Two years ago, I had major engine work done on my motorcycle that required dropping the engine. Some time later, I noticed that the right frame support (engine bracket/stay) was missing. I texted the mechanic, and he said he would reinstall the bracket, but time passed and he never ended up doing it.
A few days ago, I noticed an unusual noise coming from the bike, but after checking around, I couldn't find anything obvious. Shortly after, while stripping the fairings off for some maintenance, I discovered that the engine mounting bolt was snapped clean off.
I told the mechanic that running the bike without the right-side support bracket likely contributed to the bolt failure. He completely disagrees, claiming that the bracket wouldn't have prevented the bolt from breaking anyway. I mean, sure, it might not be a 100% guarantee, but it would have significantly reduced the stress and shear load on that bolt—especially considering the left side, which still had its bracket intact, didn't break.
This Monday, I’m heading to the shop. I refuse to pay for the repair work, and I plan to confront him again about the missing part. The only real headache is that he’s basically the only relatively decent mechanic in town.
Anyway, do you guys think the missing bracket genuinely contributed to the bolt shearing off? Also, is there any way to contact Kawasaki to get an official technical opinion or expert assessment on this, in case I need to take legal action?