08 superjet engine engraving on exhaust ports?

[Dave Geiger]

I recently bought this 08 superjet and I noticed the numbers 16 and 12 engraved in motor. Guy claimed motor was never touched, and have no idea about why the numbers are there. It was a one owner ski......has anyone seen this before? Any ideas why they would have numbers scribed in then?

 

[Mdavies_02]

Not sure.

But you could use these

http://www.x-h2o.com/index.php?thre...issers-hoses-waterline-parts-fittings.101341/

 

[shepster]

It's just a way yamaha maked the cylinders and how well the ports matched up, 00 being the best

 

[Yamaha785]

I have a 11 and a 08 both have numbers on them. Not sure the meaning though

 

[Scraggly]

I've been told it's sleeve to casting alignment. A reference for qc at Yamaha

 

[Matt_E]

It's just a way yamaha maked the cylinders and how well the ports matched up, 00 being the best

That's certainly a popular explanation because it assigns some imaginary value to 0 0 cylinders. Thing is, why would Yamaha care at all how well the ports line up?

It's been discussed in the past. A far more likely explanation is that the numbers signify a clearance measurement indicating which OEM piston and ring set to use to get factory spec clearances. Because that actually DOES make sense from the manufacturer's point of view.

 

[TheBuzzard]

that is the port alignment #s and thats been known from the beginning of time. quality controll is why yamaha would want to know. some are probably out of spec when they get inspected and have to be fixed. you cant just stuff a sleeve in there any old way and call it good. real companies that last, do quality controll.