Usually when they break a tooth off, it breaks the case right behind
the pinion retainer nut and that usually make the case a moot point.

the biggest issue with them is the upper gears pitting out



Like this

They pit like that behind 525's. That is the biggest issue with them and why I don't see a SC as much better. With smaller power like a 525 I have known people build the XZ drives out of the XR. Gyno the gears and they hold up pretty nice.
As soon as you see the flakes when you change the drive oil its time to pull them apart or its a time bomb.

I’ve witnessed 500EFI’s break teeth off…..BOOOM… oil slick and a long, hot ride home.

Spent the evening on my 16' Donzi.

Realized as we were idling out that I spent less on that boat, trailer, and motor than I spent today on new gears, clutches and bearings to rebuild the XR. It's interesting math considering I have as much fun on the Donzi as the CIG.​​​​​​​

Curiously what's the various forms of bravo drive ratted for(HP/torque) from stock onwards?

thx

I assume Merc has never put them behind anything beyond their 525's.

Does anyone know what's mated to the 565's?

Either way I don't think Mercury is going to answer a warranty call from me on 14 year old XR's behind 800hp.

They put them behind SCI 600's,,,,, and everything now till you get to the 700's. Nuts.

These are snips from a 2012 Mercury product handbook I have saved on my PC as a PDF.

The left out the disclaimer, "Your mileage may vary."

Yeah, there is probably very small print claiming no warranty at that power on the XR.

Mercury racing current site still says 600SCI standard with Bravo XR, quote below.
Under each engine they list compatible drives.
Interesting the 700SCI have M6 and M8, whereas they used to have the NXT.
Maybe they don't produce the NXT anymore.