Not legal1 part
SKSS.1.1
- Aftermarket hull or top deck · Hull and handling
IJSBA · ski
Ski Superstock
IJSBA2025, SKSS. A closed-list class. The craft must stay stock except where the rules allow otherwise, so anything unlisted is not permitted.
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. Do not encode either "ECU unrestricted" or "ECU prohibited".
- Crankshaft weight tolerance returned as "+/5.00%" - read as +/-5.00% but verify.
- No reed, forced induction, ride plate, seat/tray, weight or racing number rules located.
What the rules say (50 parts)
40 permitted outright, 5 answered by our reading of the class rather than by a quoted rule, 4 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 permitted, not listed in the rules5 parts
Not listed in this class document. Illegal under the closed-list principle.
- Carb jet kit, needle valve, needle valve spring · Fuel
- Supercharger rebuild internals, clutch, belt, pulleys · Forced induction
- Aftermarket intercooler · Forced induction
- Titanium driveshaft, impeller housing or stator vane assembly · Driveline
- Rider-controlled or automatic trim tab system · Hull and handling
The rules do not say1 part
No ignition/ECU section was found in SKSS. Do not assert either way.
- ECU reflash / reprogramming of the OEM unit · Ignition
The rules do not say1 part
No ECU section found.
- Aftermarket standalone ECU · Ignition
The rules do not say1 part
Not addressed in this class document.
- Aftermarket or lightened flywheel · Ignition
The rules do not say1 part
No forced-induction section located in SKSS.
- Aftermarket turbocharger or supercharger · Forced induction
Legal, within limits1 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
- Aftermarket fuel injectors · Fuel
Legal, within limits1 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, within limits1 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.
- Replacement battery · Electrical
Legal, within limits1 part
Ferrous materials only; rod length modification allowed. SKSS.3.7
- Aftermarket connecting rods · Engine
Legal, within limits1 part
Max 50.00mm over OEM overall. SKSS.6.1
Legal, within limits1 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.
- Aftermarket pump cover plate / extension · Driveline
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 12.00mm (0.47 in) below the flat plane of the pump intake area.
- Aftermarket intake grate · Driveline
Legal, within limits1 part
Max TWO. Max 38.00mm drop.
- Aftermarket sponsons · Hull and handling
Legal, within limits1 part
Replica trim plates only.
- Aftermarket FIXED-position trim tab / ride plate extension · Hull and handling
Legal, within limits1 part
The handlebar must be padded at the mounting bracket, or the crossbar padded if fitted. This is a tech-inspection item.
- Aftermarket handlebars, throttle, throttle cable, grips, switches · Hull and handling
Legal, within limits1 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.
- Footholds, tray mats, padding kits · Hull and handling
Legal, within limits1 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.
- Replacement bumpers and water-spray deflectors · Hull and handling
Legal, within limits1 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, within limits1 part
Fixed-type or automatic valves only. Thermostats, pressure regulators and solenoids qualify. Manual actuation of any kind during operation is prohibited everywhere.
Legal, within limits1 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.
- Ballast weight kits · Hull and handling
Legal3 parts
Explicitly permitted by this class document.
- Aftermarket valve springs and retainers · Engine
- Replacement wear ring · Driveline
- Aftermarket handlepole / pole bracket · Hull and handling
Legal2 parts
SKSS.3.8
- Aftermarket exhaust manifold / head pipe · Exhaust
- Aftermarket waterbox · Exhaust
Legal2 parts
SKSS.6.1
Legal1 part
Through-hull exhaust modified or aftermarket; exit may be relocated to the transom below the bond flange. SKSS.3.8
Legal1 part
SKSS.5.3
- Aftermarket intake manifold · Fuel
Legal1 part
Must meet USCG, SAE J-1928 Marine or UL-1111 Marine backfire flame arrester standards.
- Aftermarket flame arrester · Fuel
Legal1 part
Aftermarket fuel pumps allowed; must auto-stop when the engine shuts down. SKSS.5.1
Legal1 part
Modified or aftermarket filler cap allowed provided no hazard is created. The FILLER and RELIEF VALVE themselves must stay OEM.
- Aftermarket fuel filler cap · Fuel
Legal1 part
Modified or aftermarket, butterfly count up to the number of cylinders. SKSS.5.3
Legal1 part
Aftermarket spark plugs of a different heat range are allowed in every class that addresses them.
- Aftermarket spark plugs of a different heat range · Electrical
Legal1 part
Aftermarket piston assemblies. SKSS.3.2
- Aftermarket piston assemblies · Engine
Legal1 part
Entire crankshaft assembly including connecting rods may be modified or aftermarket, total weight within +/-5.00% of OEM. SKSS.3.6
Legal1 part
SKSS.3
- Aftermarket camshafts · Engine
Legal1 part
Intake and exhaust ports may be modified in diameter and shape, runners modified or built up, combustion chambers modified. SKSS.3.2
Legal1 part
Superseded by the full porting allowance.
Legal1 part
Diameter constraint lifted. SKSS.6.1
- Aftermarket impeller at OEM diameter · Driveline
Legal1 part
Aftermarket steering shaft, steering shaft holder, handlebar holder and steering cables are allowed. Quick-turn modifications that alter the steering ratio are allowed in most stock classes.
- Aftermarket steering shaft, shaft holder, handlebar holder, steering cables · Hull and handling
Legal1 part
Hood modified or aftermarket. SKSS.2.9
- Aftermarket hood / engine cover · Hull and handling
Legal1 part
The original bilge pump may be modified or disconnected and aftermarket bilge draining systems are allowed, provided no hazard is created.
- Aftermarket bilge draining system · Hull and handling
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.
Legal1 part
Replacement starter motor and bendix are allowed in every class that addresses them.
- Replacement starter motor and bendix · Electrical
IJSBA 2025, SKSS, read from the rulebook on 2026-09-07, not verified by a racer. Read the rule yourself, Ski Superstock. Every IJSBA 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.
50 parts read · 40 permitted outright · 2025 rulebook