Scootertronics offers many ways to upgrade your 49cc two or four stroke scooter. Both types of scooters can have many upgrades to suit exactly what you are looking for from top end speed to bottom end torque or both.
The info below is for a general understanding only.
When doing upgrades to your two stroke scooter whether it be flat-out racing or simple street ridding and commutes a quality cylinder can be added to boast to 70cc. This will do the engine fine if power needed is for street or if doing race package a crank shaft as well as final drive gears can be added. The type of cylinder kit whether it be iron cast or aluminum also matters. The aluminum will run cooler thus keeping power up through long rides. An iron is great for everyday street long as a quality one is chosen. The aluminum kits are not much more cost than a good quality iron from Polini or Malossi. Now of course you can always get the highest cost for the very best quality.
Now you have to get more air and gas into your cylinder kit so at least re-jet and air filter is needed. A low-cost carb can be added for plug and play performance. A manual choke will work somewhat better but please consider your whole set up for oil injection and choke. There are plenty of auto choke carbs in the 19mm to 21mm that will do the job nicely and stock cables can be used. When upgrading to manual choke you cab get a better performing carb with easier starting but cables and oil injection have to be considered. Dellorto makes carbs ofr Stage 6, Malossi and Polini in the 19mm – 21mm size, these are perfect for manual choke. Of course you can go much bigger with a larger in physical size flatslide, PWK carb which are mainly for racing and you have to get larger intake. The smaller in physical size 19mm -21mm with some 17.5 carbs can use the stock intake with adding new reed valve cage and reed petals, which should be done to all scooters no matter what mods are done. Your intake matters plus oil is sometimes injected here and can also be added to inject here if needed.
Air filters come in all different sizes and shapes. The main thing here for me is air control and back pressure. Many an air filter kills the back pressure which kills the gas intake for vacuum. Then you must be aware that space in scooter is needed. So consider space and air flow. There are dual layer filters from Uni and Stage 6 that will keep the back pressure where it needs to be.The K&N free flow is also a good choice but it has to be the K&N brand (35mm). The 35mm air filters fit on most 17.5 – 21mm Delorto and Arrechee carbs. The larger flatslide and PWK carbs will need 42mm – 50mm but please consider space you have on your scooter.
Air in Air out is way for power. The exhaust is important and many an upgrade is spoiled by a 50cc stock exhaust. Although some stock pipes are very good with a 70 kit like Kymco, Eton, CPI and Benelli some are awful like any no name chinese. The Stage 6 pipes ,MRP, Tecnigas and HM70 from Leo Vince are on the top of my list as well as Yasuni. Handmade does the trick as well as chrome exhaust do not rust as fast. There is others also from Hebo, Athena with most made in same factory.
Your CVT drive needs a good belt which does not have to be Kevlar but a good brand name and not stock like Bando or fake Gates. The motoforce, Stage 6, Polini, Malossi which is my favorite do a great job. MRP offers quality belts for all scooters also.
The roller weights when doing 70cc upgrades need to be changed to match up with the other parts of the CVT as in the clutch, clutch bell, torque spring and clutch spring. The weights can round or slider weights from Dr Pulley, the slider weights are certainly the best. The CVT drive is highly tunable and a new spring or correct weight fixes so many problems from bogging down to bottom end and top speed.
The variator also plays a certain part with a good ramp plate that’s aggressive and good quality. The variator bushing wears fast so quality is important and not costly. A Naraku or Motoforce does a good job, Polini and Malossi are great quality. All the parts of the front drive including the drive face, ID, star washer and backing plate with sliders need to be upgraded at the same time not just the variator.
The rear clutch which is my favorite part of a scooter to upgrade due to the amount of pure upgrade you get when doing a rear clutch mod correctly. There are some great clutches from Dr Pulley, MRP, Stage 6, Motoforce, Hebo, Polini and Malossi with Dr Pulley and Stage 6 at the top of my list. You must upgrade your bell, not doing this with a clutch you will not get the full result. Clutches are highly tunable to get exactly what you are looking for plus clutch springs can be changed, weights added and spring tension changed. A 70 kit installed with the correct fuel and air with a pipe and strong belt with a clutch mod will pop wheelies and take off with great bottom end torque.
- MASRC at Sandyhook Speedway (masrc.info)
- New Products for 2011 (scootpower.wordpress.com)
- Retro 70 Stage6 (scootpower.wordpress.com)