760 Crankshaft differences?

[MTRHEAD]

Yamaha 760 64x crankshaft out of a 1996 WB2

Never seen one with holes in bottom of rods versus slots. I’ve seen maybe 100+ Yamaha oem cranks. This is a first. My guess very early 760 crank? I’m guessing this was done for strength and they reverted back to traditional slots for some reason. I did an eBay search on cranks forsale and I did find a couple like this. I have bought 64x rods before and they have slots and I own other cranks from 760’s and they have slots

Thought about why:
-for strength and it was a special rod mfg process versus the standard process thus costing extra money to make. Stopped it for $ savings?
-proved out to be an issue with lack of lubrication? (If mixture wasn’t perfect)

Anyone know the story? (This one is like brand new)

 

[MTRHEAD]

My guess would be the slots are cheaper:
#1 Huge volume
#2 Fast broach or horizontal fixture mill

My guess drilled would be much more expensive
#1 extremely low volume
#2 Drill, with fixturing and consumables vs. broach/Horizontal mill

 

[Storbeck]

Are the slots milled? These rods are forged aren't they, seems like that feature could be just created right in the forging. Hole could not, so hole probably more expensive. (?) speculation on my part.

 

[MTRHEAD]

Are the slots milled? These rods are forged aren't they, seems like that feature could be just created right in the forging. Hole could not, so hole probably more expensive. (?) speculation on my part.

This is the slot on every Yamaha twin crankshaft I've ever seen until this weekend.

 

[Storbeck]

Ah I'm an idiot I was thinking of the notches on the sides.

 

[kevbo]

There was an early part number from the first year or two. Ive got one of those early round holed ones still NIB. I dont know why they changed the rods but it seems like the old ones have withstood the test of time.

 

[TheBuzzard]

Forged rods don't have numbers

Are the slots milled? These rods are forged aren't they, seems like that feature could be just created right in the forging. Hole could not, so hole probably more expensive. (?) speculation on my part.

Cast parts have #s cast in there. Forged parts are stamped