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Class Legality

IJSBA · runabout

Runabout Stock

IJSBA 2024, RAS. A closed-list class. The craft must stay stock except where the rules allow otherwise, so anything unlisted is not permitted.

  • 7Not legal
  • 12OEM part required
  • 12Not permitted, not listed in the rules
  • 1The rules do not say
  • 16Legal, with conditions
  • 12Legal

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
Watercraft must remain strictly stock except where the rules allow or require substitutions.
Displacement limit
Two-stroke: must not exceed the class designation, e.g. 550cc in 550 Stock, 850cc in 850 Stock (RAS.4.1). Four-stroke: no cc figure stated; boring permitted.
Licence or tier
Not stated.
Minimum weight
Four-stroke runabouts must weigh within no more than 35 lb (15.88 kg) lighter than OEM weight as determined by IJSBA.

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 (3)

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.

  • No eligible-model list, model years or homologation table in the document.
  • No rider age or licence class, no racing number rule, no numeric boost limit.
  • No separate ride plate article distinct from the pump cover plate.

What the rules say (60 parts)

12 permitted outright, 16 permitted with stated conditions, 7 refused by a rule we can quote, 12 held to the original part by a rule we can quote, 12 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.

Not legal1 part

No replacement cylinder is listed and no internal modification of any kind is allowed on any engine component, so a two-stroke cylinder may only be bored and have its ports chamfered up to 1.00mm (0.04 in.) at 30 degrees. RAS.4.1, RAS.4.4

OEM part required1 part

RAS.4.5 keeps a two-stroke exhaust system stock as supplied, with only a stinger insert, and RAS.3.8 lists no aftermarket manifold or head pipe for a four-stroke, allowing a manifold previously drilled or tapped once the holes are filled or capped, and flange removal. RAS.1.1, RAS.3.8, RAS.4.5

OEM part required1 part

Every portion of a four-stroke intake manifold must remain as originally equipped, and the two-stroke fuel section lists no manifold change. RAS.1.1, RAS.5.1

OEM part required1 part

Fuel injectors and fuel pump must remain stock as furnished by the manufacturer. RAS.5.3

OEM part required1 part

The fuel pump and fuel injectors must remain stock as furnished by the manufacturer, and the two-stroke fuel section lists no pump change either. RAS.1.1, RAS.5.3

OEM part required1 part

The original fuel tank, pickup, filler, filter, tap assembly and relief valve must be used unmodified, and only the filler cap may be modified or aftermarket. The held text prints this clause as 6.5.2 inside RAS.6, where the class numbering makes it RAS.6.2, and the four-stroke fuel section has no tank clause, so RAS.1.1 keeps a four-stroke tank stock as well. RAS.1.1, RAS.6.2

OEM part required1 part

The crankshaft must remain stock; replacement bearings or bearing shells are allowed if they keep their original type and dimensions. RAS.3.3

OEM part required1 part

Camshafts must remain stock; timing adjustment allowed. RAS.3.4

OEM part required1 part

No hood change is listed, and even the engine compartment ventilation tubes must remain as originally equipped, so the hood stays OEM. RAS.1.1, RAS.2.13

OEM part required1 part

The hull may be repaired but not otherwise modified, and a repair may not alter the original configuration by more than 2.00mm (0.08 in.). RAS.2.2

Not permitted, not listed in the rules10 parts

Not listed in this class document. Illegal under the closed-list principle.

Not permitted, not listed in the rules1 part

No aftermarket hull is listed, the craft must remain strictly stock, and a deck repair may not alter the original configuration by more than 2.00mm (0.08 in.). RAS.1.1, RAS.2.2

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

Clutches, belts and internal replacement parts need not be OEM provided they are IJSBA-APPROVED, and OEM gear ratios must be maintained. Shafts may be welded or reinforced FOR SAFETY PURPOSES only. RAS.9.2

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

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

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.

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

Aftermarket valve springs and valve spring retainers may be used. A later clause in the same four-stroke section allows them only when IJSBA approved. RAS.3.5, RAS.3.9

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, RAS, 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

“Runabout Stock, IJSBA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ijsba/runabout-stock/

Add the date you read it.

60 parts read · 12 permitted, 16 with conditions · 2024 rulebook

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