Why did you use a 10mm wrench?
I believe that Harleys use American wrenches. If I don't have the right size, then I use an adjustable monkey wrench.
What? Are you being serious? You think or you know? There is only 2 answers to that... I assume you meant "American standard" and not wrenches in general, they come in many different shapes and sizes (Flare, Box, Open, Crescent, Crow, adjustable, etc). The Hex bolt heads are all metric (4mm and 5mm I've used repeatedly), put a standard size in there and you will round it out internally. Almost everything is Metric, most manufacturers stopped making/using Imperial (American standard/fractions) many years ago. Every recent (last 15 years) car, truck, and motorcycle I have worked on has all been of metric standard, not Imperial...
And you use a "race car wrench" that's not feasible at all... Slip and round and strip bolt heads doing that craziness... No one in their right mind that works professionally on anything uses as their first go to tool. Now as a back up, or for off sizes or tight spaces then yes, I have used it before... That's like telling someone to use Vise grips on every single bolt, nut, and head on the car... You can do it sure, but is it right? Definitely not...
Just like on welding tanks and Torch tanks, I have exact fit wrenches for the job. Now I have seen guys use race car wrenches and destroy brass heads like nothing, but they don't care... Well I want a clear conscience to sleep at night knowing I did the job right, from my professional experience and knowledge, and the right tools. That's them, not me...
2001 Kawasaki ZX-6R Ninja (RIP)
2016 Harley Davidson Street 750 (modded)
1998 Eagle Talon TSi AWD (10 sec baby)
2001 Pontiac Grand Prix GTP (High 12 tugboat)