hi kwango
thats right yes i did have a 640 and i had about the same has your self out of the engine and the 115hp weights a lot more than a 90hp thats why the boat with the 90hp is faster but on the bright side the fuel saveing is alot greater with a 115hp and i also had problems with my thottle cables when replaced i could take the engine to 5500revs and still get between 29 and 31 knotts any problems give us a call .
07966 198093
mark b