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Runabout Limited

IHRA · runabout

Runabout Limited

IHRA2026, BB. A closed-list class. The craft must stay stock except where the rules allow otherwise, so anything unlisted is not permitted.

Open questions on this class (4)

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.

  • BB.2.2 requires four-stroke counterweights, stroke and rod lengths to remain as the manufacturer specified and, next to it, permits aftermarket or modified crankshafts and connecting rods within 5 per cent of OEM weight. Both sentences stand and neither is discardable.
  • BB.7.4 permits an air fuel ratio gauge on the exhaust and forbids connecting it to the ECU or to any automatic tuning device. Whether a logger that writes to a card counts as an automatic tuning device is not addressed.
  • BB.2.9 forbids titanium valve components unless originally equipped, restating the general J.7 fastener rule in a different place with a different scope.
  • BB.3.5 requires any cylinder or crankcase modification to be approved and names no approver.

Sections this rulebook does not contain for this class

Confirmed absent by a targeted read rather than merely unnoticed. In a closed-list class an absent article is why a part reads as not permitted; in an open class it is why one reads as open.

  • No eligible model list, unusually for a Limited class.
  • No general hull article. Hull work reaches this class only through the foam rule at BB.10.4.

What the rules say (77 parts)

50 permitted outright, 23 answered by our reading of the class rather than by a quoted rule, 0 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 permitted, not listed in the rulesOur reading, not a rule we can quote at you. This class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list.

Not legal1 part

Bolts, nuts and washers may not be substituted with titanium unless originally equipped. Locking mechanisms are allowed. J.7

OEM part required1 part

Must remain OEM. Four-stroke entries: No modifications to throttle plate angles or housing. BB.4.3

OEM part required1 part

On four-stroke entries the original ECU must stay and may only be reprogrammed, with no additional input or output, so an aftermarket or standalone box is not legal here. BB.7.1

Not permitted, not listed in the rules23 parts

On a closed list an unlisted modification is not permitted. A.2.2, J.1

Legal, within limits3 parts

Model-dependent. On four-stroke entries removal of the plastic resonator is permitted (BB.2.6). On two-stroke entries the manifold, head pipe, expansion chamber, gaskets and the hose to the OEM water box may be aftermarket, the exhaust gas location may not be relocated, the original opening size must be kept, THE ORIGINAL WATER BOX IS REQUIRED AND UNMODIFIED, and no tuned portion may sit outside the hull. BB.3.4

Legal, within limits2 parts

Four-stroke entries: IMPELLER HOUSING MUST REMAIN OEM. Internals, pulleys, tensioners, intercoolers may be aftermarket. Spacers allowed for a larger impeller. Oil line fitting may be added to the shaft. BB.6.1

Legal, within limits1 part

Airflow sensor and turbo/supercharger system must remain unmodified. BB.4.1

Legal, within limits1 part

Four-stroke entries: A fuel return line must be installed for safety. BB.4.5 Two-stroke entries: Automatic shutoff. Manual pumps prohibited. Limits: max 4 psi. BB.5.5

Legal, within limits1 part

On four-stroke entries reprogramming the original unit is the permitted route, with no additional input or output. BB.7.1

Legal, within limits1 part

AFR gauges may be installed on the exhaust but must NOT be connected to the ECU or any automatic tuning device. BB.7.4

Legal, within limits1 part

Must fit the OE box. Two-stroke relocation only when necessary for an aftermarket exhaust. BB.8.3

Legal, within limits1 part

Four-stroke entries: Limits: weight tolerance 25 per cent. BB.2.1 Two-stroke entries: Cylinders may be machined to accommodate girdle-system heads. Limits: weight tolerance 25 per cent. BB.3.1

Legal, within limits1 part

Model-dependent. On four-stroke entries counterweights, stroke and rod lengths remain as the manufacturer specified and weight stays within 5 per cent, and the source text is internally tense, see KB section 9 (BB.2.2). On two-stroke entries no non-ferrous metals, stroke and rod length unchanged, counterweights resembling the original with no added holes or pockets, and assembly weight within 5 per cent. BB.3.2

Legal, within limits1 part

Repairs are allowed for a crack or puncture, but only one damaged area affecting one cylinder bank. No other modification. J.11

Legal, within limits1 part

Four-stroke entries: TITANIUM COMPONENTS NOT ALLOWED unless originally equipped. BB.2.9

Legal, within limits1 part

May be modified or replaced with an aftermarket part. The original diameter must be maintained in Stock class, and the rulebook never defines which classes that is. J.18.2

Legal, within limits1 part

May be replaced within OEM specifications. J.18.3

Legal, within limits1 part

Aftermarket or modified, full-length type with at least one bar parallel to the driveshaft, dropping no more than 12.00mm (0.47 in) below the flat plane of the pump intake. J.18.1

Legal, within limits1 part

Replacement trim plates may be used provided they mimic the handling characteristics of the stock plates. J.18.2

Legal, within limits1 part

Aftermarket fixed-position tabs only, with manual or automatic tabs attached to the hull prohibited, extending no more than 100 mm. BB.9.2

Legal, within limits1 part

Braking devices may be disabled for safety, and reverse buckets and trim motors may be removed or modified to disable them, provided no hazard is created. J.18.4

Legal, within limits1 part

Sea-Doo X4 type hulls: Aftermarket hoods permitted for Sea-Doo X4 type hulls ONLY. BB.10.3

Legal, within limits1 part

The inner hull liner or deck cannot be modified to facilitate foam removal. BB.10.4

Legal, within limits1 part

Aftermarket, modified, repositioned or removed. Up to two, each no longer than 36 in (91.45 cm), protruding no more than 3.94 in (100 mm) horizontally, at least 6 mm thick with radiused leading edges, and not attached to a planing surface. J.16

Legal, within limits1 part

Replacement bumpers and side rails may be used provided they create no hazard. A permanently affixed nose bumper remains required. J.13, I.17

Legal, within limits1 part

May be added to adjust handling. Constant mass only, and no other part may be modified to carry it. J.19

Legal, within limits1 part

OEM intercooler assemblies must remain in stock class. Volume changes to OEM water supply fittings prohibited. No fittings may be added to the cylinder head, cylinder, or crankcase. BB.2.4

Legal1 part

May be replaced, as may starters and oil injection systems, with the oil injection system removable or disconnectable. J.8

Legal1 part

Grips, throttle and cables may be modified or aftermarket. The bar must be padded at the mounting bracket or the crossbar padded. J.17.1

Legal1 part

Steering shaft, holder, handlebar holder and cables may be aftermarket, and quick-turn modifications are allowed. J.17.2

Legal1 part

The bilge pump may be modified or disconnected and aftermarket bilge draining systems are permitted, provided they create no hazard. J.10

IHRA 2026, BB, read from the rulebook on 2026-09-11, not verified by a racer. Read the rule yourself. Every IHRA 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.

77 parts read · 50 permitted outright · 2026 rulebook

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