2013/09/13 tzm150 millenium england uk

i have a tzm 150 in the uk england,its a millenium model 1 of 150 brass clocks stating 240kph here is the problem
took the barrel off to reveal the piston,it had stated on the top 2.5 the previous owner thought it was a tzr125 so i got the standard bore dimension which was 56.4 i added the 2.5 ovesize and it adds up too 58.9,is this why it wont go past 7k-8k revs,servo works fine i found out the std bore for tam150 is 59 so the piston i had in the bike was point 1 of a mm off standard size any help would be appreciated...  
i have a vid of it running on youtube

It quite sometimes I didn't post in this forum.
Do you still need help? Because your posting was in 2013.
any way feel free to email me at jasmie22@gmail.com