Rules are rewritten most seasons, and the bodies running these classes do
not agree with each other. So every check names a body, a rulebook year, a
person and a date, or it is not a check.
Entering a first event? What you actually
need for a first race checks three published beginner guides against
the same rulebook readings this section is built on, including the
freestyle carve-outs on the helmet, the lanyard and back protection.
Two different things are on this page, in order of proof.
First the checks: 16 of them, each against one part the shop sells,
each signed by the person who made it. Then the rulebook reference:
4023 answers read out of the published rulebooks, none of them
checked by anybody against a machine. The second is useful and it is not
the first, and nothing on this site lets a reading borrow a check's badge.
Checked, and signed (16)
Each of these is one part the shop sells, against one class, checked by a named
person on a named date. Rules are reissued most seasons: a check against
a 2024 rulebook is an answer about 2024.
The rule is read and the part is not. M.6.2.1.2 permits a manufactured, designed and sold wet pipe on a SuperJet running the 701 cylinder, and forbids converting a dry pipe into one, so everything depends on which kind of pipe this is. Factory Pipe sells its Kawasaki pipes as separate wet and dry products and names them so; it names no SuperJet product a wet pipe, and it does name one "SuperJet Dry". The 701 kit's own parts list includes a dry manifold, and its instructions treat water injection as an optional separate system with its own spray bar and its own instructions. The waterlines in that kit are the engine cooling circuit, which is a different thing from water in the exhaust. Until Factory Pipe confirms which model this is and whether it is sold as a wet pipe, this part has no answer in this class. Four further conditions would apply to the rest of the machine even if it did: OEM CDI and CDI box, no altered ignition timing, OEM head and base gasket thickness, and an OEM cylinder bored no more than 1mm. Fitting the 760 cylinder removes the allowance entirely, because that option requires the exhaust to remain stock.
Nobody has checked this part against the IHRA Ski GP3
rulebook, so its status there is unknown rather than fine.
O.2.5 requires the exhaust system to remain stock. It permits an insert to reduce the stinger portion's diameter and cooling lines added to that insert, and states that no performance-enhancing modifications are allowed. A complete aftermarket pipe is not among the permitted changes. IHRA also applies A.2.2, under which the absence of a permitting rule does not imply permission, so there is no reading on which this clears.
SKL.3.6 requires the exhaust system to remain stock as supplied by the manufacturer. The only exhaust changes it permits are an insert to reduce the inside diameter of the stinger portion, cooling lines added to that insert, or a cooling line on the stinger where no insert is used. A complete aftermarket pipe is none of those. This is a direct prohibition rather than an omission.
J.14 permits padding and mat kits with no limit attached. It sits in the universal section rather than the Ski Lites chapter, so it holds across every class in the IHRA rulebook rather than only this one, which is why fitting a mat cannot cost you a class here.
SKL.2.10 permits padding and mat kits outright. No dimensional limit, no material restriction and no approval requirement is attached to them, which makes this the only unconditional yes among the parts stocked here. The same rule separately allows custom painting and the polishing or plating of exterior metal above the bond flange.
The ride plate rule is universal across IHRA classes and names the Ski class directly, so it reaches GP3 unchanged: an aftermarket or modified plate is permitted, any extension may not exceed the original plate's width, and the plate may not extend more than 3.94 inches (100mm). Watch the interaction with M.6.2.1.1, which separately allows a SuperJet hull extension of up to 100mm beyond the original planing surface, because the two limits are measured from different places and a rider running both should check them together.
J.18.1 permits an aftermarket or modified ride plate. Extensions added to it must not exceed the width of the original plate, and for the Ski class an aftermarket ride plate must not extend more than 3.94 inches (100mm). All components must be free of hazardous edges, a condition IJSBA does not state in those words. Check the plate against a tape and against the original before you run it.
IJSBA calls this component the pump cover plate, and SKL.2.5 permits a modified or aftermarket one. Three conditions apply and all are dimensional: a rear extension must not exceed the width of the original equipment plate, the plate must not extend more than 100.00mm (3.94 in.) beyond the end of the original plate, and fins, rudders, skegs or other appendages that may create a hazard are not allowed. The sides of any extension must connect to the radiused portion of the plate. Do not confuse this with a fixed trim tab or a hull extension, which are different parts governed by SKL.2.7 and may not be used in Ski Lites at all, and note that SKL.2.6 separately restricts trim plates to replicas matching stock handling. Measure the plate before racing it.
The same wrinkle applies here: J.18.2 permits an aftermarket impeller but attaches its original-diameter requirement to "Stock class", a phrase this rulebook otherwise reserves for its drag racing categories. Treat the diameter as fixed until an inspector says otherwise. Ski GP3 does give the Kawasaki pump work the Yamaha does not have: M.6.1.3 permits boring the pump nozzle and adding pump stuffers, and M.6.1.5 permits boring the OEM nozzle on 800 models. This part is also out of production, which is a separate problem from legality.
J.18.2 permits impellers to be modified or replaced with aftermarket parts, "though the original diameter must be maintained in Stock class". IHRA runs no class named Stock, so whether that restriction binds Ski Lites is unstated. Treat it as binding, confirm the diameter with the technical inspector, and note separately that this part is no longer manufactured.
SKL.6.1 permits a modified or aftermarket impeller provided the original diameter is maintained, so confirm the diameter of the specific impeller against the pump it goes into. The rule also allows replacement wear rings within OEM internal diameter specifications and requires the visibility spout to be removed or plugged.
J.18.2 allows an aftermarket impeller but ties the original-diameter requirement to "Stock class", and IHRA uses that phrase for its drag racing classes rather than for any Ski class. Whether it reaches Ski GP3 is therefore genuinely unclear. Assume the diameter must be kept, get the answer from the event's technical inspector before you commit money to it, and note that GP3 separately permits the SuperJet nozzle to be modified for angle adjustment under M.6.2.1.3.
J.18.2 permits impellers to be modified or replaced with aftermarket parts, "though the original diameter must be maintained in Stock class". IHRA has no class actually named Stock, so whether that diameter restriction binds Ski Lites is not stated. Treat it as binding and confirm the diameter of the specific impeller with the event's technical inspector, because under A.2.2 the absence of a permitting rule does not imply permission.
SKL.6.1 permits a modified or aftermarket impeller provided the original diameter is maintained. The condition is on the part you actually fit, so confirm the diameter of the specific impeller against the pump it goes into. The same rule allows replacement wear rings within OEM internal diameter specifications and requires the visibility spout to be removed or plugged.
Read out of the published rulebooks and not verified by a racer. Every
answer names its rulebook year and section so you can go and read the rule
rather than take a badge on trust.
IHRA, International Hot Rod Association, Pro Watercraft Racing
2026 rulebook · one 95-page PDF, version V.20260603, sections A to EE ·
29 classes ·
79 part types · 2291 answers
Homologation at 300 units, sound measured at
22.86 m, Not stated in the rulebook. A.2.4 fixes choice of law and venue exclusively in Ohio, and B.7 requires an eligible model to be sold through a distribution network reaching the global market. No territory is named anywhere in the document..
IJSBA, International Jet Sports Boating Association
2025 rulebook · 25 separate PDFs, rule years 2021-2025 ·
20 classes ·
59 part types · 1180 answers
Homologation at 500 units, sound measured at
22.86 m, Primarily North America and the IJSBA affiliate network.
Its class documents carry different rule years, so two of its classes can disagree because they were written seasons apart.
The lists above are organised by class, which is how a rulebook is
written and not how anybody asks the question. If you already know the
part and want to know which classes will take it,
legality by part puts every part the
rulebooks address in one place, with how many classes answer each one
and how many of those answers are our reading rather than a quoted rule.
Where the rulebooks disagree
A machine legal under one body is not automatically legal under another,
and where two of them govern you, you are held to the stricter answer.
Two comparisons are written, IJSBA against UIM and IJSBA against IHRA.
The page names the third, which is not.
The differences that change what you would buy, from homologation
thresholds to camshafts to helmet standards, are set out in
the rulebook comparison.
Confirm before a sanctioned event regardless of what any website tells you,
including this one. Homologation thresholds differ by body, so a part
clearing one bar can fail the other.