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Class Legality

IHRA · ski

Ski 1500 Modified

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

  • 1Not legal
  • 5OEM part required
  • 24Not permitted, not listed in the rules
  • 26Legal, with conditions
  • 12Legal

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
Aftermarket hulls with OEM 1500 four-stroke engines, and stock or modified OEM hulls with OEM four-stroke engines. No model-year list is published.
Displacement limit
1500cc (Q.1). Non-turbo four-stroke engines only, a limit printed in the section Q introduction rather than in Q.1. Q.2.1 permits the engine to be bored and does not repeat the figure. Q.1 states it of the watercraft competing, so a craft bored past it stops meeting the class criteria.
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 (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.

  • Q.3.3 permits aftermarket fuel tanks, filters and petcocks and then requires in the next sentence that the fuel tank be OEM and not substituted with any other tank. The two sentences cannot both hold. The closed-list principle points at the stricter reading, and that is a reading rather than the rule.
  • Q.6.4 forbids modifying the inner hull liner or deck to facilitate foam removal. Ski Vintage at S.6.3 permits exactly that. The divergence is real and per-class, so no general foam answer is possible.

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 forced induction article, consistent with the non-turbo restriction in the class criteria.

What the rules say (68 parts)

12 permitted outright, 26 permitted with stated conditions, 1 refused by a rule we can quote, 5 held to the original part by a rule we can quote and 24 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

Must remain OEM. No modifications to the throttle plate or housing. Q.3.2

OEM part required1 part

Must remain OEM. The same rule first permits aftermarket tanks and then requires OEM, so this site reads it as OEM only. Q.3.3

OEM part required1 part

The original ECU must stay and may only be reprogrammed, on its original connections, with no input, output or sensor added, so an aftermarket or standalone box is not legal here. Q.4.1

OEM part required1 part

Must remain OEM. Timing may be altered. Adjustable timing sprockets may be installed. Q.2.3

Not permitted, not listed in the rules23 parts

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

Not permitted, not listed in the rules1 part

Q.2.5 lists no aftermarket manifold or head pipe and allows only the use of an OEM manifold previously drilled or tapped, with the holes properly sealed. A.2.2, J.1, Q.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. Q.3.1

Legal, with conditions1 part

Where no airflow sensor is fitted, the ducting between the flame arrester and the throttle body may be modified. The clause names no aftermarket ducting, gives nothing for an engine with a sensor and names no cold air system. Q.3.1

Legal, with conditions1 part

Reprogramming the original unit is the permitted route, on its original connections, with no input, output or sensor added. Q.4.1

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

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 retain the original compression ratio and profile, with no abrasive cleaning of the ports and piston weight within 25 per cent. Q.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

Replacements must match OEM weight and dimensions. Q.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

Aftermarket or modified. An extension may not exceed the width of the original plate, and on a ski may not extend more than 100 mm (3.94 in). J.18.1

Legal, with conditions1 part

Must maintain original handling characteristics. Q.5.1

Legal, with conditions1 part

Aftermarket hulls may be attached to OEM top decks within the class limits of 97 in length and 20 to 30 in width. A bow appendage is answered under hull extension. Q.1, Q.6.1

Legal, with conditions1 part

Flotation foam only. The inner hull liner or deck must NOT be modified to facilitate removal. Q.6.4

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. Q.6.3

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

Mat kits and padding are allowed in every class by the general rules (J.14), which overrides the closed-list default. Footholds and foot straps are not named there, so they stay not permitted. J.14

Legal, with conditions1 part

The handle pole assembly and mounting brackets may be modified or replaced provided original functionality is retained. Length may be altered and the attaching point reinforced. J.17.2

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

A modified OEM hull is eligible if it meets the class limits of 97 in maximum length and a width between 20 and 30 in. Q.1

Legal, with conditions1 part

A bow appendage that diverts spray and stabilises the craft may be added if approved and built to the original specifications. Any other extension is a modification of the OEM hull, which the class admits within its 97 in maximum length. Q.1, Q.6.1

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

Aftermarket impellers are allowed alongside aftermarket housings, stator vanes, mounting plates and pump shoes, with no diameter or pitch limit stated. Q.5.3

Legal1 part

Aftermarket top decks may be used, and an aftermarket hull may be fitted to an OEM deck, with any bow appendage kept to original specifications and approved. Q.6.1

Legal1 part

Aftermarket hoods are allowed, provided they comply with the rulebook safety and handling regulations. Q.6.2

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 engine cooling system may be modified and extra cooling lines or bypass fittings added, provided nothing creates a hazard and outlets are directed away from other competitors. Q.2.4

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, Q, 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

  • Footholds, foot straps and tray mats. Corrected 2026-10-02: the Ski 1500 Modified row read the closed-list default and refused a mat kit, which J.14, in the general rules for all classes, allows.
  • High-pressure fuel line and fittings. Corrected 2026-10-02: the Ski 1500 Modified 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.
Cite this page

“Ski 1500 Modified, IHRA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ihra/ski-1500-modified/

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68 parts read · 12 permitted, 26 with conditions · 2026 rulebook

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