Design upgrades to your 49cc two stroke there are a few musts you need to consider when choosing parts.
Type of engine in your scooter
There are about a half dozen brands of scooters using two stroke engines sold in the USA. Some more than others but no reason to leave any out.
The Yamaha Zuma is the most popular two stroke scooter sold in the USA that uses the Mineralli designed engine. Also known as Jog 50. This is the most common type of engine for scooters in the USA.
These are the specs that are most important
Piston uses a 10mm Wrist Pin
Crank as a 13mm taper for variator
15X12 variator weights
Exhaust port is not the same as other two stroke engines
Clutch stock is 105mm as well as bell always buy a matching bell for your clutch unless using stock
Variator upgrades sometimes move to 16X13
Some scooters made in Tawian also use the Mineralli engine plus same as Yamaha Zuma they use a 10mm wrist pin for piston these are the most common brands Eton, Adley, some Aprillia plus one Chinese brand I know Baccio
The second most popular scooter engines in the Franco Morini design used in TGB scooters and Hyosung and some Aprillia and Itla Dragster
Uses 10mm wrist pin
Biggest difference here is exhaust port hook up is different than Mineralli
Now for all of those with Chinese brand scooters don’t fell left out at all the Chinese did a good thing and copied the Mineralli engine but instead of copying the Jog 50 they copied the Jog 90 which makes it somewhat different in specs plus a little more robust, this is what I started calling in 2003 the 40QMB engine
Chinese brand uses the 40QMB engine
12mm Wrist Pin
16mm Taper on crank for variator
Stock clutch is 112mm as well as bell MK II Clutch and CNC Bell Best Buy
15X12 Variator Weights
The same cylinder can be used on all mineralli but piston must have correct wrist pin.
CPI which is from Tawian also uses 12mm wrist pin and 16mm taper
Piaggio using their own brand of engines for their scooter such as the Zip model.
Vespa also uses these engines in their LX models and then there is vintage models.
Kymco uses their own designed engine with a 12mm wrist pin plus a CVT that uses 16X13 weights 105mm Clutch and Bell and 743 20 30 Malossi Belt, the Kymco scooters benifit very much from a Malossi Iron Kit with a MK II clutch from Stage6 at 107mm with the CNC Stage 6 Bell or a winged bell also from my experience its better to run 7gram weights and tune the CVT through the torque spring and clutch springs, running a 2000rpm spring and 7gram Slider weights will keep the top end plus give you perfect take off in traffic.
Discount code is kymco10 for 10 percent off your Kymco scooter parts order of 100 dollars or more