OEM part required 1 class
Must remain OEM. Aftermarket water strainers or filters permitted. Intercooler assembly and fittings OEM. No additional fittings. Electronic valve or water injection prohibited unless OEM. · AA.2.4
IHRA · Cooling
Aftermarket cooling lines and fittings
IHRA answers this part for 29 of its classes. 14 of those answers are permissions, with or without limits attached, and 15 are not. 13 are inferred from how the class is written rather than quoted from a rule naming this part.
Where it stands, class by class
29 classes, grouped by the answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules.
Not permitted, not listed in the rules Our reading, not a rule we can quote at you. This class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list.
No rule, this is an open class Our reading, not a rule we can quote at you. This class carries no stock clause at all, so anything unlisted appears to be open. The rulebook does not say so in terms.
OEM part required 1 class
Must remain OEM, with only water strainers and filters aftermarket and the intercooler assembly and its fittings OEM. · N.2.4
Not permitted, not listed in the rules 9 classes
On a closed list an unlisted modification is not permitted. · A.2.2, J.1
Legal, within limits 1 class
Model-dependent. On the Kawasaki Ultra 300 and Ultra 310 the oil cooler kit, fittings and hoses may be aftermarket (W.2.5). On Sea-Doo craft closed-loop cooling systems must remain in place (W.2.5). On Sea-Doo and Yamaha craft one additional through-hull cooling supply line and pump fitting is allowed, Yamaha may use the engine block anode fitting as a cooling source, and existing fittings stay at OEM thread diameter. · W.3.7
Legal, within limits 1 class
The OEM intercooler must be retained. · Y.2.4
Legal, within limits 1 class
On two-stroke entries no fitting may be added to the cylinder head, cylinder or crankcase, only fixed or automatic valves are allowed, and electronic valves and water injection are prohibited unless OEM. · Z.3.2
Legal, within limits 1 class
No new fittings on the engine block. Existing unused fittings may become water supply lines at unchanged thread diameter, and electronic valves and water injection are prohibited unless OEM. · L.2.4
Legal, within limits 1 class
No modifications permitted to the cylinder head, cylinder, or crankcase. · O.2.4
Legal, within limits 1 class
2-stroke: max 2 cylinder-head cooling outlets, no larger than 1/8 inch NPT. No additional fittings. Head must remain stock OEM with no modifications. 4-stroke (M.3.2): waterlines and fittings aftermarket only at OEM size. · M.3.1
Legal, within limits 1 class
OEM intercooler assemblies must remain in stock class. Volume changes to OEM water supply fittings prohibited. No fittings may be added to the cylinder head, cylinder, or crankcase. · BB.2.4
Legal, within limits 1 class
Fixed or automatic valves only, with outlets down and/or rearward. · K.2.4
Legal 6 classes
Aftermarket permitted.
- Ski 1100 Modified · R.2.4
- Ski 1500 Modified · Q.2.4
- X2 Vintage · T.2.4
- Ski Vintage · S.2.4
- Sport GP · V.2.4
- Runabout GP · X.2.3
No rule, this is an open class 3 classes
The class states only what it bans and calls itself run what you brung, against a section DD preamble that says anything unlisted is illegal.
- Drag, 2 Stroke Unlimited · DD.12
- Drag, Stand Up Unlimited · DD.10
- Drag, Unlimited · DD.6
No rule, this is an open class 1 class
No restriction in section CC, and CC.1 permits any modification it does not restrict.
- Freestyle · CC
Aftermarket cooling lines and fittings: if the rule your class applies reads differently to you, or the rulebook has changed since this was read, ask. We answer with the section we read it from, or that we have not read it. Ask a rules question.
Every IHRA class · where the rulebooks differ · signed checks on parts the shop sells.
Cooling · two and four stroke · legal outright in 14 of 29