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Class Legality

IHRA · runabout

Runabout Limited

IHRA 2026, BB. A closed-list class. The craft must stay stock except where the rules allow otherwise, so anything unlisted is not permitted.

  • 2Not legal
  • 6OEM part required
  • 17Not permitted, not listed in the rules
  • 36Legal, with conditions
  • 18Legal

Read out of the published IHRA rulebook on 2026-09-11, so confirm anything that decides a purchase. The full note is at the foot of the page.

Running the class

Eligible craft
The class criteria state hull dimensions, displacement ceilings by engine type and a sound limit, and name no models. No model-year list is published.
Displacement limit
800cc two-stroke, 1100cc naturally aspirated four-stroke and 2000cc forced-induction four-stroke (BB.1). BB.2.1 permits the engine to be bored and requires the displacement not to exceed the class designation, so the figures are a ceiling on the engine as raced.
Licence or tier
Not stated.
Minimum weight
Not stated.

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 (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 (79 parts)

18 permitted outright, 36 permitted with stated conditions, 2 refused by a rule we can quote, 6 held to the original part by a rule we can quote and 17 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

BB.3.4 states that the exhaust gas location cannot be relocated and the original size opening for the exhaust exit must be maintained; only the through-hull outlet flap and the plastic resonator may be removed. BB.3.4

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

OEM part required1 part

BB.6.1 keeps the impeller housing OEM and BB.4.1 keeps any turbocharger system unmodified, so a turbocharged entry keeps its original unit, and no aftermarket turbocharger is listed. J.1, BB.4.1, BB.6.1

OEM part required1 part

BB.6.1 keeps the impeller housing OEM, so the supercharger itself stays the original unit. Its internals, pulleys, tensioners and intercoolers may be aftermarket or modified and a spacer may fit a larger impeller, which makes it a modified OEM supercharger, not an aftermarket one. J.1, BB.6.1

OEM part required1 part

The hull may be repaired but not otherwise modified, and a repair may not move it more than 2 mm (0.08 in) from its original configuration. J.1, J.13

Not permitted, not listed in the rules17 parts

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

Legal, with conditions2 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, with conditions2 parts

Model-dependent. A two-stroke entry may run modified or aftermarket carburetors with no more venturis than cylinders and no slide type, while a four-stroke entry may only replace the jets, needle valves and needle springs and remove the choke. BB.4.2, BB.5.1

Legal, with conditions1 part

Model-dependent. Two-stroke entries may run modified or aftermarket intake manifold assemblies under BB.5.1, while the four-stroke rules in BB.4 name no manifold, so a four-stroke entry keeps its own. BB.4, BB.5.1, J.1

Legal, with conditions1 part

Four-stroke entries need a flame arrester meeting USCG or SAE standards and carbureted ones an arrester meeting safety standards, while two-stroke entries may fit an aftermarket arrester meeting USCG, SAE J-1928 or UL-1111. BB.4.1, BB.4.2, BB.5.3

Legal, with conditions1 part

The ducting between the flame arrester and the throttle body may be modified, but the airflow sensor and any turbocharger system stay unmodified, and no cold air system is named. BB.4.1

Legal, with conditions1 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, with conditions1 part

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

Legal, with conditions1 part

On a two-stroke entry BB.8.1 permits ignition timing adjustment and modification of the original ignition pickup mount, while the original charging system stays. BB.8.1

Legal, with conditions1 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, with conditions1 part

J.7, in the general rules for every class, names wiring as replaceable with aftermarket options, which overrides the closed-list default and covers replacement wiring. Connectors are not named on their own, and J.7 does not open added inputs or outputs, a different harness design or an ECU. J.7

Legal, with conditions1 part

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

Legal, with conditions1 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, with conditions1 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 rulebook's wording here pulls both ways (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, with conditions1 part

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

Legal, with conditions1 part

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

Legal, with conditions1 part

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, with conditions1 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, with conditions1 part

May be replaced within OEM specifications. J.18.3

Legal, with conditions1 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, with conditions1 part

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

Legal, with conditions1 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, with conditions1 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, with conditions1 part

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

Legal, with conditions1 part

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

Legal, with conditions1 part

Ventilation tubes may be altered, aftermarket, repositioned on the original ducting or removed, but inlet and outlet openings keep stock size, and vents may be covered or sealed with no other hood change, cover or cowling. BB.10.2

Legal, with conditions1 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, with conditions1 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, with conditions1 part

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

Legal, with conditions1 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

J.7, in the general rules for every class, names hoses and clamps as replaceable with aftermarket options, which overrides the closed-list default and covers an aftermarket fuel hose. Fittings are not named on their own. J.7

Legal1 part

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

Legal1 part

Intercoolers may be aftermarket or modified on four-stroke entries under BB.6.1. BB.6.1

Legal1 part

The seat may be aftermarket or modified, subject to aftermarket seat guidelines that the rulebook cites but never prints. BB.10.1

Legal1 part

Seat covers can be replaced, and the seat assembly may be aftermarket or modified, subject to guidelines for aftermarket seats that the held text does not define. BB.10.1

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. Read the rule yourself. Every IHRA 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.

What we corrected here, and when

  • High-pressure fuel line and fittings. Corrected 2026-10-02: the Runabout Limited row read the closed-list default and refused a fuel hose, which J.7 allows in every class; until 2026-10-31 this line wrongly excepted the drag section, where J.7 applies too.
  • Relocated or aftermarket through-hull outlet. Corrected 2026-09-30, Runabout Limited: the cell had been graded from a note about the resonator.
Cite this page

“Runabout Limited, IHRA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ihra/runabout-limited/

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79 parts read · 18 permitted, 36 with conditions · 2026 rulebook

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