Not legal1 part
Relocating the exhaust is prohibited and the exit opening may not exceed 2 inches. VSKL.3.7
IJSBA · vintage
Vintage Ski Limited
IJSBA 2025, VSKL. 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
- Original Kawasaki 550 engine cases must be used. Hull and top deck must remain as originally furnished by the manufacturer.
- Displacement limit
- 558cc. Fixed geometry: 110mm rods and 60mm stroke only - stroke and rod length changes prohibited. VSKL.3.1 permits the engine to be bored and requires the displacement not to exceed 558cc, so the figure is a ceiling on the engine as raced and not only as the factory built it.
- 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.
- The class is BOTH a closed list AND inherits Stock Class provisions. Areas silent here (ride plate, seat, footwells, racing numbers, fuel pumps, vapor separators, fuel injection) are most likely governed by the Stock Class rules in a separate document, so silence here is not permission.
- No model-year cutoff appears, so which 550s qualify by year is not stated.
- The exhaust section mentions "Two-Stroke/Four-Stroke Runabout Limited", suggesting shared boilerplate that may not be intended for this craft.
- Whether aftermarket hoods and modifiable impeller housings are legal via Stock Class inheritance is the single most commercially significant open question for this class.
What the rules say (51 parts)
13 permitted outright, 18 permitted with stated conditions, 5 refused by a rule we can quote, 4 held to the original part by a rule we can quote, 7 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
Original port timing must be retained. Chamfer only.
Not legal1 part
NO AFTERMARKET SPONSONS ARE PERMITTED. OEM sponsons may be removed. VSKL.2.3
- Aftermarket sponsons · Hull and handling
Not legal1 part
Hull and top deck must remain as originally furnished.
- Aftermarket hull or top deck · Hull and handling
Not legal1 part
No trim tab or extension clause appears in the class, and VSKL.2.2 keeps the hull as the manufacturer furnished it, so nothing may be added beyond the pump cover plate extension on its own row. VSKL.2.2
- Hull extension · Hull and handling
OEM part required1 part
OE filler and relief valve required, unmodifiable. No tank replacement listed.
OEM part required1 part
CDI UNIT MUST REMAIN OEM. No aftermarket CDI, no timing changes, no total-loss ignition. VSKL.5.1
- Aftermarket CDI / ignition box (2-stroke) · Ignition
OEM part required1 part
CYLINDER MUST REMAIN OEM with original port timing. No internal modification of any kind. VSKL.3.1, VSKL.3.5
- Aftermarket cylinder (2-stroke) · Engine
OEM part required1 part
No hull work is listed: the hull and top deck stay exactly as the manufacturer furnished them. VSKL.2.2
- Modification of the OEM hull · Hull and handling
Not permitted, not listed in the rules3 parts
Not listed in this class document. Illegal under the closed-list principle.
- Stinger reducer insert + cooling line · Exhaust
- Aftermarket nozzle trim system (pump-mounted) · Driveline
- Rider-controlled or automatic trim tab system · Hull and handling
Not permitted, not listed in the rules1 part
VSKL.3.7 lists manifold, head pipe and expansion chamber only. Waterbox is not listed.
- Aftermarket waterbox · Exhaust
Not permitted, not listed in the rules1 part
Only the flywheel cover is listed, and VSKL.5.3 lets it be modified to accept a crankshaft-end bearing support; VSKL.5.1 keeps the original equipment charging system and allows no other ignition modification. VSKL.1.1, VSKL.5.1, VSKL.5.3
- Aftermarket or lightened flywheel · Ignition
Not permitted, not listed in the rules1 part
NOT listed as modifiable in VSKL. Under the closed-list rule these must remain OEM. Flagged as a commercially significant open question.
Not permitted, not listed in the rules1 part
Aftermarket hoods are NOT listed as permitted. Under VSKL.2.2 and the closed-list rule the hood should be treated as OEM-required. This is a direct contrast with the other three Vintage classes. Whether VSKL.1.1's allowance of Stock Class provisions brings it back in is flagged as a commercially significant open question.
- Aftermarket hood / engine cover · Hull and handling
The rules do not say1 part
Not stated in the Vintage Ski Limited rules. VSKL.1.1 carries the Stock class provisions into this class unless one of its own rules says otherwise, so the answer is the Stock one. VSKL.1.1
The rules do not say1 part
Not addressed in this class document.
- Replacement wear ring · Driveline
The rules do not say1 part
No titanium prohibition stated, but no permission either. Titanium FASTENERS are prohibited unless originally equipped.
The rules do not say1 part
Not addressed. Treat as OEM only unless Stock Class provisions permit otherwise.
- Aftermarket FIXED-position trim tab / ride plate extension · Hull and handling
Legal, with conditions2 parts
Manifold, head pipe and expansion chamber allowed, but exhaust may NOT be relocated and the exit opening may not exceed 2 inches. VSKL.3.7
Legal, with conditions1 part
ONLY ONE SINGLE CARBURETOR IS PERMITTED. VSKL.4.1
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
Within +/-25.00% of OE weight; original port timing, compression ratio, dome profile and skirt retained.
- Aftermarket piston assemblies · Engine
Legal, with conditions1 part
Rebuild only. 110mm rods and 60mm stroke ONLY. +/-5.00% assembly weight. Replacement counterweights must resemble the original. Non-ferrous prohibited.
Legal, with conditions1 part
Ferrous only; 110mm rods only.
- Aftermarket connecting rods · Engine
Legal, with conditions1 part
The only Vintage class with an explicit numeric chamfer limit. VSKL.3.1
Legal, with conditions1 part
Max 50.00mm over OEM. VSKL.6.1
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
HANDLEPOLE MUST REMAIN OEM. Only the BRACKET may be aftermarket, and the attaching point may be reinforced. VSKL.2.8
- Aftermarket handlepole / pole bracket · 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
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
Legal2 parts
Reed valve assemblies modified or aftermarket. VSKL.4.6
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. VSKL.4.1
Legal1 part
Intake manifold assembly may be modified or aftermarket. VSKL.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
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
The cylinder HEAD may be modified or aftermarket even though the cylinder may not. VSKL.3.6
- Aftermarket cylinder head (2-stroke) · Engine
Legal1 part
The impeller may be modified or aftermarket, and the clause sets no diameter limit. VSKL.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
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, VSKL, read from the rulebook on 2026-09-07. Read the rule yourself, Vintage Ski Limited. 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
“Vintage Ski Limited, IJSBA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ijsba/vintage-ski-limited/
Add the date you read it.
51 parts read · 13 permitted, 18 with conditions · 2025 rulebook