How much weight can a scooter safely handle? I have the standard issue 125cc Kymco. My wife and I sometimes take it camping (both of us on one scooter). Space is tight, but every time I find a way to pack more efficiently, we find more things that we can’t live without. I have built a rear luggage rack which works great. Now I want to add some side saddle boxes. I have become very good at loading the scooter, but I worry that it will become unsafe at some point.
Well of course if your scooter had been sold in a 1st world country I’d say look in the handbook.
Instead, have a look at the sidewalls of your tires for the maximum load rating. Total the weight of the scooter (gassed up), and your body-weights and cargo. A scooter has the engine in the rear, and the gas tank too. Then you put the passenger back there, and luggage too. You can estimate that you will have around 70% of that weight on the rear tire, so focus on that. Obviously, moving as much of the heavier luggage to the footwell area will get the CoG lower and more forward, which will help with balance and handling. You can adjust air pressures up to the maximum shown on the sidewalls, but be sure and check when they are cold and do not trust the gauge at the gas station. For sure the total of bike, passengers and luggage must not exceed the total max load rating of both tires.
After this you have to look and see that you still have suspension travel left over. Load up fully and with your passenger on board, stand and ‘trampoline’ the scooter. It’s easier to do this noodling along at walking pace. You should not be able to bottom either the front or rear suspension even bouncing hard. If you are still within limits on the tires, you may have to start looking for stiffer struts/springs for your suspension.
IIWY I’d be shopping for a real motorcycle, or a second scooter for the wife, or a small car. Or you could just change your packrat habits. 
In my experience (11 years riding one), the brakes on those scooters are really only good enough for one or two riders. When you increase the weight, you’re increasing the demands on the brakes. In other words, stopping distance increases, so the likelihood of not being able to stop in time to avoid an accident goes up as weight increases. This problem is exacerbated when going downhill. You’ll need to keep the brakes properly maintained, keep your speed down, and keep your guard up if you’re overloading the bike.
Also, as the bike gets older and loses horsepower, you’re likely to have more problems going up steep hills if you’re overloaded.
And yet, the laws of nature seem not to apply when families of four and their dog Sparky ride a 150cc scooter.
or do they?
[quote=“Jack Burton”]And yet, the laws of nature seem not to apply when families of four and their dog Sparky ride a 150cc scooter.
or do they?[/quote]
Yeah, but they burn ghost money, so, you know… it’s OK.
You might consider adding a roof with a luggage rack. Get strong bunji cords to keep everything secured up there.
LOL. I once came across a family on a 125 scooter with what looked like their whole home contents on it. You know how people go traveling at new year with their own cooking pans, blankets and everything? Well, they were doing that on a scooter. They had some racking bolted around the thing to hold all that shit on and all told it was about as big around as a March.
I ran into them at Techi reservoir. They had ridden there from Taoyuan and were planning to go over to Hualian and back home via Taidung and Kaohsiung. No idea how far they got.
Oh, I forgot to mention. The couple must have weighed 100kg each and their kid was a chubby kid of about 40kg at a guess. 
Maybe you need to buy a car.
I just happen to be selling mine. Interested? 
scooters are unsafe just LOOKING at it 
just kidding just kidding !