F115 Lower Unit Won't Fit

[AKboling]

I bought a 115 lower unit to put on my factory 80 jet, when I went to install the lower unit I discovers the spline count and diameter of the shaft on the lower unit were smaller than the shaft on the jet lower unit. When did Yamaha change the drive shaft in the lower units on the 115's.

[99yam40]

what is the model of your motor and the motor the lower unit you found?
that info might help some

[boscoe99]

I bought a 115 lower unit to put on my factory 80 jet, when I went to install the lower unit I discovers the spline count and diameter of the shaft on the lower unit were smaller than the shaft on the jet lower unit. When did Yamaha change the drive shaft in the lower units on the 115's.

Are we talking about an F115? Your title makes me think so but then in the body of your message you are referring to two stroke models.

All F115TLR/TXR (X) models and all F115LX A models use the same drive shaft. Part number 68V-45501-10-00. The drive shaft turns the oil pump.

With the F115LX B models the drive shaft part number changed. The crank shaft now turns the oil pump.

The jet pump drive shaft is not a Yamaha part by the way. It is made by the jet pump maker.

[AKboling]

To clarify my motor is a 2016 F115JB and the lower unit off the donor motor is equivalent to a F115LA, I finally got in touch with my local service guy and he confirmed the drive shafts are different on the B models. So I need a F115LB lower unit to work with my motor. The B series motors have a larger diameter shaft with only one set of splines as you mentioned because the shaft no longer runs the oil pump. In other words I'm screwed, $2000 for a new one and there aren't any used ones around.