Over 35 years experience in piston production! ProX pistons are the perfect choice when it's time fora piston change.
ProX is one of the world's largest manufacturers of racing pistons. Since 1975, they have provided the market with good and affordable ones. ProX pistons correspond to the original pistons, but at a significantly lower price.
Made of Aerospace aluminum and CNC cut-out for optimal shape and long life. ProX 4-stroke pistons are forged in Japan.
All pistons are supplied with piston rings, piston bolt and the best quality clips.
We recommend B-piston for all used cylinders.
A-pistons are for new cylinders.
A B-piston is 1/100 of a millimeter larger than an A-piston, this to compensate for wear. C-piston is larger than B-piston etc.
To think about when changing piston:
If the old piston is defective, investigate the reason and correct whatever is wrong. An incorrect mix of fuel may cause a piston seizure. Too low heat on spark plugs, improper ignition or air leakage are common causes of burnt pistons.
If the old flask has been shattered or completely burnt, remove the crankcase and clean thoroughly from metal residues.
Check the cylinder for wear, conicity and ovality. A cylinder is unevenly worn and it is therefore important to carefully check the dimensions of the cylinder.
When installing a piston:
Always replace old gaskets with new ones!
Mount the flask with the arrow pointing towards the exhaust side. The piston bolt locks are carefully positioned with the lock opening downwards.
Fit the piston rings on the piston. Keep in mind that some pistons are equipped with keystone piston rings. These are conical and can easily be placed incorrectly. Check that the piston ring is fully inserted into the ring groove and that the ring gap is completely closed over the piston ring.
Lubricate all parts with engine oil 10W30 or 10W40.
Mount the piston with the arrow pointing towards the exhaust side. The lock rings of the piston pin are carefully positioned with the lock opening facing down.
Fit the piston rings on the piston. Keep in mind that some pistons are equipped with keystone piston rings. These are conical and can easily be placed incorrectly. Check that the piston ring is fully inserted into the ring groove and that the ring gap is completely closed over the piston ring circlip.
Lubricate all parts with engine oil 10W30 or 10W40.
Place a new cylinder foot seal on the crankcase, compress the piston rings and gently slide the cylinder down into position. Before installing the top cover, turn crankshaft by hand. Check that the piston with rings is moving freely in the cylinder.
Refurbished engines require some running. Adjust the carburettor to a slightly more fat fuel mixture. Avoid riding at extremely high or low speeds, vary riding speed and do not accelerate with full throttle. After a motor refurbishing, additional oil must be added to the fuel.
Pistons are manufactured in very large series and the material is only a very, very small part of the manufacturing costs. This means that no manufacturers are holding back when it comes to selecting materials. If a new piston breaks, it never depends on the piston itself. Common mistakes are that you install the piston in an unevenly worn cylinder, mounted the piston rings wrong, have incorrect carburettor settings, incorrect gasoline blend or possibly a crankshaft damage.
ProX is one of the world's largest manufacturers of racing pistons. Since 1975, they have provided the market with good and affordable ones. ProX pistons correspond to the original pistons, but at a significantly lower price.
Made of Aerospace aluminum and CNC cut-out for optimal shape and long life. ProX 4-stroke pistons are forged in Japan.
All pistons are supplied with piston rings, piston bolt and the best quality clips.
We recommend B-piston for all used cylinders.
A-pistons are for new cylinders.
A B-piston is 1/100 of a millimeter larger than an A-piston, this to compensate for wear. C-piston is larger than B-piston etc.
To think about when changing piston:
If the old piston is defective, investigate the reason and correct whatever is wrong. An incorrect mix of fuel may cause a piston seizure. Too low heat on spark plugs, improper ignition or air leakage are common causes of burnt pistons.
If the old flask has been shattered or completely burnt, remove the crankcase and clean thoroughly from metal residues.
Check the cylinder for wear, conicity and ovality. A cylinder is unevenly worn and it is therefore important to carefully check the dimensions of the cylinder.
When installing a piston:
Always replace old gaskets with new ones!
Mount the flask with the arrow pointing towards the exhaust side. The piston bolt locks are carefully positioned with the lock opening downwards.
Fit the piston rings on the piston. Keep in mind that some pistons are equipped with keystone piston rings. These are conical and can easily be placed incorrectly. Check that the piston ring is fully inserted into the ring groove and that the ring gap is completely closed over the piston ring.
Lubricate all parts with engine oil 10W30 or 10W40.
Mount the piston with the arrow pointing towards the exhaust side. The lock rings of the piston pin are carefully positioned with the lock opening facing down.
Fit the piston rings on the piston. Keep in mind that some pistons are equipped with keystone piston rings. These are conical and can easily be placed incorrectly. Check that the piston ring is fully inserted into the ring groove and that the ring gap is completely closed over the piston ring circlip.
Lubricate all parts with engine oil 10W30 or 10W40.
Place a new cylinder foot seal on the crankcase, compress the piston rings and gently slide the cylinder down into position. Before installing the top cover, turn crankshaft by hand. Check that the piston with rings is moving freely in the cylinder.
Refurbished engines require some running. Adjust the carburettor to a slightly more fat fuel mixture. Avoid riding at extremely high or low speeds, vary riding speed and do not accelerate with full throttle. After a motor refurbishing, additional oil must be added to the fuel.
Pistons are manufactured in very large series and the material is only a very, very small part of the manufacturing costs. This means that no manufacturers are holding back when it comes to selecting materials. If a new piston breaks, it never depends on the piston itself. Common mistakes are that you install the piston in an unevenly worn cylinder, mounted the piston rings wrong, have incorrect carburettor settings, incorrect gasoline blend or possibly a crankshaft damage.