IHRA · Engine

Aftermarket valves, IHRA

IHRA answers this part for 24 of its classes. 5 of those answers permit the part outright and 8 permit it with stated conditions, leaving 11 that do not. 3 of the ones that do not are classes we read as open rather than as refusing it. 11 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 UIM. Which one applies to you is decided by whoever sanctions the race you enter.

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This is one body's answer, not the sport's. You are bound by whichever body sanctions the event you enter. If you race more than one series, build to the stricter answer. The differences are set out in the rulebook comparison.

Where it stands, class by class

24 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

Not permitted, not listed in the rules

Treat it as coming off. The class requires the craft to stay stock except where the rules allow otherwise, and this part is not on the list, so this is our reading rather than a rule we can quote at you.

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.

Not permitted, not listed in the rules 8 classes

On a closed list an unlisted modification is not permitted. · A.2.2, J.1

• Runabout Endurance
• Runabout Lites
• Runabout GP2
• Runabout GP3
• Drag, Sea-Doo vs Sea-Doo
• Ski GP3
• Runabout GP
• Drag, Turbo No Nitrous

Legal, with conditions 3 classes

Replacements must match OEM weight and dimensions.

• Ski GP2 · L.2.7
• Ski 1100 Modified · R.2.7
• Ski 1500 Modified · Q.2.7

Legal, with conditions 3 classes

Must meet OEM specifications. Oversized valves NOT allowed.

• Drag, Yamaha Pro Stock · DD.1
• Drag, Sea-Doo Pro Stock · DD.2
• Drag, Yamaha Spec · DD.3

Legal, with conditions 1 class

Four-stroke entries: TITANIUM COMPONENTS NOT ALLOWED unless originally equipped. · BB.2.9

• Runabout Limited

Legal, with conditions 1 class

Original activation method must be maintained. · K.2.7

• Ski GP

Legal 2 classes

Aftermarket valves are permitted, without the OEM specification and no-oversize rule of the Pro Stock and Yamaha Spec classes.

• Drag, Sea-Doo Spec · DD.4
• Drag, Super Stock · DD.5

Legal 1 class

Aftermarket valves, valve springs and valve spring retainers are allowed, with no further limit stated. · N.2.7

• Four-Stroke Ski Lites

Legal 1 class

P.1 applies N.2.7 of Four Stroke Ski Lites to four-stroke entries, which allows aftermarket valves, valve springs and valve spring retainers. · P.1, N.2.7

• Ski Limited

Legal 1 class

Four-stroke entries: Aftermarket permitted. · V.4.7

• Sport GP

No rule, this is an open class 2 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, 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

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Aftermarket valves: 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.