We suggest that all Performance Parts be “matched” and for that reason, we have selected the AIRSAL, MALOSSI, MOTORIO, TECHNIGAS and TECNOMOTO line of superior products. The following information may be of benefit in understanding and deciding on a course of action tailored to your needs.

All restricted motors are usually governed by a spacer between the front pulleys, restrictors in the exhausts (sometimes) at the exhaust flange or rear stinger outlet and by a rev limiter built into the CDI units. On some motors, disconnecting one wire disables the rev limiter. On newer models there has been an increase in the proliferation of manufacturers and technology which generally means the original CDI unit must be replaced. These replacement CDI units can have the standard ignition timing or variable ignition timing with no rev limiter (which is useful when seeking higher states of tune). Some of the newer machines are being further limited with the addition of catalyzed exhausts with a blocked “resonator” tube coming off the lead pipe of the exhaust.

Some of the problems encountered with these style engines are that the RPM varies greatly as the pulleys change diameter, this can be due to the variator internal ramp angle or that the standard transmission spring cannot cope with higher 70cc power output without the belt slipping at lower speeds. The easiest way to cure both these problems is to use an aftermarket variator and rear pulley spring to enhance transmission performance. The rear half of the rear pulley can be changed so that RPM change is reduced to a minimum as the pulleys change diameter. The rear pulley half is known as a torque driver pulley.

The excellent quality of many of today's popular cylinders with TECNIGAS expansion chambers can further benefit by suing a race/fast-road transmission setup. To do this, you wold install a matched rear pulley assembly, variator and special drive belt. The only extra part required is a clutch assembly to obtain a complete race transmission system. MALOSSI has named this the OVERANGE SYSTEM. The pulley diameters are larger allowing a lower belt position at the beginning and ending with a higher final drive ration. To accommodate the extended travel of the larger pulley diameters the electric starter mechanism usually needs to be removed.

If an exhaust is used with a cylinder that between them generates a wider power band, then the only transmission part required is an upgraded rear spring so that the belt slip is eliminated.

One of the most popular aftermarket exhausts are those supplied by TECNIGAS in several different styles. All are hand made in Spain and give 25/30% power increase on air cooled and up to 35% on water cooled motors. These come with rollers so that the transmission works in the right range. The TECNIGAS exhausts are very well made, improving both top speed and acceleration. Certain models such as the Yamaha Zuma required stronger clutch springs to raise the engagement speed for the exhaust to work properly. TECNIGAS NEXT R exhausts are generally designed to increase the peak engine speed by 1500-1800 rpm. The TECNIGAS RS 70 will yield rpm or better depending on the cylinder and carburetor used.

Clutches are available in two and three shoe types. Again, springs are used to alter the biting point when tuning the transmission. On higher states of tune where enough slip cannot be generated by the springs, aftermarket clutches are available that have a choice of springs and lighter shoes to give more adjustment. The ultimate clutches are POLINI 2G Clutch and the MALOSSI Delta clutch. These both have a choice of springs, spring positions and moveable weights to allow the clutch to work with any motor from standard to full race. The common sizes used in the US are the 105mm (YAMAHA), 108mm (KYMCO) and 112mm (ETON). Depending on the bikes country of origin and despite the fact that they share similar engines you must always confirm your existing size.

Cylinder kits are available in several formats, basically cast-iron with or without cylinder heads, road aluminum with cylinder head and race aluminum with cylinder head. Aluminum is always going to be the best for heat dissipation and features a nicasil plating. Cast iron is still popular mainly due to the materials lower cost. Cast iron naturally takes longer to get to its operating temperature so there is always the issue of the piston expanding faster than the cylinder resulting in what is called a cold seize. As with any engine proper warm up is necessary for long life.

Most engine units use an oil injection pump which is connected to the throttle. That makes oil delivery dependent on cable adjustment only. When working with tuned motors you must use fully synthetic two-stroke oil to avoid problems with lubrication and, if MALOSSI race cylinders are used, either add extra oil in the gas or remove the oil injection valve and use oil at a 3% mixture with the gas. We recommend KLOTZ SPECIAL FORUMULA oil products.

Carbs come in many different sizes – the standard factory size can range from as small as 12mm up to 18mm. For road use 17.5mm is large enough but many of the AIRSAL or MALOSSI aluminum cylinder kits with expansion chambers will benefit from larger carbs – from 19mm to 22mm are popular sizes. Some motors have auto chokes and others manual cable chokes – carbs can be supplied with either. Noted makers of performance carbs are ARRECHE, OKO and DELORTTO.

To raise the overall gearing there are several types of gear kits available with different numbers of teeth to suit various models. The best option is to use the gear kit recommended by the kit manufacturer and obtain a matched balance between power and gearing. If the gearing selected is too high then initial off the line or overall performance suffers noticeably. TECNOMOTO, MALOSSI and POLINI offer many primary and secondary gear kits.

Scooter racing is a very popular sport in Europe – particularly Italy and Spain. This popularity has produced a large market for special cylinders, crankshafts and transmission parts. Operating RPM’s are between 13,000 and 14,000rpm and, although very powerful, the wear rate for ordinary road and personal use is not acceptable. The life of some components in race use is as little as 10 hours and a full engine rebuild of crankshaft and bearings can be required as often as every 25 hours to ensure reliability.