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ProX Piston 4T


Over 35 years experience in piston manufacturing! Pistons from ProX is a perfect choice when it's time for piston replacement.

ProXimity is one of the world's largest manufacturer of racing pistons. They have provided the market with good and affordable pistons since 1975. ProX pistons match the original piston but at a much lower price.

All ProX 4-stroke pistons are forged!

Made of aerospace aluminum and CNC machined from one piece for optimal shape and long life. ProX 4-stroke pistons are CNC machined in Japan.

All pistons come with piston rings, piston pin and clips of the best quality

B-piston we recommend for everyone to use cylinders.

A piston is for new cylinders.

A flask B is one hundredth of a millimeter greater than the A-piston, in order to compensate for wear. C piston is larger than the B flask and so on.

Considerations for piston replacement:
If the old piston is defective, investigate the cause and correct the error. Error fuel mixture, may cause värmenypning. Too low a heat range of spark plugs, ignition misconfigured or air leakage are leading causes of burned pistons.

If the old piston has been shattered or completely burned through, remove the crank case and carefully clean the metal debris.

Check the cylinder for wear, taper and ovality. A cylinder wear unevenly and therefore it is important to check the dimensions of the cylinder carefully.

During assembly of the piston:
Always replace gaskets with new ones!

The flask was fitted with the arrow pointing towards the exhaust side. Plunger bolt locking rings are placed carefully with locking opening downward.

Install the piston rings on the piston. Be aware that some pistons are equipped with keystone piston rings. These are conical and can easily be positioned incorrectly. Check that the piston rings go completely into the ring groove and the ring gap closes completely over the piston ring plug.
Lubricate all parts with engine oil 10W30 or 10W40.

Place a new cylinder foot gasket on the crankcase, compress the piston rings and allow the cylinder to slide gently down into position. Before installing the cylinder head to the crankshaft. Check that the piston with rings moves freely in the cylinder.

Remanufactured engines require some break-in. Adjust the gasifier to a slightly richer fuel mixture. Avoid riding at extremely high or low speeds, varying the riding speed and not accelerate at full throttle. After an engine overhaul, additional oil added to fuel.

Pistons are manufactured in very large series, and the material is just a very, very small part of production costs. This means that no manufacturers skimp on materials. If a new piston goes down, it depends not on the piston itself. Common errors are to be mounted piston in an unevenly worn cylinder, mounted piston rings wrong, wrong carburetor, incorrect fuel mixture or that it has other damage to the connecting rod / crankshaft.