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Class Legality

IJSBA · ski

Ski Superstock

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

  • 1Not legal
  • 1OEM part required
  • 5Not permitted, not listed in the rules
  • 4The rules do not say
  • 15Legal, with conditions
  • 27Legal

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
Exclusively the 1500cc-based Kawasaki SX-R. SKSS.1 prints "The Ski Modified Class is exclusively for the 1500cc based Kawasaki SX-R", a sentence that names the Ski Modified Class although it sits in the Superstock section.
Displacement limit
1500cc (SKSS.3.4). The class document states 1500cc as the maximum displacement that may be achieved in the class, and SKSS.4.4 permits the engine to be bored with the displacement not to exceed the class designation.
Licence or tier
Expert or Pro. See uncertainties - passes disagreed on mandatory vs recommended.
Minimum weight
Not stated in this document.

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 (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.

  • Licence requirement conflicted between passes - "highly recommended" vs "must possess".
  • NO ignition/ECU/CDI/flywheel section was found, so this class document neither allows nor forbids an ECU change and the answer is not in it.
  • Crankshaft weight tolerance printed as "+/5.00%", read here as +/-5.00%.
  • No reed, forced induction, ride plate, seat/tray, weight or racing number rules located.

What the rules say (53 parts)

27 permitted outright, 15 permitted with stated conditions, 1 refused by a rule we can quote, 1 held to the original part by a rule we can quote, 5 refused by our reading of the class rather than by a quoted rule and 4 the rules do not settle. 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 legal
This comes off. The rules refuse it in this class.
OEM part required
This comes off. Only the part the manufacturer fitted is allowed here.
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.
The rules do not say
Unanswered. The rules do not settle this, so ask the club before you rely on it.
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 legal1 part

The class description controls build costs by prohibiting aftermarket hulls, and deck repairs may change the original shape by no more than 2.00mm (0.08 in.). SKSS.1, SKSS.2.2

OEM part required1 part

The hull may be repaired but not otherwise modified, and a repair may not alter the original configuration by more than 2.00mm (0.08 in.). SKSS.2.2

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. SKSS.5.1

Legal, with conditions1 part

An unmodified tank from another homologated PWC; a non-homologated aftermarket tank only by race director approval meeting or exceeding OEM strength and safety. SKSS.5.5

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

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

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.

Legal1 part

Carburetors may be used in addition to or instead of fuel injection, venturi count not exceeding cylinder count. SKSS.5.4

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. SKSS.5.4

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

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. SKSS.3.3

Legal1 part

Aftermarket valvetrain components, valve springs and retainers included, are allowed provided the original method of valve activation is kept. SKSS.3.3

Legal1 part

The document names no wear ring, but the impeller housing it lines may be modified or aftermarket within the 50.00mm (1.97 in.) overall pump and nozzle length limit. SKSS.6.1

Legal1 part

Modified or aftermarket handlepole and mounting bracket, provided it functions as originally designed. Attaching point may be reinforced. SKSS.2.9

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, SKSS, 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.

Cite this page

“Ski Superstock, IJSBA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ijsba/ski-superstock/

Add the date you read it.

53 parts read · 27 permitted, 15 with conditions · 2025 rulebook

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