The notorious stock Allen head bolts are known to be a PITA and strip easily.
An excellent and easy replacement is the bolts that connect the fuel tank main bracket to the fuel tank (blue/plastic). They are exactly the same size, have a normal 8mm hex head, and have the same coating on them (phosphate?) which should help prevent any galvanic corrosion from metal/finish incompatibility (it can be risky to use any old bolt from the hardware store).
BOLT, FLANGE 95027-06016-00
I know Brain/totallyttrs sells alternative bolts also but the tank bolts are easier for me to get here in the US and the same coating on them make me more comfortable as well, if only for looks.
Edit:
This same bolt seems to be used on the rear caliper to hold the plastic cover. Some places list the part number above as being be superseded by Yamaha part 90105-06696-00. Not sure what the difference is.
-- Edited by Sprok on Wednesday 10th of February 2016 08:52:29 PM
Got the new Yamaha bolts. Here it is compared to the original:
Nice, yeah?
Again, I'd like to point out that stainless steel bolts are probably not a good idea. Especially under the elevated temperature on the motor, add some water, then you will get galvanic corrosion between the steel and the aluminum with the aluminum acting as the anode (therefore it will corrode). I'd rather have my bolts corrode than my engine case!
-- Edited by Sprok on Thursday 3rd of March 2016 09:45:33 PM