så get i startet on my 550 k3 78"
i get this 550 theap korse noises in engine,,its the cam thain eating the engine blok,,så nev tensioner and chain,,and nev pistons and over bore..
one of pistons are velvet 

 dovn.in top,,see pic,,and piston ring are broke..
pistons are marked B-374  honda (6or 5),,and mess 58.5 mm is this smallest boring ???in danish mean "boring" diameter 

 on cylender