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A conversion to water cooling is a large and complex step in engine tuning.

worb5 vespa lambretta water cooling cylinder

Cylinder modification
Some air-cooled cylinders can be equipped with a water jacket. This is actually only possible with aluminum cylinders, e.g. Vespa PX 200 Malossi and Lambretta TS1. These aluminum alloys can be welded very well. More important, however, is the fact that the stud bolt holes lie in a kind of channel from the factory. That they would never come into contact with the cooling water. In the case of cylinders, the open standing pin channels, i. you can see the studs when you look outside through the cooling ribs, it is difficult to get a seal. We can not offer a satisfactory solution for this. If a cylinder is jacketed, the middle cooling ribs are removed 70% and a 1.5 mm aluminum plate is placed around the cylinder. It is necessary to specify where the water connections should be, since a water separation wall must be used. This partition is intended to force the cooling water to circulate once around the cylinder.

worb5 vespa lambretta water cooling cylinder

Accordingly, both water connections should be close to each other - separated by the partition wall. It is also important to ensure that ventilation is provided at the top or the highest points in the circuit to ensure filling of the circuit. Often a small 8 mm aluminum tube is sufficient, e.g. is placed on top of the cylinder and is closed with a blind plug, depending on the type.
It is absolutely necessary to re-coat the welded cylinder after the conversion. The warpage, which occurs during welding, is kept relatively small by "slow" welding. Especially in the case of the cylinder bore, it depends on every hundredth of a circle.

worb5 vespa lambretta water cooling cylinder

Cylinder head
Closed system. Do not touch the studs with the water. NO anger with water loss. We do not offer cylinder heads from the bar. We do not think this is possible at all, since every customer places different requirements on his head. Whether the position of the water inlet and outlet, the combustion chamber shape (crimping edge and geometric compression) or the individual production of threads for thermocouples and thermoswitches. Thus, e.g. a water separation wall can be welded into the head internally when the water connections are close to one another to ensure circulation of the water.

worb5 vespa lambretta water cooling

This is not necessary when the connections are placed in "approximately opposite position". The heads are manufactured according to customer requirements. Enclosed in each case 4 thick stainless steel washers for under the cylinder stud bolt nuts.

worb5 vespa lambretta water cooling cylinder
In principle, it is said that most radiators are chosen to be too small in size. A hidden small cooler under the side hood will certainly fail at 35 degrees outside temperature in the summer at full throttle on the highway. A radiator belongs in the wind.

worb5 vespa lambretta water cooling

The mopped coolers available on the market do not really fit nicely. The water inlet and the water outlet, as well as the filler neck, are often in the wrong place. Mounts for proper attachment are missing. It does not have to be. We change coolers tailor-made so that there is no trouble with the location of the cooling water hoses. Brackets are welded. Important are mainly rubber mountings, so that the cooler does not become tense or vibrates - cracks are thus avoided. All coolers are pressed in a water bath at 2 bar. This guarantees absolute impermeability - even with the most blatant modification. Some used radiators we have stocked there. Just ask.
It is also possible to build complete radiators. To this end, we take qualitatively very high-quality aluminum cooler meshes from the motor racing from a German manufacturer - not to compare with the "Italian" of e.g. Polini. These basic cooler grids can be made in all possible sizes. These nets are then equipped with water boxes, water connections and brackets according to customer requirements.

worb5 vespa lambretta water cooling
Water pump
We only use 12 Volt DC water pumps from Bosch. Likewise, there are beautiful rubber-bearing brackets.

worb5 vespa lambretta water cooling

Temperature and temperature control
Temperature plays a decisive role. The water pump is controlled by an electric thermoswitch.

worb5 vespa lambretta water cooling display

We have these in various temperature ranges. A switch with e.g. 70/75 degree should be attached to the cylinder head. At a water temperature of 75 ° C, the water pump switches on the water pump and exits at 70 degrees. Preferably, we use switches with lower temperatures, e.g. 60/65 degrees. However, a sufficiently large cooler is necessary for this purpose. The pump should operate in the optimum case in a uniform interval: run for about 5 to 10 seconds and NOT run at least the same time. If this is not the case, the cooler is too small or the thermoswitch too cold. But you should not go above 70/75 degrees. In order to perform a water filling, the pump should be able to run continuously to get the air out of the system (at 20 ° C water temperature). Therefore, it is useful to install a change-over switch with which you can choose: pump off, pump via thermoswitch or pump. In order to keep the temperature constantly in view, a temperature display with a thermocouple makes sense.
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