I have a v6 yamaha block it had nothing wrong but a cracked head due a casting defect. I was told is a 4.2 block Click image for larger version. 

Name:	yamablock.jpg 
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ID:	373140Click image for larger version. 

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ID:	373141Click image for larger version. 

Name:	yamablock.jpg 
Views:	36 
Size:	87.4 KB 
ID:	373140Click image for larger version. 

Name:	yamahablockk.jpg 
Views:	45 
Size:	96.2 KB 
ID:	373141