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Class Legality

IJSBA · sport

Sport Spec

IJSBA 2024, section headings, no numbered rules. A closed-list class. The craft must stay stock except where the rules allow otherwise, so anything unlisted is not permitted.

  • 4Not legal
  • 2OEM part required
  • 2Not permitted, not listed in the rules
  • 1The rules do not say
  • 30Legal, with conditions
  • 13Legal

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

Displacement limit
Bore limit: all spec-eligible engines may be bored a maximum of 1mm. The IJSBA Displacement Guide gives: 850cc for two-stroke engines, no other engines permitted. Kawasaki first-generation upgrade paths, update to a Kawasaki 750 or 800cc engine with electronics and follow IJSBA Open class rules and upgrade to a Kawasaki 900 or 1100cc motor.
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.

Open questions on this class (6)

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.

  • This document uses capitalised section headings rather than numbered rules, so answers here cite the heading, not a rule number.
  • 2024 document, may have been superseded for 2025.
  • The Model Homologation listing on pages 10-11 did not come through and should be retrieved separately.
  • A pre-launch note on the WaveBlaster in this class was supplied on 2026-09-10 and is held by this project rather than published. It is NOT this rulebook, it cites APBA limits where this document cites none, and it predates the class in its own words. Its 1mm overbore limit matches this record exactly, which is either the idea surviving into the sanctioned rules or the note being closer to IJSBA than its APBA references suggest. Unattributed, so nothing from it is published.
  • Polaris Hurricane displacement ceiling is not stated.
  • The four-sponson allowance is unusual relative to the other two Sport/Freestyle classes.

What the rules say (52 parts)

13 permitted outright, 30 permitted with stated conditions, 4 refused by a rule we can quote, 2 held to the original part by a rule we can quote, 2 refused by our reading of the class rather than by a quoted rule and 1 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.

OEM part required1 part

Flywheels must be OEM stock and unmodified as supplied from the factory. Sea-Doo HX must use the OEM unmodified 720 flywheel.

Not permitted, not listed in the rules1 part

The class admits the Kawasaki X2, which has a handle pole, and does not list the pole. It opens the handlebar, throttle, cable and grips, the steering shaft and its holder, and the handlebar holder, and changes not listed are not permitted. A Gen 1 X2 entered under Option 1 or 2 follows IJSBA Open class rules, which no held text defines; the other eligible craft have fixed handlebars.

Legal, with conditions1 part

Kawasaki, Yamaha and Polaris may relocate and replace the chamber. Sea-Doo HX must retain the unmodified stock HX exhaust. Wet-style only; dry pipes and water-jacketed chambers prohibited.

Legal, with conditions1 part

Kawasaki, Yamaha and Polaris may relocate and replace with aftermarket. Sea-Doo HX must use an OEM factory HX waterbox with water fittings plugged.

Legal, with conditions1 part

Polaris Hurricane and Yamaha Waveblaster carburetors may be modified or aftermarket. SEA-DOO HX MUST RETAIN STOCK CARBURETORS (rejetting and de-choking only).

Legal, with conditions1 part

Allowed on Polaris Hurricane, Kawasaki X2 05-07 and Yamaha Waveblaster. Sea-Doo HX must keep the OEM manifold with factory line connections aligned as from the factory.

Legal, with conditions1 part

Yamaha CDI modified or aftermarket provided timing is NOT manually adjustable. Kawasaki Gen 2 (2005-2007) CDI may be programmable. Advancing timing at the stator plate is prohibited on every model.

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

Yamaha Waveblaster may upgrade to 701 62T-style cylinders; Yamaha 760 cylinders allowed subject to ignition restrictions; pre-1996 Yamaha may update to 1996+ components. Max 1mm overbore across the board.

Legal, with conditions1 part

Compression capped: Kawasaki and Yamaha max 190 psi with min 0.040 in squish; Sea-Doo HX max 175 psi with min 0.051 in squish. Drop-down style domes prohibited on all models.

Legal, with conditions1 part

Must retain original port timing, dome profile, skirt length/shape and material type, and weigh within +/-5.00% of OEM. Note this is 5%, tighter than the 25% used elsewhere.

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

Up to FOUR. Single- or two-sponson configuration per side limited to 1,524mm.

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

Ventilation tubes may be modified, relocated or removed. Polaris Hurricane hood/mirror cowling may be replaced provided it creates no additional airflow. NO OTHER hood modifications permitted.

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.

Legal, with conditions1 part

Repairs may move the hull no more than 2.00mm (0.08 in.) from its standard configuration, the hull may be reinforced internally, and a Kawasaki Gen 1 X2 (pre 2005) may add front hull fills reaching no more than 36 in back from the bow.

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.

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

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 2024, section headings, no numbered rules, 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

“Sport Spec, IJSBA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ijsba/sport-spec/

Add the date you read it.

52 parts read · 13 permitted, 30 with conditions · 2024 rulebook

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