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Class Legality

IHRA · runabout

Runabout GP

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

  • 1Not legal
  • 2OEM part required
  • 10Not permitted, not listed in the rules
  • 31Legal, with conditions
  • 25Legal

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
All four-stroke watercraft, provided displacement stays within the division limit. No model-year list is published.
Displacement limit
1100cc in the 1100 division and 2000cc in the 2000 division (X.1). The section runs two divisions under one set of technical rules, an 1100cc Open/GP and a 2000cc Open/GP. X.2.1 permits aftermarket pistons and allows boring and stroke modifications within the displacement restrictions, so the figures are a ceiling on the engine as raced.
Licence or tier
Expert or Pro required (C.2). Minimum age 16 for any supercharged or turbocharged runabout (C.2.2).
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 (2)

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.

  • X.7.1 requires an upper deck to resemble the OEM version "as closely as possible" and settles disputes with a silhouette test it does not describe.
  • X.5.1 prints "Electronic Contril Unit". A transcription defect.

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 hull width figure, where Runabout GP2, GP3 and Limited all state 38 to 50 in.
  • No boost pressure ceiling.
  • No published list of approved aftermarket hulls.

What the rules say (69 parts)

25 permitted outright, 31 permitted with stated conditions, 1 refused by a rule we can quote, 2 held to the original part by a rule we can quote and 10 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

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

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 rules10 parts

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

Legal, with conditions1 part

Part of the exhaust system, which "including the manifold, connecting pipes, hoses, and mufflers, may be modified or replaced with aftermarket parts". Through-hull exhaust may be replaced if it creates no safety hazard, the tuned portion must not extend beyond the hull, and the exit may move to the transom below the bond flange. X.2.5

Legal, with conditions1 part

The class requires a flame arrester meeting USCG, UL-1111 or SAE J-1928 rather than the OEM one, so a compliant aftermarket arrester reads as allowed. X.3.2

Legal, with conditions1 part

May increase fuel flow but must not increase airflow into the chamber. Extra injectors allowed. X.3.5

Legal, with conditions1 part

Must be OE; replacements may come from another PWC if unmodified. Fully aftermarket only with Race Director or Technical Director approval. Filler and relief valve must remain OE unaltered. X.3.4

Legal, with conditions1 part

Gauges may be modified or removed provided no hazard is created and any resulting hole is sealed. Section J permits modification and removal and never addresses adding an aftermarket instrument. J.15

Legal, with conditions1 part

Replacement wiring is allowed under J.7, and this class also opens the ignition system and electrical box to modification or aftermarket parts and allows an aftermarket ECU, so wiring inside the electrical box and serving the ignition and ECU may change with them. The harness beyond those parts is held to J.7 replacement. J.7, X.5.1, X.5.2

Legal, with conditions1 part

Boring and stroke modifications allowed within displacement limits. X.2.1

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

Must originate from a production runabout watercraft. Only limitation is the cc limit. Interchanging top decks and engines permitted. X.2.7

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

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

Aftermarket hulls permitted if approved by the series organizer. Upper deck must resemble the OEM version as closely as possible. Silhouette test settles disputes. X.7.1

Legal, with conditions1 part

Sufficient flotation must be maintained. X.7.5

Legal, with conditions1 part

Ventilation tubes in the engine compartment may be altered, replaced with aftermarket options, repositioned on the original ducting or removed, with no opening-size limit stated, though covering or sealing a vent is not named. X.7.4

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

Legal1 part

Intake manifold assemblies may be aftermarket or modified, as X.3.1 and X.3.3 allow. X.3.1, X.3.3

Legal1 part

The flywheel and flywheel cover may be modified or aftermarket, as may the ignition system and electrical box, and the battery charging circuit may be disabled or removed entirely. X.5.2

Legal1 part

Boost sensors may be modified or replaced with aftermarket components, with no type or range limit, on the forced induction the class allows. X.4.3, X.4.1

Legal1 part

Aftermarket or modified connecting rods are allowed, with no material rule, and rod length may be changed. X.2.2

Legal1 part

Aftermarket camshafts are allowed and cam timing may be adjusted, with no limit on camshaft count or bearing type stated. X.2.8

Legal1 part

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

Legal1 part

Full circulating water-jacket housing required while running. May be added to an originally NA four-stroke. X.4.1

Legal1 part

Intercoolers may be modified or replaced with aftermarket units, with no size or type limit, on the forced induction the class allows. X.4.2, X.4.1

Legal1 part

The impeller may be modified or aftermarket along with the housing, stator vanes, mounting plate and nozzle. X.6.4

Legal1 part

The hood may be modified or replaced with an aftermarket one, provided no hazard is created. X.7.3

Legal1 part

The seat may be aftermarket or modified, subject to aftermarket seat guidelines that the rulebook cites but never prints. X.7.2

Legal1 part

The whole seat may be aftermarket or modified, which takes in the cover, subject to guidelines for aftermarket seats that the held text does not define. X.7.2

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, X, 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.

Cite this page

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

Add the date you read it.

69 parts read · 25 permitted, 31 with conditions · 2026 rulebook

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