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Class Legality

IHRA · ski

Ski GP

IHRA 2026, K. 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
  • 11Not permitted, not listed in the rules
  • 35Legal, with conditions
  • 19Legal

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 four-stroke engines, and modified OEM hulls with four-stroke engines. No model-year list is published.
Displacement limit
1500cc naturally aspirated and 1100cc forced induction (K.1). K.2.1 permits pistons to be replaced or bored while the engine displacement limits are held to, so the figures are a ceiling on the engine as raced and not only as the factory built it.
Licence or tier
Expert or Pro required (C.2). Minimum age 16 (C.2.2), with a written exception possible at 14 or older.
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.

  • The rulebook refers to hulls "approved by the Race Committee and IHRA" at K.8.1 and never publishes that list. No claim that a named aftermarket hull is eligible here can be sourced to this document.
  • K.6.1 prints "Electronic Contril Unit". A transcription defect in the source, not a different part.

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 sound limit. K.1 states hull length, width, displacement and eligible craft and stops. Fifteen of the nineteen non-drag class sections print 86 dB(a) at 75 feet and this is one of the four that does not.
  • No minimum weight.
  • No boost pressure ceiling, where the comparable Sport GP class states two.

What the rules say (68 parts)

19 permitted outright, 35 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 11 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

Not permitted, not listed in the rules1 part

K.7.2 lets the OEM impeller, pump housing, stator, mounting plate and pump shoe be modified, with the pump and nozzle assembly up to 50 mm longer than OEM, but it names no aftermarket housing or stator, although K.2.4 and K.5.1 in the same section say aftermarket in terms. Under J.1 a replacement part must be expressly allowed, and K.7.2 allows modification only. A.2.2, J.1, K.7.2

Not permitted, not listed in the rules1 part

K.7.2 does not name the pump nozzle among the parts it opens to modification, and lists an aftermarket nozzle trim system, a steering part, rather than an aftermarket nozzle. Its 50 mm allowance on overall pump and nozzle length can be met through the housing, mounting plate or shoe, and boring is not listed here as it is in Ski GP3 at M.6.1.3. A.2.2, J.1, K.7.2

Legal, with conditions1 part

Part of the exhaust system, which "including the manifold, pipes, hoses, and mufflers, may be modified or replaced with aftermarket parts"; the exhaust exit may be relocated to the transom. Section K never keeps the water box OEM, as the restrictive classes do in terms. K.2.5, K.3.5

Legal, with conditions1 part

May increase fuel flow but must not enhance airflow into the chamber. Extra injectors allowed. K.4.3

Legal, with conditions1 part

The pump must stop automatically when the engine stops, and manual on/off pumps are prohibited. K.4.3

Legal, with conditions1 part

Must be an unmodified tank from another watercraft. Non-OEM tanks only with Technical Director approval meeting OEM strength and safety. K.4.2

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, K.6.1, K.6.2

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

1101cc+: blocks interchangeable across any OEM manufacturer EXCEPT the 1500cc Kawasaki SX-R which must use the manufacturer's block. 1100cc and below (K.3.6): donor block must be 1100cc or less. K.2.6

Legal, with conditions1 part

Original activation method must be maintained. K.2.7

Legal, with conditions1 part

Engines of 1100cc or less only, with a water-jacketed housing required, and it may be added to a craft that was naturally aspirated as built. K.5.1

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

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

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

Legal, with conditions1 part

Aftermarket hulls permitted subject to Race Committee and IHRA approval. No fins, rudders, or skegs. Must not exceed the length or width of the upper deck bond flange by plumb bob. K.8.1

Legal, with conditions1 part

Only engine-compartment flotation foam. K.8.4

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. K.8.3

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 (J.14), and the hull may be altered to take legal aftermarket footholds (K.8.1). Footwells must be blocked off during competition. J.14, K.8.1, K.8.5

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

The OEM hull may be modified while it stays inside the length and width of the upper deck's bond flange measured by plumb bob, bumpers excluded, and it may carry no fins, rudders or skegs. A separated bond flange must be rejoined by the original method, such as high-strength adhesive. K.1, K.8.1, K.8.5

Legal, with conditions1 part

No Ski GP clause names an extension, so one counts as hull modification and must stay inside the plumb-bob outline of the upper deck bond flange without fins, rudders or skegs. Trim tabs, on their own row, may reach 100 mm (3.94 in) past the original planing surface. K.8.1, K.7.1

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. K.6.2, K.6.3

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. K.5.3, K.5.1

Legal1 part

Pistons may be replaced or bored, aftermarket ones included, provided engine displacement stays within the class limit. K.2.1, K.3.1

Legal1 part

Camshaft count unchanged; original bearing type and dimensions. K.2.3

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 modified or replaced with aftermarket units, with no size or type limit, on the forced induction the class allows. K.5.2, K.5.1

Legal1 part

Aftermarket hoods are allowed, with no shape or material limit stated. K.8.2

Legal1 part

Aftermarket bulkheads are permitted, with no material or design limit stated. K.8.1, K.8.5

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, K, 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 GP row said the part must remain OEM, where K.8.5 only requires the footwells blocked off and K.8.1 allows alterations for aftermarket footholds.
Cite this page

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

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68 parts read · 19 permitted, 35 with conditions · 2026 rulebook

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