piston and or bore with a "MICROMETER", "MIC" for short, a GOOD caliper will get you close enough to see what size you need.
Most machine shops want the new piston so they can set the clearance when they bore it, and if they say they can finish it to size without the new piston find a different shop, because they don't know what they are doing!!!!
You can do all the other stuff your self, all you need is the manual a torque wrench and I STRONGLY recommend the torque wrench extension for the cylinder base studs.
When I did my rebuild this week, what I did was, Ordered a .010 over bore, just because my cylender wasnt gouged, or messed up, had a machine shop bore and hone, and mine runs fine
took it apart and the piston is in 2. cylinder looks fine and the crankcase is o.k.
next is to get new piston and to bore it? and is there anything else need to get