As above..travel light.
First kit to sort should be a basic First Aid kit for whenever a blue rinse or flat capper pulls out in front of you...enough to deal with road rash and maybe an army type field dressing to deal with bigger 'openings'...the usual applies...sprays,tablets,foil blankets,CPR mouth piece and triangular bandage etc etc .
On the safety aspect...if room permits...a small fire extinguisher...if at all....if you can carry a bottle of water then you can carry one of these too?...the reason is say this I have used one in the past to put out a moto with an electrical fault and with the flames close to the petrol tank...again not that common a thing to ever come across...(touch wood)...
I'll be going back to Morocco at the end of October and before I leave I'll take what tools go in my bum bag. Try to work on your moto with these tools as every day maintenance then you'll know what tools you don't need to bring.
I'll be riding with two side panniers only and no top box and the only thing on top of those at this time will be a tarp(the type you can buy in Decathlon for €25)...If there's a break down of any length of time you can shelter from the sun or rain,thus making any repairs less strenuous....(even if you have to stay for along time,e.g. over night...you'll not die but be kept dry at least) These roll into a compact bag and I have used them to great effect before just to eat lunch and relax for an hour or two under the desert sun.
I usually put the majority of my small stuff in a long CIF/JIF plastic detergent bottle with the top cut off. It keeps them from moving about in the bum bag and you can also wrap heaps of duct tape around it thus eliminating the need to bring a large roll. Also pack super glue. This works really well if you get a hole in any radiator hose. Dry it off...fill with super glue and then wrap with duct tape.I can vouch that it works and will let you limp home!!
As stated a clutch cable zip ty'd to the existing and a throttle cable too. Tape the ends up with duct tape to keep the crud out.Again if it snaps not a long job to undertake.
Brake pads will checked and changed if need be and wheel bearings are small enough to stash anywhere. Even if one fails it's only a 30minute job to change them and ride on.
A 12v pump takes the effort out of inflating a tyre and they're small enough nowadays to stash also. Use your side stand to break the bead so that eliminates a special tool for that.
A tyre grip installed on each rim before leaving is a cheap addition too...if you need to limp on with a flat you can do so at a slower speed. Speaking of wheels....fit a new set of dampers in your rear hub before leaving to avoid any issue there.
A front tube will fit the rear too so only one tube IMO is needed.
Chains and sprockets (if made of steel along with a good O ring chain) replaced before you leave means you don't have to think of that. Maybe a front sprocket if you're uneasy about it As stated a few chain links and a split link along with a chain breaker tool ( I clip my split link onto my throttle cable and also paint the clip white with Tippex...this means when it pings off,if and when needed,and as it invariably will you'll be able to find it!!)On that subject...if you mark your main bolts,e.g. sprocket bolts ,brake pins etc with Tippex then when you're standing about eating or chatting you can visually check them with out ever having to wield a spanner at them.
Also take that little box of nuts and bolts as mentioned,and throw a few fuses in for good measure.
Also any farm supply will carry various chains(for use in various harvesters etc) if you don't find a moto shop...might not be the correct width but the pitch should be close enough....again in 40yrs of riding I've never had a chain break.
A tow strap also is essential...doesn't have to be long....I usually use(and have used in the past, a normal moto tie down strap with a hook on each end)tow from foot peg to foot peg to avoid any fighting with the handle bar,i.e.,if you're being towed...from your left foot peg to the tow bikes right hand foot peg....he'll be able to change gear easily and still brake....and you can steer an still brake with no effort required.
A good strip down and grease of all pivot points will indeed ensure that that's not an issue and you're good to go. An oil/filter change with fully synthetic oil would also give peace of mind...along with a washable replacement air filter and can of spray on filter oil. A small tube of grease(like you buy in cycle shops,the same as a toothpaste tube)means you'll be able to grease the air filter seal to plastic air box.
A regulator spare...a second Yamaha Fazer one fits...fit it before you go to make sure it works...remove and it's small enough to stash....The plug from the original......,as I have done on mine,is to fill it with grease and cover with a section of bicycle inner tube to keep it waterproof(zip ty it tight with several zip ty's)....Thanks to the forum this tip was discovered..
If a long journey is planned and there's lots of kms on the engine....why not replace the clutch discs with new ones to eliminate that also?....Even bring new discs if your clutch hasn't too many klicks on it....stash them in the air box?
Most stuff that will stop you and your moto in your tracks has been covered...after that 'Necessity is the Mother of Invention' as they say...and you can put your hand on your heart and not blame yourself for being a donkey head after wards...even more importantly...you can't leave yourself open for endless pub bantering from your buddies for the next 10yrs....which of course,is even worse than a breakdown!!! LOL