Let’s put on our detective cap and look at this analytically. I will quote from the OP:
“and after reaching 1,200 miles, I took the bike to a reputable shop known for their expertise in Suzuki motorcycles. The builder there installed a full Brock's AH2 system, a Sprint filter, Moto BT velocity stacks, and tuned the bike accordingly.”
I asked the OP, what exactly was involved with the “tune” and he admitted that he was not qualified to answer that. Besides the velocity stacks, and pipe no other aftermarket items were added. So “tune” meant they got into the ECU.
Next quote:
“Initial Issue with Noise:
began noticing a rattling noise around the radiator when the bike hit 6,000 RPM, in every gear. The noise wouldn't appear while on a bike stand or on concrete, only under load during riding“
Engine noise, only under load could very well mean pre-ignition, AKA as pinging, also known as pre detonation, meaning the fuel air mixture during the compression stroke gets ignited too early, causing a shock wave which becomes very audible. To hear it while riding under load, wearing a helmet, must have been pretty bad. It is very possible that the tuner mistakenly, without intent had a finger problem, or something else, some wrong numbers ended up in the ECU table.
No guess, that the noise the shock waves would cause failure of the crank bearing carrying the majority of the load.
As far as the tuner being an expert, even the best make mistakes sometimes. After all, those who learn from their mistakes, use it as a path to become the best.
About the Suzuki dealership? Suzuki USA do not have a program or a system where techs are qualified, through training, certification, or anything. We have no idea about the skills of who works on the bike.
My guess, is if no one touched this bike, other than just riding it, it would still have been purring along happily.
