Not all type 1 engines are equipped with a bearing on the crankshaft pulley side, but the pulley has grooves that rotate in opposite directions so that the engine oil is stopped or pushed, so to speak. In the event of an oil leak, the grooves in the pulley may be worn or, in the worst case, the crankcase may be worn and the oil will no longer be stopped. In the latter case, a Sand Seal type pulley offers a solution. This involves placing an aluminum ring with a replaceable seal in the crankshaft housing (without disassembling the engine) that will ensure the oil seal. After the assembly of the Sand Seal pulley, which no longer has any grooves but closes on the seal, the leak is solved for good. If the seal leaks, you can easily replace it with a new one (see the Spare Parts tab). Mounting a Sand Seal pulley provides a much better seal than a standard pulley, which is why Sand Seal pulleys are often used as standard in the cross and racing world. The Power Sand Seal pulley mentioned here has a smaller diameter than the standard pulley, which ensures greater engine power and higher engine speeds. It is made of polished aluminum and has a black engraved scale. The original steel pulley has a diameter of 170 or 177 mm, depending on the engine power. By keeping the weight lower and reducing the diameter, the performance pulley was created. There are few performance engines that use an original pulley, a performance pulley is part of the standard equipment of this group of motors. When asked how much power this will bring you is difficult to answer, it depends on how your engine is built. But anyway, the power will increase with a performance pulley, although you shouldn't expect miracles from it, it is part of the changes you will make to add power to your engine. When mounting this bolted Sand Seal pulley, there is something to take into serious consideration; the smaller diameter negatively affects the cooling capacity of the air, it is recommended to mount an oil dipstick and possibly adjust your cooling if necessary.
Attention! With bolted pulleys, it is necessary to mount a longer pulley bolt, this type of pulley comes a little further forward and the length of the standard bolt has become too short. Order it separately, the bolt is listed under the options tab. In addition, the ring must be equipped with a liquid seal during installation, which must also be ordered in addition (see the options tab).
Note: Under the Alternatives tab, other Sand Seal pulleys with a standard diameter of 170 mm are listed, as well as the various other performance pulleys that can be mounted directly, they are intended for crankcases that have a good seal.
Instructions
Useful information from Paruzzi magazine and from our YouTube channel :
Look for more technical articles on the page Paruzzi Magazine