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TKART magazine Must Have | 5 axle pulleys for kart water pump transmission
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Gianluca Covini
08 October 2023 • 4 min. read
The kart water pump transmission system is the kinematics at the base of the water circulation inside the cooling circuit of the 2-stroke engine of the kart (to learn more, read "Technique | Cylinder cooling"  and "Technique | The radiator") and consists of three main elements: the pulley on the axle, the drive belt and the axial pulley of the water pump. The pulley placed on the axle, exploiting the rotation of the wheels, has the task of giving motion to the transmission belt, activating the impeller inside the water pump. Replacing the pulley on the axle compared to the original model may be necessary to change the speed of circulation of the liquid inside the cooling circuit, to decrease the rotating masses or simply because the old one has worn out. What are the elements to consider before making a choice? Firstly, attention must be paid to the diameter of the axle, for example, 30, 40 or 50 mm and the type of belt, smooth or toothed. Furthermore, you can choose a lighter material to reduce rotating masses and therefore have a small dynamic benefit in acceleration and braking, or choose a pulley with a primitive diameter, that is, the one measured taking as a reference the inside of the pulley grooves, larger, to make the engine cooling water turn faster.

N.B. Do you think there are other products that can be added to this selection? Don't hesitate to share them with other TKART users in the "Contributions" section at the end of the article. The community will be grateful to you!


The resin pulley (a very hard and abrasion-resistant polymer) is the cheapest version that can be found on the market, it costs about half as much as an aluminium pulley. It is the ideal model for amateur kart drivers, who have no particular pretensions in relation to performance and durability. Being made in two parts, fastened using two screws, it is not necessary to dismantle the axle for its installation. It has two smooth grooves for two straps, the small tubular belts commonly called "O-Ring" or "OR" - which transmit motion through friction. The version that we indicate is suitable for axles from 50 mm in diameter.

Indicative price

About 8,90 euro

To buy:
Photo credit Blukart
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