These motors have been around for nearly 10 years now and have evolved into extremely reliable engine units. They can be divided into two basic types: air-cooled and water-cooled. The air-cooled and water-cooled motors can be treated similarly when it comes to boosting power output but the water-cooled motors have a better starting point - they generally have a better exhaust system as standard and have no drag from the cooling fan.

The basic 50 motors use cast iron air or water cooled cylinders on the same crankshaft and case assemblies. They come with a variety of wheel sizes fitted: 100/80/10, 120/90/10, 130/60/13, or 120/70/12, depending on the styling used on the machine. Some of the large Raleigh Runabout styled machines use 16" or 14" wheels with narrow tyres. This variation in tyre sizes leads to two different crankcase lengths with approximately 2" difference, and the internal gearing is adjusted for the power output and wheel sizes. The transmission is basically the same, the belt just being longer to accommodate the increased crankcase length.

The 80cc motor is air-cooled only and uses the same crankcase lengths, but the stroke of the crankshaft is 44mm not 39.3mm and the air-cooled cylinder is aluminium with Nicosil coating at a bore of 46.5mm. It is possible to fit the 80 crank cylinder into the 50 case and vise versa, but the differences in stroke mean that the crank and the cylinder must be used together.

There have been a lot of updates over the years. Although almost all parts are interchangeable it is not always possible without changing something else as well. It is important with the gearbox parts to ensure that everything is compatible - gears with the same number of teeth don’t necessarily have the same profile.

The usual first step to tuning these motors is to fully derestrict them. On the air-cooled motor fit a better exhaust, usually LeoVinci, Arrow, Polini or Malossi. Don’t change the exhaust on the water-cooled motors until later in the tuning process. The price needed to improve the performance of the standard water-cooled exhaust can just about buy a 70 kit. A 70 kit with standard water-cooled exhaust gives better performance than a 50 with an aftermarket exhaust. On the air-cooled engines change the exhaust first (not ET2, because it has a semi-reasonable starting point) then fit the cylinder kit followed by a gear kit and then a carb kit.

The choice of where to go from here needs to be looked at before the cylinder is bought. The cylinders are available in road cast iron, fast road aluminium and race. If more than 60 or 70 mph is required or a larger boost in acceleration is needed then power is the only way to achieve this, and the better cylinders, carbs and transmission components become essential. As you get nearer the race power outputs and engine rpm then the crankshaft will need changing to cope with the increased power.

It is possible to get storming performance from the water-cooled motors in race or near-race tune, but the building and maintenance can be expensive if the enthusiasm to increase the power output is not tempered with caution.