Rules are rewritten most seasons, and the bodies running these classes do
not agree with each other. So every check names the body it was made
against and, where it has one, the rulebook year.
New to this? Start here walks the whole path
into a first race, from watching one to reading the result, with each
step citing the rule behind it. For the gear side,
what you actually
need for a first race (on the shop) 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.
Which body applies to you is decided by the event, not by the
part. Whoever sanctions the race you enter sets the rulebook you
are judged against, so ask the club running it before you read any answer
below as yours. The directory of organisations and affiliates
says who runs racing where, and which class is for me walks it
from the machine you own.
The class rulebook, read against one product, with its section where there is one.
13 checks, listed further down this page.
Two different things are on this page.
First the checks: 13 of them, each against one part the shop sells.
Then the rulebook reference:
4170 answers read out of the published rulebooks, one for each part
in each class it applies to, a class that borrows another's rules
answered through it. The second is useful and it is not
the first, and nothing on this site lets a reading borrow a check's badge.
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.
Not legalSki Lites · IJSBA · 2024 rulebook · SKL.3.6
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.
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.
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.
Under J.18.2 an impeller may be modified or replaced with an aftermarket one, "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.
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.
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.
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.
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.
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. This verdict covers the mat kit alone. The archive's IHRA entry for footholds, foot straps and tray mats reads legal with conditions, because J.14 does not name footholds or foot straps and they stay not permitted in Ski Lites.
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 IJSBA checks here. The same rule separately allows custom painting and the polishing or plating of exterior metal above the bond flange. The answer here is for the mat on its own. The archive groups mats with footholds and padding under IJSBA and reads that entry as legal with conditions, since the rules add that any footwells must be blocked off during competition, with no indentation into their sides.
Read out of the published rulebooks. Every answer names its rulebook year
and section so you can go and read the rule rather than take a badge on
trust.
1
Does the class publish component rules of its own?
Some classes only set who may enter, and race under another class’s technical rules.
The rule’s own answer: “Legal”, “Legal, with conditions”, “OEM part required” or “Not legal”.
Quoted from the class document, with its section beside it.
6
Does the class’s own text carry another class’s rules in, and do they answer it?
The class records name IJSBA Vintage Ski Limited, Runabout Limited and Runabout Superstock; UIM Ski Division GP2 and Runabout GP2; IJSBA Sport Spec does it too, for one Kawasaki model. The UIM GP2 clause carries in only what GP3 permits, never a GP3 refusal. The readings do not always take this route: a few silent parts in these classes end at another label without saying why.
Our reading of the closed list, not a rule anyone wrote about this part. Drawn dashed.
11
“No rule, this is an open class”
Our reading too: no rule names this part, so the open default is applied. Drawn dashed.
12
“The rules do not say”
Neither answer is safe to assume; ask the club running the race.
13
“Not applicable to this craft”
Left off the class and part pages.
14
“No rule published for this class”
Shown on the part pages: a gap in the rulebook, never a permission.
Every answer in the rulebook reference ends at one of these labels. The two dashed endings are our readings of a class’s default, applied to a part no rule names.
How we know: the class records (whether a class has rules of its own, the class it races under, any other class its text carries in, closed list or set of limits) and the part readings, all taken from the IJSBA, UIM and IHRA rulebooks; the labels are the ones the class and part pages print.
IHRA, International Hot Rod Association, Pro Watercraft Racing
2026 rulebook · one 95-page PDF, version V.20260603, sections A to EE ·
29 classes ·
81 part types · 2065 answers
Homologation at 300 units, sound measured at
22.86 m. Region: 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 ·
61 part types · 1093 answers
Homologation at 500 units, sound measured at
22.86 m. Region: 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.
If you race in two series, build to whichever answer is stricter.
3 of the 3 possible pairs are compared,
and the comparison page names any pair that 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.