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
IHRA answers this part for 29 of its classes. 3 of those answers permit the part outright and 20 permit it with stated conditions, leaving 6 that do not. 4 of the ones that do not are classes we read as open rather than as refusing it. 4 are inferred from how the class is written rather than quoted from a rule naming this part.
This page is IHRA only, and the bodies do not agree. The same part under IJSBA. Which one applies to you is decided by whoever sanctions the race you enter.
Where it stands, class by class
29 classes, grouped where the same rule gives the same answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules.
What each answer below means
- OEM part required
- This comes off. Only the part the manufacturer fitted is allowed here.
- 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.
- No rule, this is an open class
- Probably keep it. The class carries no stock clause at all, so anything unlisted appears to be open. The rulebook does not say so in terms, and this is our reading rather than a permission anybody wrote down.
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
Legal, with conditions 4 classes
Under the general maintenance allowance a cooling hose or clamp may be aftermarket; J.7 names no cooling fitting. · J.7
Legal, with conditions 2 classes
Fixed or automatic valves only, with outlets down and/or rearward.
- Ski GP · K.2.4
- Runabout GP · X.2.3
Legal, with conditions 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, with conditions 1 class
The OEM intercooler must be retained. · Y.2.4
Legal, with conditions 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, with conditions 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, with conditions 1 class
No modifications permitted to the cylinder head, cylinder, or crankcase. · O.2.4
Legal, with conditions 1 class
Under the general maintenance allowance a cooling hose or clamp may be aftermarket, and DD.1 keeps the jet pump stock except for its water fittings; no other fitting is named. · J.7, DD.1
Legal, with conditions 1 class
Model-dependent. A cooling hose may be replaced with an aftermarket one under the general maintenance allowance, and Kawasaki, Polaris and Yamaha craft may add cooling fittings. The Sea-Doo HX must keep its factory stock water routing with no additional bypass systems. · J.7, U.5.3, U.2.3
Legal, with conditions 1 class
Under the general maintenance allowance a cooling hose or clamp may be aftermarket, and DD.2 keeps the jet pump stock except for its water fittings; no other fitting is named. · J.7, DD.2
Legal, with conditions 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, with conditions 1 class
Model-dependent. Only water strainers and filters may be aftermarket on a four-stroke entry, with the rest of the cooling system and any intercooler fittings as originally equipped (P.1, N.2.4). A two-stroke entry may add aftermarket cooling lines and bypass fittings directed downward or rearward under O.2.4, plus the additional cooling fittings P.2.6 names, with no change to the cylinder or crankcase. · N.2.4, O.2.4, P.2.6
Legal, with conditions 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, with conditions 1 class
Aftermarket cooling lines and bypass systems may be used, but every cooling valve must be fixed or automatic, with no manual control of water flow. · T.2.4
Legal, with conditions 1 class
Aftermarket cooling systems are permitted; four-strokes must point bypass fittings downward or rearward and use only fixed or automatic valves, and V.2.4 holds two-strokes to flow and operation regulations it does not spell out. · V.2.4, V.4.3
Legal, with conditions 1 class
Under the general maintenance allowance a cooling hose or clamp may be aftermarket (J.7). Read as what DD.7's "Watercooled Only" presupposes, the water lines and fittings that cool the turbo and its header are admitted as well, and no other added cooling fitting is listed. · J.7, DD.7
Legal 2 classes
The engine cooling system may be modified and extra cooling lines or bypass fittings added, provided nothing creates a hazard and outlets are directed away from other competitors.
- Ski 1100 Modified · R.2.4
- Ski 1500 Modified · Q.2.4
Legal 1 class
The cooling system may be modified with aftermarket cooling lines and water bypass systems, provided no hazard is created for other riders. · S.2.4
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 · checks on parts the shop sells · how this site reads a rulebook.
Cooling · two and four stroke · legal in 23 of 29 answered, 20 with conditions