Not legal1 part
VSK.2.7
- Rider-controlled or automatic trim tab system · Hull and handling
IJSBA · vintage
Vintage Ski
IJSBA2025, VSK. An open class. It carries no clause requiring the craft to stay stock, so anything the rules do not restrict appears to be permitted. That reading is ours rather than the rulebook’s.
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.
- Titanium pump parts ALLOWED here but explicitly PROHIBITED in Vintage X2 and Vintage SC. Confirmed on re-fetch but worth verifying.
- Pump/nozzle limit expressed as 139.7mm (5.5 in) from the transom, an absolute distance, where every other class uses 50.00mm over OEM.
- No model-year cutoff exists anywhere in the document.
- No seat-height limit surfaced, unlike X2 and SC.
- Whether non-Kawasaki craft may enter at all is not addressed.
What the rules say (50 parts)
45 permitted outright, 0 answered by our reading of the class rather than by a quoted rule, 3 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 legal1 part
Upper deck substitution only by IJSBA WRITTEN approval, and the replacement deck must have historical approval in 550 competition.
- Aftermarket hull or top deck · Hull and handling
The rules do not say1 part
Not addressed in this class document.
- Stinger reducer insert + cooling line · Exhaust
The rules do not say1 part
No separate wear-ring rule; treated within the impeller housing.
- Replacement wear ring · Driveline
The rules do not say1 part
No seat-height limit surfaced.
- Aftermarket seat assembly / seat base · Hull and handling
Legal, within limits1 part
Max 4 psi, automatic shutoff. VSK.4.3
Legal, within limits1 part
VSK.4.2
Legal, within limits1 part
Flywheel COVER modified or aftermarket. VSK.5
- Aftermarket or lightened flywheel · Ignition
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
VSK caps the assembly at 139.7mm (5.5 in) FROM THE TRANSOM rather than as a delta from OEM. Verify.
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
Up to FOUR: two traditional bladed plus two Tubbie-type convex appendages. Max 63.5mm drop.
- Aftermarket sponsons · 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
Legal13 parts
Explicitly permitted by this class document.
- Aftermarket exhaust manifold / head pipe · Exhaust
- Aftermarket waterbox · Exhaust
- Through-hull exhaust outlet / relocation kit · Exhaust
- Carb jet kit, needle valve, needle valve spring · Fuel
- Aftermarket reed petals · Fuel
- Aftermarket intake manifold · Fuel
- Aftermarket cylinder head (2-stroke) · Engine
- Aftermarket piston assemblies · Engine
- Aftermarket connecting rods · Engine
- Port chamfering service (within the appendix limit) · Engine
- Aftermarket impeller at OEM diameter · Driveline
- Aftermarket pump/impeller housing, stator vane assembly, pump shoe · Driveline
- Aftermarket nozzle trim system (pump-mounted) · Driveline
Legal1 part
VSK.3.7
Legal1 part
VSK.4.1
Legal1 part
Reed valve assemblies modified or aftermarket. VSK.4.6
Legal1 part
Must meet USCG, SAE J-1928 Marine or UL-1111 Marine backfire flame arrester standards.
- Aftermarket flame arrester · Fuel
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
CDI may be modified or aftermarket; timing may be changed; TOTAL LOSS IGNITION SYSTEMS MAY BE USED. VSK.5
- Aftermarket CDI / ignition box (2-stroke) · Ignition
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
VSK.3.3
- Aftermarket cylinder (2-stroke) · Engine
Legal1 part
Stroke and rod length may be changed. VSK.3.4
Legal1 part
Intake and exhaust ports may be modified; diameters and shapes may be changed. VSK.3.2
Legal1 part
Titanium driveshaft, impeller housing or stator vane assemblies ARE permitted in Vintage Ski. This is the opposite of X2 and SC and worth verifying.
Legal1 part
VSK.2.7
- Aftermarket FIXED-position trim tab / ride plate extension · Hull and handling
Legal1 part
VSK.2.8
- Aftermarket handlepole / pole bracket · Hull and handling
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
VSK.2.3
- 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, VSK, read from the rulebook on 2026-09-07, not verified by a racer. Read the rule yourself, Vintage Ski. 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 · 45 permitted outright · 2025 rulebook