Stream fisher and i have been working on his 9.9 and we have been pretty successful until now. We performed a compression test and got 120 psi on the top and 155 psi on the bottom so we were going to inspect the pistons. We have removed the head and the tops of the pistons are black and have carbon deposits built up. We then removed the six bolts holding the powerhead to the exhaust housing. But this has proved to be a problem, the powerhead and the exhaust housing are inseparable. Please help