So far this has been an impressive motor. We have a bone stock 800 Axys and a BMP Stage 3 800 Axys. Both motors are running strong with zero problems. The motor seems to like modification as well. We ran the 2nd one through all the paces on the Dyno and its rode hard every time were out. The race crank really helps it spool up quickly and is stronger than the old stock Pro crank. The previous 800 motors from 2013 were better than previous models and this one is better yet.
-Easier throttle pull by having electric oil pump
-3 D mapping on exh valves with less maintenance
-Improved pistons
-improved cooling and faster warm ups
-no local dealers reporting problems with motors
-lower quick drive ratio is actually easier on the motor and clutching than last Pro's making it run cooler with less effort (strain) on motor.
-easy weight reduction with aftermarket muffler and battery (elec start)
What more can you ask for?!
Better water proof electrical connections is all I can think of for the motor even though I haven't personally had any problems with them. As Jaynnelson suggested add a little dielectric grease to the inside of the connections.
As far as other codes go, this motor really likes to rev quickly (lite weight crank), make Sure you have enough clutch weight to keep from setting off codes. It happens so fast you won't even notice it over rev'ed anytime the track gets loose (jumping, loose snow, icy hill etc).
Parting thoughts: Stock Axys motor has noticeably more power and is a "fun" improvement over previous Pro's.
Adding quick and easy (Any back yard yahoo like me can bolt a pipe on) Mod's like I did turn this into an adrenaline junky's best friend. It flat out rips with some simple Mods that you can easily add more stages as your budget allows.