Ok I have got the motor out and got the side cases off and the jug off. One good thing is I found out just as the guy said that I bought it from, that the key sheared off of the counter balance, as I can spin the gear but the balancers stay in place. But I noticed in the oil and inside the case some metal which I don't know if it would have come from the key or what? Anyway the jug looks great and no scratches or pitting and the piston looks good to but I noticed on top of the piston it says 0.75mm and under that it says 571p3 then under that it has cd then an arrow under that. So question is this a stock piston and bore? or over sized? the cylinder wall looks pretty thick but also looks to be ported or something I just dont know and this all might be stupid questions but I am so new to this. Also should I just have the whole motor rebuilt top and bottom or should everything be ok since no scratching or pitting along with a good looking piston. I will take some pics of everything tomorrow when I get some batteries for my camera so maybe someone can tell me more. Also does all counter balancers fit the same bike or is it year by year so I know what to order. I thank you all for all the help you have already given me I also got ahold of metaltech and he is going to do my a-arms for me so thanks again this site is awsome with alot of good people on it, I'm so glad I found it 

Ok heres the piston what size is it, and what should I go with next.

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