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Ski Division GP2

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Ski Division GP2

UIM2026, 501.03. A closed-list class. The craft must stay stock except where the rules allow otherwise, so anything unlisted is not permitted.

Open questions on this class (4)

Places where the rulebook contradicts itself, or where a figure could not be settled. Nothing in this list is decided, and it sits here rather than in a footnote because it is what you would want before spending money.

  • The 750 cc turbo limit is not cross-confirmed against the 302.01 table.
  • The HSR-Benelli "limited to 10-14 psi" phrasing is odd for a limit - permitted band or maximum is unresolved.
  • No ballast article, so whether ballast may be used to reach the 135/165 kg minima is not stated.
  • No separate four-stroke exhaust rule was found (501.03.03.07 sits under the two-stroke engine article).

What the rules say (66 parts)

50 permitted outright, 4 answered by our reading of the class rather than by a quoted rule, 2 the rules do not settle. Grouped by the answer, because an open class gives one answer to most questions and printing it once per part would say the same sentence forty times.

Not permitted, not listed in the rulesOur reading, not a rule we can quote at you. This class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list.

Not legal1 part

Sensors and actuators must remain original; no aftermarket ECU allowance. 501.03.08

OEM part required1 part

THE OEM WATERBOX MUST BE USED AND MAY NOT BE MODIFIED, even though the chamber may be aftermarket. 501.03.03.07

OEM part required1 part

Camshaft and crankshaft must remain stock. 501.03.04

OEM part required1 part

The valves themselves must remain original. 501.03.04

The rules do not say1 part

Not restated for GP2. GP2 inherits GP3 permissions, so it probably carries over, but the rulebook does not say so.

Legal, within limits1 part

Manifold, head pipe, expansion chamber, gaskets and the chamber-to-waterbox hose may be modified or aftermarket. The OEM WATERBOX must be used unmodified, the exit opening size and position must be maintained, and no tuned portion may protrude outside the hull. 501.03.03.07

Legal, within limits1 part

Permitted subject to SAE J30R9 high-pressure hose, A.N. threaded fittings or equivalent with non-removable crimped clamps, metal-type filters only on the high-pressure side, and a fuel pump that stops automatically when the engine shuts off. 501.03.05.03

Legal, within limits1 part

Aftermarket or modified electric fuel pumps not exceeding 4 psi, stopping automatically when the engine shuts off. Manually operated on/off pumps prohibited. 501.03.05

Legal, within limits1 part

Modified or aftermarket, not exceeding 5 cm x 15 cm, with a return line to the tank open at all times. 501.03.05

Legal, within limits1 part

Must fit the OEM battery box and be securely fastened. GP2 additionally allows relocation of the battery, box or housing limited to the strict minimum needed to fit an aftermarket exhaust.

Legal, within limits1 part

Cylinders may be machined to accept girdle-system cylinder heads. If OEM cylinders do not give displacement within 10% of the maximum allowable, an aftermarket cylinder SLEEVE may be used, keeping the same port sizes and specifications as the original OEM sleeve. 501.03.03.14

Legal, within limits1 part

Turbocharged permitted, capped at 750 cc. The only named boost figure in the whole rulebook is 10-14 psi for the HSR-Benelli S4 (501.03.04-09), and that phrasing is ambiguous.

Legal, within limits1 part

Permitted for the HSR-Benelli S4 specifically - intercooler and lines may be replaced or aftermarket. 501.03.04-09

Legal, within limits1 part

Permitted subject to the universal limits in uim-globals.yaml constants.

Legal, within limits1 part

Modified or aftermarket. The complete pump and nozzle assembly may be no more than 50.00 mm longer than OEM, and a 1:1 drive ratio must be maintained. 501.03.09/.10

Legal, within limits1 part

Modified or aftermarket provided a 1:1 drive ratio is maintained. TITANIUM driveshafts, impeller housings and stator vane assemblies are PROHIBITED. 501.03.09

Legal, within limits1 part

Full-length type with at least one bar parallel to the drive shaft, all leading edges radiused, extending no more than 12.00 mm below the flat plane of the pump intake area. GP1 adds that the projecting member must be filed so as not to create a hazard.

Legal, within limits1 part

Max 153 cm each, 210 cm total, via the Kawasaki SXR1500 derogation. 501.03.02

Legal, within limits1 part

Replacement bumpers allowed. A soft flexible water-spray deflector may attach to the hull sides or bond flange, not exceeding the perimeter of the original bumpers or the external hull edge measured with a plumb line. SAFETY BUMPERS ARE COMPULSORY in both GP1 classes.

Legal, within limits1 part

All cooling system valves must be of FIXED OR AUTOMATIC type - thermostats, pressure regulators, solenoids. Manually controlled devices that alter cooling water flow while under way are prohibited in every class, as are electronic water injection systems unless of origin.

Legal1 part

Two-stroke cylinder head AND GASKET may be modified or aftermarket. 501.03.03

Legal1 part

Diameter constraint lifted for two-stroke; impeller, housing, stator, plate and shoe all modifiable. 501.03.09

Legal1 part

Aftermarket hoods may be used and OEM hoods may be modified. 501.03.02

Legal1 part

Padding and mat kits may be added and custom painting is allowed. Metal components above the bond flange may be polished, shot peened or painted.

UIM 2026, 501.03, read from the rulebook on 2026-09-08, not verified by a racer. Read the rule yourself. Every UIM class · where the rulebooks differ.

This is one class. Every part below also has a page of its own showing where it stands across every class this body runs, and legality by part is the index of them.

66 parts read · 50 permitted outright · 2026 rulebook

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