90 hp stuttering and burping and stalls

[djlay57]

2000hp Yamaha. Idles rough stumbles installs. Compression check was 120, 107, 120. Carbs are redone check for water in fuel and the spark plugs. How do I determine the piston is bad and what's next

[99yam40]

Bore scope to look at top of piston and cylinder wall or pull the head.

Never heard of a 2090hp yamaha 3 cylinder motor