[Bweighmaster]

Be sure it's a documented bike , ask for maintenance records , Look carefully to be sure the engine has original bolts / screws in cases , look for gasket sealant ..... Top to bottom tires , spokes , rims , Check everything ...,

 

[Bweighmaster]

How would you recognize original screws on the engine? I only know the one about looking at the oil for shiny metal and starting it for coolant leaks. (Aside from checking/listening brakes, leaks in lines, clutch/brake lever tension and hearing if an engine starts quickly from a cold start and keeps running smoothly.)

I wasn't aware that screws could be identifiers unless they are obviously replaced by a wrong
one.

That's one way , look for wrench marks ... look at case fitment ..., stripped heads ,

 

[Bweighmaster]

Your time will come , But , now you know what to look for ....,