Not permitted, not listed in the rules 8 classes
On a closed list an unlisted modification is not permitted. · A.2.2, J.1
IHRA · Engine
Base gasket thickness change
IHRA answers this part for 14 of its classes. 2 of those answers are permissions, with or without limits attached, and 12 are not. 12 are inferred from how the class is written rather than quoted from a rule naming this part.
Where it stands, class by class
14 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.
Legal, within limits 1 class
Limits: max thickness 0.8 mm, sub 780cc min thickness 0.5 mm. · O.2.6
Legal, within limits 1 class
Limits: two stroke max thickness 0.8 mm. · M.2.1
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
Base gasket thickness change: 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.
Engine · two stroke · legal outright in 2 of 14