Building on it's reputation for building world beating two-stroke minicross machines, Polini have developed the all-new XP 4 Stroke. We highlight all the new Resources here.

MADE TO BE NUMBER ONE

In 1998 Polini Motori tested itself with a hard project for the young minicross riders, signing its own minicross bikes with XP mark. In 7 years it has produced 15 different models of XP minicross bikes, divided into 5 evolutions, all with two stroke engines, air or liquid cooled, from 50cc to 65cc. Forgot the history, now Polini Motori, after the production of minicross bikes equipped with two stroke engines, looks at the future with the new XP 4 STROKE minicross bikes. Yes, here it is: a new minicross with a four stroke engine. Charming in its aesthetic, and very INNOVATIVE. The technical solutions are very refined. The frame is perfectly balanced thanks to the lower barycentre. The liquid cooled 4 stroke engine, 107cc, has 4 speed. The new XP 4 STROKE is a modern minicross bike, with a very good price/quality ratio. It has been designed with a great care in all the details, such as all the Polini products. From the frame to the shock absorbers, from the design to the finishing touches. Every single detail has been studied to satisfied the needs of all the riders. The new open single beam frame with lateral steel box-type stays and the trapezoidal swing arm, let you exploit to the utmost all the ?horse power?. The main structure optimises the weight distribution, assuring great improvements, such as better handling and stability on uneven ground. The rear suspension with one shock-absorber is innovative, using a new fixing system in the lower side. It improves traction when laying the trajectory and gives more agility to the bike after the curve. It avoids tail jumping and loss of adhesion to the ground. The line is modern and elegant. It shows finishing touches of high level; shock-resistant and non-scratch light plastics of blue colour, metal paint grey frame with non-scratch adhesives. As always the most important Resources are of very high quality. The exhaust system is hand made with final silencer made of light alloy with oval section; it optimises the gas scavenging. The mechanical disc brakes measure 150mm (both front and back). The hydraulic fork, with legs of d. 33 has been calibrated to work at the best on every ground, also for riders and adults who weight more than children. Legs and sleeves have been reinforced and the rear wheel excursion is of 175 mm. The steering tube is placed on cylindrical rollers bearings, and this is the best solution to grant stability on uneven ground. The handlebar is in light alloy with reinforced axle and buffers so that taller riders can drive it easier, and they have the possibility to maintain a natural position even in the narrower curves. The steel rims are assembled on light alloy hubs with straight spokes. The seat is covered by antiskid material.

POLINI 4 STROKE ENGINE
The mono-cylindrical engine is air cooled with crankcase in light alloy, die-cast. The cylinder is in lamellar cast-iron. The head is a single-shaft model with two valves battery. The barrel is made of lamellar cast-iron too; it has a bore and stroke of 52,4 and 49,5. The displacement is 107 cc. It is air cooled. The multi-disc clutch has spring drives assembled on the primary speed shaft. The lubrication is in the wet crankcase. The 4 speed gear has straight teeth. The gear ratio is specific for the off road tracks and drive. The 22mm carburettor is by Mikuni. The air box is made of shockproof material. The sponge filter with open micro-cells can keep and filter every kind of matter.

POLINI TUNING CYLINDER KIT FOR HONDA XR5 AND MINICROSS XP 4: FOR RACE PERFORMING KIT.
Polini Motori has designed a new cylinder kit with bore 52,4 that can be fitted both on the XP 4 minicross bike and on the same 4 stroke engine assembled by different manufactures on their scooters and motorcycles. This kit has really performing Resources. It includes cylinder, piston and head. Every single part has been studied by Polini's engineers to assure the best yield and optimises the power output at every rpm. The cylinder is in light alloy with nichel-silicium coating. It assures high resistance to heat and abrasion. If you assemble this cylinder kit on a minicross Honda XR 50, it increases the displacement to 90cc, while on a Polini minicross XP 4 it reaches 107cc. The piston is in aluminium die-cast at high silicon content. The head is made of aluminium alloy and gravity chilled. It has been designed just for the PRO/ENGINEERING three-dimensional system. The new head Resources a single-shaft distribution devise with 4 valves. It distinguishes itself for the smaller angle between the valves and for the burning chamber which is extremely small with the spark plugs placed in the centre and adequate to the squish, assuring great performance. It optimises the power output and reliability. The distribution diagram is the result of hard tests made in the Polini's workshop on state-of-the art electronic testing desks. The specific tests have let the engineers reach the best torque value without reducing the power output at the runway speed rate. All the working processes have been done using the most advanced production technologies. They assures a high quality level, maximum reliability and safety. The kit will be sold on the market in two versions: cylinder and piston or head kit only.