optimax will not plane

[Merlin Alabama]

2005 optimax 175 hp has been running good. Started getting hard to plane Brought in and rested, Found tip on #6 spark plug bent. All plugs were new and correct. He was running cheaper oil and some carbon so I trashed it and had him get good required il Oil is cheap motor is not Pulled head and inspected cylinder. No play in piston up and down Cylinder walls all in spec. I have seen carbon break off and hit tip but in 50 years only a few times in older motors. Question, Can a reed break go into cylinder and cause problem, No marks on piston were anything hit top. Reinstalled head new plug and went out and retested Still cannot get on plane About 300 plus hours on motor All started when he damaged port head stripping threads for [lugs Had head trplaced and cleaned starhpr side Mptpr will idle perfect

 

[Scott Danforth]

a compression test will answer a few things

 

[Merlin Alabama]

Look up death rattle. Mercury in their wisdom hung exhaust tube by 4. 1/4 bolts. They have been known to break off and exhaust tube is loose. Motor will run good but limited power. Raise and lower trim and you may be able to hear it flopping around. Have done two this year. Would not plane off. Repair and runs great