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Class Legality

UIM · Engine

Aftermarket valve springs, washers and retainers, UIM

UIM answers this part for 13 of its classes, and publishes no rule for it in 8 more. 2 of those answers permit the part outright and 0 permit it with stated conditions, leaving 11 that do not. 5 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. 6 are inherited from a parent class the rulebook points at.

This page is UIM only, and the bodies do not agree. The same part under IHRA and IJSBA. Which one applies to you is decided by whoever sanctions the race you enter.

Where it stands, class by class

21 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. 6 of them borrow another class’s rules and are marked below; for those, the link to the parent class is read from the categories table rather than stated in the rulebook. 8 publish no rule for this part and name no parent to borrow one from, and are grouped together at the end.

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
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.
No rule published for this class
Unanswerable here. This class publishes no rule for the part and names no parent class to borrow one from, which is an absence in the rulebook and not a permission.

Not permitted, not listed in the rules 3 classes

Not listed in this class. Illegal under the class's own stock clause.

Not permitted, not listed in the rules 2 classes

Valve spring, washer and retainer changes first appear at GP2, and Ski GP4 lists no valve train change, so the originals stay. · 501.01-02, 501.01.03

Not permitted, not listed in the rules 1 class

Only the valve cover may be modified or replaced, for cosmetic or weight-reduction purposes only. · 502.02.04-07

Legal 2 classes

Valve springs, valve washers and retainer washers may be modified or aftermarket. THE VALVES THEMSELVES MUST REMAIN ORIGINAL.

Aftermarket valve springs, washers and retainers: 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 UIM class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.

Engine · four stroke · legal in 2 of 13 answered

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BaddJet Class Legality