·    30 mm main rails

:

Bore

Stroke

Displacement

Clutch

Dry centrifugal clutch

:

Engine Type

:

Air cooled 4 stroke OHV petrol engine, 25° inclined cylinder, horizontal shaft. Top tank (pictured) removed and pulse pump and central remote fuel tank fitted.

Bore & Stroke

:

68 mm

Stroke

:

45mm

Displacement

:

163cc

Compression Ratio

:

8.5 : 1

Optimum Power Output

:

5.5hp at 4000rpm

Maximum Torque

:

10.8 Nm at 2500rpm

Ignition System

:

Transistorised magneto

Starting System

:

Recoiling Pullcord

Spark Plug

NGK BP6 ES

Carburetor

Horizontal, butterfly valve

Oil Capacity

:

0.6 litres

Dimensions (L x W x H)

:

312mm x 362mm x 335mm

Fuel Used

:

Unleaded

Dry Weight

:

15kg

The Prokart is very simple - there is no gearbox , no suspension - just a frame , wheels and engines , indeed at 15kg each , the engines compose most of the weight of the kart. The benefit of the design is that there is very little to go wrong, and it is generally hard wearing, with the exception of tyres. Tyre choice is very important, the main option is between slick tyres or wets which have a tread pattern to allow water to escape. The slicks fitted are very soft and as such are very grippy however the downside is that they wear very quickly. As the tyres are slick there is no way of telling how much wear is left so the manufacturers drill small 'dimples' in the carcass , the depth of which is the amount of tread left.

Whilst there is no gearbox it is possible to alter the gear ratio by changing the sprockets used for the chain to increase top speed or acceleration depending upon the track.

There is not a lot of space and a knees bent driving position is required. The right pedal is the accelerator, the left pedal the brake. There is no clutch pedal as the clutches are centrifugal and engage drive when the engines are revved. Upon setting off, the engines are very audible just behind your elbows and the kart moves off the line quickly with the centrifugal clutches slipping until drive is totally engaged at around ten mph. The kart is only 5 cms off the ground and with no bodywork there is a massive sensation of speed, much more than ever experienced in a car no matter how fast. The engines are very torquey and pull quickly from very low revs right up to the maximum speed. The ground moving past the wheels turns into a blur and you have to close the visor on the helmet quickly as the wind rushes past.

The steering is very direct, every tiny movement of the wheel translates to a change of direction. In the dry the grip available with sticky tyres is massive. The seat is bucketed but as your confidence grows it is harder and harder to stay in the seat during long corners such is the cornering force that can be generated. Karting in the dry is hard physical work and will leave aches and pains the next day! Unlike a car, the limit is abrupt and if exceeded, the back end usually breaks away first and because the kart is relatively short quick steering correction is needed to avoid going onto the grass backwards. The handling in the wet is different - if you are unlucky enough to get caught in the wet on slicks the situation changes a lot. Initially the kart may not turn in properly - understeer , which can flick into oversteer quickly. The situation mid bend is adjustable on the throttle also which is good fun but makes it a bit of a handful.

The brake is a single disk on the back axle which is powerful enough in itself but its' effect in a straight line is limited by the way the weight of a vehicle goes to the front wheels under braking - brake too hard and the axle locks up. If this happens while cornering (especially a problem in the wet) then the back of the kart looses grip and will quickly result in a spin.

This is a very cheap way into motorsport. Racing costs include new wheels and tyres, new chains, and petrol cost as well as track time.

My first kart, Wright chassis with standard Honda GX160 engines