2010 F150AET1X 0.25mm oversize piston Cylinder size

[scottcmb]

As the manual I have on hand at the moment only covers the older F150A and it doesn't specify bore size for an oversized piston assembly ( probably due to the fact that the earlier models dont or ever did have them available).
Can someone out there who has the latest manual please tell me what the "Actual" bore size needs to rebored and honed too, to get the correct "oversize" piston to bore clearance. I dont think just adding 0.25mm to the standard size would be a good idea in my mind, but if someone can give me the Yamaha spec from the manual, that would be reassuring.

Cheers
Scotty

 

[scottcmb]

Also to add that i want this basic info before shelling out $1600US on piston/rod assemblies to see if the job can be achieved...... im just hoping there is some Manufacturers specifications for these pistons that can be quoted.

Cheers
Scotty

 

[99yam40]

back in the old days you measured the pistons and bored the cylinders to make them fit, but with today's precision parts there should be a known amount to bore them. check with the machine shop you are going to use to do the work

 

[tommarvin]

I agree with 99yam40, the machine shop will tell you what size pistons to get, I have heard Wiseco pistons are the best but cost a little more money. We chamfer the intake and exhaust ports on two strokes, so they don't catch a ring, turn the crankshaft its the heart of the engine.

 

[flyingscott]

You really only want to polish the crankshaft. Those motors are dry sump and run needle bearings.I don't know of to many oversize needle bearings for outboards.

 

[tommarvin]

Thank you flyingscott, I just learned about outboard crankshafts