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Class Legality

IJSBA · sport

Sport GP

IJSBA 2025, SPGP. A closed-list class. The craft must stay stock except where the rules allow otherwise, so anything unlisted is not permitted.

  • 2Not permitted, not listed in the rules
  • 24Legal, with conditions
  • 35Legal

Read out of the published IJSBA rulebook on 2026-09-07, so confirm anything that decides a purchase. The full note is at the foot of the page.

Running the class

Eligible craft
Must begin with a stock OEM watercraft as the base unit. Hull, top deck and engine may originate from other sources but are treated as modifications to that original OEM starter unit.
Displacement limit
1100cc for forced induction. Displacement must not exceed the class designation, and the number in the class name governs. Forced induction: a supercharger or turbocharger may be added only to four-stroke engines of 1100cc or less; four-strokes above 1100cc must remain naturally aspirated (SPGP.9.1). Above 1600cc: PWC homologated above 1600cc must maintain the original stroke (SPGP.4.5).
Licence or tier
Not stated beyond "not intended for entry-level competitors".
Minimum weight
A four-stroke Sport PWC with a supercharger or turbocharger must weigh within 40% of the weight of the original donor PWC (SPGP.2.1). No absolute figure. No requirement for NA or two-stroke craft.

Read from the same class section as the part answers. The rider side of the sport, tiers, ages, licences and what gets inspected, is set out across the bodies at Racing.

Open questions on this class (5)

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.

  • No specific eligible model names or model years are listed.
  • The term Sport hull is never dimensionally defined in this document.
  • No absolute displacement ceiling - the class designation number governs.
  • No rider age, licence, or amateur/pro rules.
  • The 12.00 PSI boost limit was subject to a stated pre-2025-World-Finals revision window. Confirm the current figure.

What the rules say (61 parts)

35 permitted outright, 24 permitted with stated conditions and 2 refused by our reading of the class rather than by a quoted rule. Grouped where the same rule gives the same answer, so two "Not legal" groups can sit side by side under different rules.

What each answer below means

Not permitted, not listed in the rules
Treat it as coming off. The class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list, so this is our reading rather than a rule we can quote at you.
Legal, with conditions
Keep it, but measure it: the rules permit this part only inside stated limits.
Legal
Keep it. The rules permit this part in this class.

Read the refusals as a list of work. Anything below marked Not legal, OEM part required, or Not permitted has to come off the machine, or go back to the standard part, before it races in this class.

Not permitted, not listed in the rules1 part

Sport GP names no eligible craft, so an X2 can race here. SPGP.3.9 opens the handlebar, throttle, cable and grips, the steering shaft, its holder and the handlebar holder, but not the pole, and changes not listed are not permitted. SPGP.1.1, SPGP.3.9

Not permitted, not listed in the rules1 part

Not listed in this class document. Illegal under the closed-list principle.

Legal, with conditions1 part

The exhaust system, which this clause names as the manifold, head pipe, expansion chamber, waterbox and mufflers, may be modified or aftermarket, and an insert in the stinger is part of it. No tuned portion of the exhaust may protrude outside the hull. SPGP.4.8

Legal, with conditions1 part

Original injectors may be modified to increase fuel flow; aftermarket injectors that increase FUEL flow only. Injectors that increase AIRFLOW are prohibited. SPGP.6.1

Legal, with conditions1 part

Four-stroke craft may use aftermarket fuel pumps that stop automatically when the engine stops; two-stroke craft may use modified or aftermarket electric pumps of no more than 4 psi, also with automatic shutoff. SPGP.6.1, SPGP.7.2

Legal, with conditions1 part

Must fit the OEM battery box and be securely fastened. GP/Open/Freestyle/Sport GP additionally allow an additional battery, a new box and relocation.

Legal, with conditions1 part

Cylinders may be interchanged between same-manufacturer homologated craft; ports may be added, deleted or reshaped; BUT two-stroke cylinder or crankcase MODIFICATIONS require written IJSBA approval. SPGP.5.5

Legal, with conditions1 part

Four-stroke 1100cc or less only. Boost relief valve set to release above 12.00 PSI, +/-1 PSI tolerance, never above 13.00 PSI. SPGP.9.1

Legal, with conditions1 part

The impeller housing may be modified or aftermarket, and the wear ring is the liner inside that housing rather than a part the document names on its own. SPGP.10.1

Legal, with conditions1 part

Couplers, bearing housing and driveshaft may be modified or aftermarket provided they keep a 1:1 drive ratio between the engine and the pump. The clause names no material, so a titanium shaft is covered by it. SPGP.11.2

Legal, with conditions1 part

Extension may not be wider than the OEM plate, sides must be connected and radiused, and no fins, rudders or skegs. Max extension beyond the OEM plate: 100.00mm (3.94 in) Ski and Sport, 177.80mm (7.00 in) Runabout.

Legal, with conditions1 part

Full-length type with at least one bar parallel to the drive shaft, all leading edges radiused, extending no more than 12.00mm (0.47 in) below the flat plane of the pump intake area.

Legal, with conditions1 part

Padding and/or mat kits may be added in every class. Where footwells exist they must be BLOCKED OFF during competition with no indentation into the footwell sides.

Legal, with conditions1 part

Permitted only on watercraft homologated in numbers of 500 or higher, and the hulls themselves must be IJSBA-approved and homologated. SPGP.3.2

Legal, with conditions1 part

Replacement bumpers allowed provided no hazard is created. A soft flexible water-spray deflector may attach to the hull sides or bond flange, not extending beyond the perimeter of the OE bumper or side moldings as measured by plumb line. A permanently affixed IJSBA-approved nose bumper is REQUIRED under GEN.8.12.

Legal, with conditions1 part

Allowed in essentially every class. Universal prohibitions: no manually controlled devices that alter cooling water flow during operation, no electronically controlled valves or water injection unless original equipment, and in most stock classes no NEW fittings added to the cylinder head, cylinder or crankcase.

Legal, with conditions1 part

Constant mass only, within the normally exposed areas of the hull, creating no hazard and requiring no modification or relocation of other parts. Water and any other fluid ballast is prohibited in every class.

Legal, with conditions1 part

The class counts any extension mounted on the transom as a trim tab, which may be fixed, automatic or rider controlled but no wider than the planing surface and no more than 100mm (3.94 in.) past its end, as on the trim tab rows. SPGP.3.6

Legal1 part

The exhaust system may be modified or aftermarket on every engine, the two-stroke manifold and head pipe and the four-stroke manifold and connecting pipes included. SPGP.4.8, SPGP.5.9

Legal1 part

Carburetors may be modified or aftermarket if they do not vent or spill fuel, with no more venturis than cylinders and no slide-type carburetors. SPGP.6.4, SPGP.7.1

Legal1 part

The carburetor may be modified or aftermarket provided it cannot vent or spill fuel at any attitude, which covers its jets, needle valves and needle valve springs. SPGP.6.4, SPGP.7.1

Legal1 part

Must meet USCG, SAE J-1928 Marine or UL-1111 Marine backfire flame arrester standards.

Legal1 part

Modified or aftermarket filler cap allowed provided no hazard is created. The FILLER and RELIEF VALVE themselves must stay OEM.

Legal1 part

Engines may be bored and aftermarket piston assemblies are allowed, with displacement kept within the class limit. SPGP.4.4, SPGP.5.1

Legal1 part

Aftermarket camshafts are allowed if the original number of camshafts, the original bearing type and dimensions and the original method of valve activation are kept, and cam timing may be changed. SPGP.4.3

Legal1 part

Aftermarket valvetrain components, valve springs and retainers included, are allowed provided the original method of valve activation is kept. SPGP.4.3

Legal1 part

Forced induction is allowed only on four-stroke engines of 1100cc or less, and there the original turbocharger or supercharger may be modified or an aftermarket unit fitted, so its internals, clutch, belt and pulleys are open. SPGP.9.1, SPGP.9.2

Legal1 part

The original bilge pump may be modified or disconnected and aftermarket bilge draining systems are allowed, provided no hazard is created.

Legal1 part

Replacement engine mounts are allowed in every class that addresses them. Ski GP, Vintage and Freestyle additionally allow a modified or aftermarket ENGINE BED with the engine repositioned in the hull.

IJSBA 2025, SPGP, read from the rulebook on 2026-09-07. Read the rule yourself. Every IJSBA class · where the rulebooks differ · how this site reads a rulebook.

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.

What we corrected here, and when

  • Replacement wear ring. Corrected 2026-10-01: this row read as unanswered until SPGP.10.1 was read against it, and the clause opens the housing the ring sits in.
  • Stinger reducer insert + cooling line. Corrected 2026-10-01: this row read as unanswered until SPGP.4.8 was read against it, and the clause opens the whole exhaust system.
  • Titanium driveshaft, impeller housing or stator vane assembly. Corrected 2026-10-01: this row read as unanswered until SPGP.11.2 was read against it.
Cite this page

“Sport GP, IJSBA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ijsba/sport-gp/

Add the date you read it.

61 parts read · 35 permitted, 24 with conditions · 2025 rulebook

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