Not legal1 part
No titanium driveshaft, impeller housing or stator vane assembly may be used. VSC.6.1
IJSBA · vintage
Vintage SC
IJSBA 2022, VSC. A closed-list class. The craft must stay stock except where the rules allow otherwise, so anything unlisted is not permitted.
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
- Kawasaki SC. The hull must be EXCLUSIVELY the 1991 OEM SC hull.
- Displacement limit
- 850cc. VSC.3.1 permits the engine to be bored and requires the displacement not to exceed the class designation, and records 850cc as the maximum allowed at the IJSBA World Finals.
- Licence or tier
- Not stated.
- 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.
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.
- Oldest of the four Vintage documents (2022) and may have been superseded.
- The hull is stated as "1991 OEM SC" only. Whether other SC model years or the 750SC qualify is NOT addressed and must not be inferred.
- No handlebar padding requirement surfaced, unlike Vintage Ski and X2.
What the rules say (51 parts)
29 permitted outright, 17 permitted with stated conditions, 3 refused by a rule we can quote, 1 held to the original part by a rule we can quote and 1 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 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.
- 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
Manual or automatic trim tabs attached to the hull or ride plate are prohibited. VSC.2.7
- Rider-controlled or automatic trim tab system · Hull and handling
Not legal1 part
Exclusively the 1991 OEM SC hull.
- Aftermarket hull or top deck · Hull and handling
OEM part required1 part
The 1991 SC hull stays as the manufacturer furnished it, and only the deck may be reinforced internally. VSC.2.2
- Modification of the OEM hull · Hull and handling
Not permitted, not listed in the rules1 part
Only the flywheel cover is listed, and VSC.5.3 lets it be modified to accept a crankshaft-end bearing support; VSC.5.1 keeps the original equipment charging system and allows no other ignition modification. VSC.1.1, VSC.5.1, VSC.5.3
- Aftermarket or lightened flywheel · Ignition
Legal, with conditions3 parts
Permitted, subject to the limits IJSBA applies to every class, namely the sound ceiling, the hull repair tolerance, and the intake grate and sponson dimensions.
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. VSC.3.7
- Stinger reducer insert + cooling line · Exhaust
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.
- Replacement battery · Electrical
Legal, with conditions1 part
The clause opens the impeller housing the ring lines to modified or aftermarket parts but bars a titanium housing, so a titanium ring is out with it. VSC.6.1
- Replacement wear ring · Driveline
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.
- Aftermarket pump cover plate / extension · Driveline
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.
- Aftermarket intake grate · Driveline
Legal, with conditions1 part
Max TWO. Max 63.5mm drop.
- Aftermarket sponsons · Hull and handling
Legal, with conditions1 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, with conditions1 part
Seat covers and assemblies modified or aftermarket, with seat height no more than 3 in above original.
- Aftermarket seat assembly / seat base · Hull and handling
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.
- Footholds, tray mats, padding kits · Hull and handling
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.
- Replacement bumpers and water-spray deflectors · Hull and handling
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
Fixed-type or automatic valves only. Thermostats, pressure regulators and solenoids qualify. Manual actuation of any kind during operation is prohibited everywhere.
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.
- Ballast weight kits · Hull and handling
Legal, with conditions1 part
An extension mounted on the transom counts as a trim tab, so it must be fixed in position, no wider than the planing surface and no more than 100.00mm (3.94 in.) past the end of the original planing surface, as on the fixed trim tab row. VSC.2.7
- Hull extension · Hull and handling
Legal3 parts
Manifold, head pipe, expansion chamber, waterbox and muffler modified or aftermarket. VSC.3.7
- Aftermarket expansion chamber / tuned pipe (2-stroke) · Exhaust
- Aftermarket exhaust manifold / head pipe · Exhaust
- Aftermarket waterbox · Exhaust
Legal2 parts
Reed valve assemblies modified or aftermarket. VSC.4.6
Legal2 parts
The cylinder and cylinder head may be modified or aftermarket. VSC.3.3
- Aftermarket cylinder (2-stroke) · Engine
- Aftermarket cylinder head (2-stroke) · Engine
Legal1 part
Through-hull exhaust modified or aftermarket; exit may be relocated to the transom below the bond flange. VSC.3.7
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. VSC.4.1
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. VSC.4.1
Legal1 part
Intake manifold assembly may be modified or aftermarket. VSC.4.1
- 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
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
The CDI unit may be modified or aftermarket, ignition timing changed and the ignition pickup mount modified, while the original equipment charging system must stay. VSC.5.1
- 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
Engines may be bored and aftermarket piston assemblies are allowed, with displacement kept within the class limit. VSC.3.1
- Aftermarket piston assemblies · Engine
Legal1 part
Stroke and rod length may be changed. VSC.3.4
Legal1 part
The crankshaft assembly may be modified or aftermarket and rod length may be changed, which covers the connecting rods. VSC.3.4
- Aftermarket connecting rods · Engine
Legal1 part
Intake and exhaust ports may be modified; diameters and shapes may be changed. VSC.3.2, VSC.3.3
Legal1 part
The cylinder may be modified or aftermarket and port diameters and shapes may be changed, so a chamfer within the appendix limit is covered. VSC.3.2, VSC.3.3
Legal1 part
The impeller may be modified or aftermarket, and the clause sets no diameter limit. VSC.6.1
- Aftermarket impeller at OEM diameter · Driveline
Legal1 part
The impeller housing, stator vane assembly, pump mounting plate and pump shoe may be modified or aftermarket but not in titanium, and the complete pump and nozzle assembly may be no more than 50.00mm (1.97 in.) longer than original. VSC.6.1
Legal1 part
The driveline clause allows aftermarket nozzle trim systems. VSC.6.2
- Aftermarket nozzle trim system (pump-mounted) · Driveline
Legal1 part
Aftermarket fixed-position trim tabs may be used, no wider than the planing surface and reaching no more than 100.00mm (3.94 in.) past its end. VSC.2.7
- Aftermarket FIXED-position trim tab / ride plate extension · 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
An aftermarket hood may be used. The ventilation tube clause still allows no other modification to the hood, so the original hood cannot be reworked beyond its vents. VSC.2.3, VSC.2.13
- 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 2022, VSC, read from the rulebook on 2026-09-07. Read the rule yourself, Vintage SC. 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.
- Replacement wear ring. Corrected 2026-10-01: this row read as unanswered until VSC.6.1 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 VSC.3.7 was read against it, and the clause opens the whole exhaust system.
Cite this page
“Vintage SC, IJSBA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ijsba/vintage-sc/
Add the date you read it.
51 parts read · 29 permitted, 17 with conditions · 2022 rulebook