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What is actually legal in IJSBA Ski Lites

Ski Lites is a closed list, so the question is not what the rulebook bans but what it names. Three answers catch people out at tech inspection, and one of them makes the most wanted part on this site illegal in the class.

What this rests on

Basis
From a rulebook
Source
IJSBA 2024 Ski Lites class document, rule prefix SKL, read for this site's class and part pages and read again on 11 September 2026.
Difficulty
Bolt-on

The list is closed, and that is the whole rule

Ski Lites works by naming what may be changed. A component the class document never mentions is not therefore free; it is not permitted. That single principle decides more questions than every specific article in the document put together, and it is why a part can bolt straight on, work perfectly, and still put you out at inspection. Of the fifty nine component answers this site holds for the class, seven are refusals that rest on nothing but the rulebook's silence.

Closed list

Ski Lites (SKL) names the changes allowed; anything it never names stays as the manufacturer supplied it.

  • A change the document lists

    goes through

    • Legal
    • Legal, with conditions where the list sets a limit

  • A change it never lists

    stops

    • Not permitted, not listed in the rules

Set of limits

The class states what may not change, or how far it may go, and leaves the rest open.

  • A change inside every stated limit

    goes through

    • Legal, with conditions where a rule names it
    • No rule, this is an open class where none does

  • A change past a stated limit

    stops

    • Not legal

Other classes in the same rulebook written this way

  • Stated: no IJSBA class; even its Modified, Grand Prix, Open and Freestyle documents allow only the changes they name, though their lists are broad (SKGP.1.1, ROP.1.1, SPGP.1.1, FREST.1.1, SKM.1.1).

Ski Lites is written as a closed list, so the first thing to ask of any change is whether the document lists it.

How we know: the IJSBA 2024 Ski Lites document (SKL), as the class records hold it: the rule type each record carries, and the closed-list clause SKL.1.1. The endings are the answers the class pages print.

The exhaust stays exactly as the manufacturer supplied it

SKL.3.6 requires the system to remain stock. The only thing you may add is an insert in the stinger portion to reduce its inside diameter, plus cooling lines run to that insert or the stinger. Manifold, head pipe, expansion chamber, waterbox and any through-hull relocation are all out. This is the rule people most often discover late, because the part that breaks it is the first one most riders buy.

Exhaust sections 1 to 3, from the engine A box at the left stands for the engine. Bolted to it, a short tapering casting numbered 1 leads into a narrow straight tube numbered 2, with a small arrow inside it pointing right. The tube then flares into a wide body that widens, runs straight and begins to narrow again, numbered 3. A dashed line at the right edge marks where the drawing continues in the next panel. engine 1 manifold 2 head pipe 3 expansion chamber Exhaust sections 4 to 6, out through the hull Carrying on from a dashed line at the left, the narrowing end of the wide body becomes a thin tube numbered 4, and a dashed water line rises into it from below. A shorter, slimmer hose joins it to a closed box numbered 5. From the far side of the box a tube runs right to an open end, an arrow carries on past it to the outside, and the number 6 sits under it. 4 stinger hose 5 waterbox out 6 outlet through the hull cooling water

In order from the engine: manifold, then head pipe, expansion chamber, stinger, a hose, waterbox, and the outlet through the hull.

Gas from the engine meets these sections one after another. A class document can open some of them and hold the rest to the original part, so each section carries its own name in the rules.

How we know: the order is the one IHRA's rule P.2.1 lists and US patent 6,113,446 describes in paragraphs 28 to 30; the stinger and its cooling line are IJSBA's Ski Lites rule SKL.3.6.

Not to scale.

Reed petals yes, reed cage no

SKL.4.3 splits a component most catalogues sell as one item. Modified or aftermarket reed valve petals are allowed. Any modification to the reed cage assembly is prohibited. If you are shopping from a listing that says reed kit, you need to know which half of that kit you are buying, because one half is legal here and the other ends your day.

Trim tabs are out, but the brackets may stay on the hull

SKL.2.7 prohibits hull extensions and trim tabs in this class while allowing existing mounting brackets to remain. That matters if you run the same ski in more than one class: you do not have to strip the mounting hardware back off to be legal here, only the tabs themselves. Rider-controlled and automatic systems are refused outright.

What the class does leave you

More than its reputation suggests. An aftermarket impeller at the OEM diameter, a wear ring, a pump cover plate within the published extension limit, up to two sponsons within a maximum drop, an intake grate to the stated pattern, an aftermarket or modified ignition box keeping the original inputs and outputs, pistons within a weight tolerance and retaining original port timing, and an aftermarket cylinder sleeve cut to OEM port specifications. The handlepole may be aftermarket. So may the steering, the handlebars and the flame arrester.

The part we sell that you may not run here

We stock a Factory Pipe for the SuperJet. It is prohibited in Ski Lites, it is recorded as prohibited in a legality check against both this body and IHRA, and no reading of SKL.3.6 rescues it. Of the other parts on this site checked against the class, the mat is clear, and the ride plate and both impellers are legal within stated limits. That is the honest shape of the catalogue against this class, and it is shorter than we would like it to be.

Four things the class document does not settle

Its sponson figures are internally inconsistent, giving a per-sponson length that does not reconcile with a stated total under a two-sponson maximum. Its intake grate limit differs from the figure every other class in the same rulebook uses. One driveline citation looks like a transcription artefact rather than a rule. And the eligible craft are named without model years, so the class is defined by machine rather than by date. None of that is our reading being cautious; it is what the document does and does not say.

Parts this is about

  • Factory Pipe exhaust, Yamaha SuperJet 701

    Factory Pipe · FP-SJ701

    Data not confirmed

    IHRA Ski GP3 (status unknown) · IHRA Ski Lites (not legal) · IJSBA Ski Lites (not legal)

  • Solas impeller, Yamaha SuperJet 701

    Solas · SOL-SJ701

    Data not confirmed

    IHRA Ski GP3 (legal with conditions) · IHRA Ski Lites (legal with conditions) · IJSBA Ski Lites (legal with conditions)

    Jet pump, impeller marked

  • Skat-Trak impeller, Kawasaki SX-R 800

    Skat-Trak · SKAT-SXR800

    Data not confirmed

    IHRA Ski GP3 (legal with conditions) · IHRA Ski Lites (legal with conditions) · IJSBA Ski Lites (legal with conditions)

    Jet pump, impeller marked

  • RIVA Racing ride plate, Yamaha SuperJet

    RIVA Racing · RIVA-SJ-RP

    Data not confirmed

    IHRA Ski GP3 (legal with conditions) · IHRA Ski Lites (legal with conditions) · IJSBA Ski Lites (legal with conditions)

    Jet pump, ride plate marked

  • Hydro-Turf traction mat, Yamaha SuperJet

    Hydro-Turf · HT-SJ-MAT

    Data not confirmed

    IHRA Ski Lites (legal) · IJSBA Ski Lites (legal)

Symptoms this addresses: Told at tech that my pipe is not legal · Not sure whether reeds are allowed in a stock class · Failed inspection over trim tabs · Want to know what I am actually allowed to change. All symptoms.

Cite this page

“What is actually legal in IJSBA Ski Lites”, BaddJet archive, https://baddjetarchive.com/tech/class-rules/what-is-legal-in-ski-lites/

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Class rules · Bolt-on

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