slmjim+Z1BEBE wrote: Never ride a bike on which the road-worthiness has not been confirmed by you or someone mechanically qualified that you trust. Even if the PO "promised" the bike has been "serviced" and is ready to ride, there is no substitute for performing due diligence as to safety & readiness. Brakes first, always; before you make it go, make sure it'll stop. There's no telling what some past Bubba has done that may be hidden from sight. Your brother was fortunate.
MGK612 wrote: ... the front sprocket fell off ...
Judging from the condition of the teeth on the rear sprocket, the entire final drive system ( chain and sprockets ) was likely far past service life. Was the chain checked for "stretch" prior to riding the bike?
... check to see if the output shaft was bent/moved up and down ... A small amount of fore/aft movement ...
There should be essentially zero slop in the output shaft. Running a chain too tight will damage the output shaft and/or bearing, leading to radial play. While the motor is out during frame repair, we suggest the output shaft and bearing be checked for damage.
My concern lies with the frame...
Indeed. Your concern is well founded.
How should I go about button up the frame/swing arm?...
A welder who understands frame welding and the effects of welding heat on frame strength should be involved in this patch.
Good Ridin'
slmjim & Z1BEBE
Thanks for the concern slmjim!
But my brother was well aware of what he was getting into, rides his 2017 Speed Triple virtually everyday, and checked it over (including chain tension) and of course rode it before telling me it was good to purchase.
After my brother-in-law welds up the frame, I am going to have a shop put on the sprockets and chain and do a service check on the whole bike. I've seen YouTube videos where guys talk about the output shaft sometimes going bad on the KZ1000s due to a lack of proper maintenance. So, I will be curious to see what the shop says as well. Hopefully all is well.
Thanks again for your concern and comments!!