BaddJet Archive Home

Class Legality

IHRA · ski

Four-Stroke Ski Lites

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

  • 1Not legal
  • 11OEM part required
  • 27Not permitted, not listed in the rules
  • 20Legal, with conditions
  • 9Legal

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
Exclusively the Yamaha SuperJet four-stroke, 2021 or later.
Displacement limit
1100cc (N.1). N.2.1 permits the engine to be bored and does not repeat the figure. N.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 (1)

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.

  • N.2.6 carries the same self-contradictory head gasket rule as L.2.6 and O.2.6, with the same wrong unit conversion. No numeric gasket tolerance is publishable for this class.

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-substitution rule. The hull article, N.5, covers only ventilation and the hood.
  • No forced induction article.

What the rules say (68 parts)

9 permitted outright, 20 permitted with stated conditions, 1 refused by a rule we can quote, 11 held to the original part by a rule we can quote and 27 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

N.2.5 allows no modification to the water box, which stays as supplied while aftermarket piping runs from it to the outlet pipe. N.2.5

OEM part required1 part

The intake manifold, with its screens and spark suppressors, must remain stock. N.3.1

OEM part required1 part

The original ECU must stay and may only be reprogrammed, keeping the same input and output count, with no sensor added, so an aftermarket or standalone box is not legal here. N.4.1

OEM part required1 part

N.2.4 keeps the intercooler assembly and its fittings as originally equipped, with the rest of the cooling system. N.2.4

OEM part required1 part

Must remain OEM, with only water strainers and filters aftermarket and the intercooler assembly and its fittings OEM. N.2.4

OEM part required1 part

A ski hull may be repaired, or reinforced against course obstacles, but only within 2 mm (0.08 in) of its original configuration, and no other hull work is listed. J.1, J.13

Not permitted, not listed in the rules25 parts

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

Not permitted, not listed in the rules1 part

N.2.5 lists no aftermarket manifold or head pipe: aftermarket piping may route exhaust only from the water box to the outlet pipe, the water box and manifold outlet may not be modified, and holes previously drilled or tapped in the manifold must be filled or capped. A.2.2, J.1, N.2.5

Not permitted, not listed in the rules1 part

N.2.5 allows aftermarket piping from the water box to the exhaust outlet pipe and bars changes to the water box and manifold outlet; the outlet itself is not listed, and under J.1 and A.2.2 an unlisted modification is not permitted. N.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. N.3.1

Legal, with conditions1 part

The ducting between the flame arrester and the throttle body may be modified or aftermarket, or only as far as the airflow sensor where one is fitted, and nothing downstream of the sensor may change. No cold air system is named, so the allowance stops at that ducting. N.3.1

Legal, with conditions1 part

Reprogramming the original unit is the permitted route, keeping the same input and output count, with no sensor added. N.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

Boring is allowed provided the piston keeps its compression ratio, dome profile, skirt length and material type, and chambers are bead blasted only with no steel wool or Scotch-Brite. N.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

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

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. N.5.1

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

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

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, N, 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 Four-Stroke Ski Lites 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 Four-Stroke Ski Lites 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, Four Stroke Ski Lites: the cell had been graded from a note about the piping.
Cite this page

“Four-Stroke Ski Lites, IHRA class rules”, BaddJet archive, https://baddjetarchive.com/legality/ihra/four-stroke-ski-lites/

Add the date you read it.

68 parts read · 9 permitted, 20 with conditions · 2026 rulebook

Start
BaddJet Class Legality