Ducting between flame arrester and throttle body / compressor, UIM

Legal in every class that addresses it - the cheapest legal induction change in the closed-list classes.

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. 8 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

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.
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.

Legal, with conditions 1 class

Four-stroke: ducting from the flame arrester to the throttle body or intake manifold inlet is free to modify or replace. Two-stroke: Runabout GP3 omits the ducting sentence Ski GP3 prints, so two-stroke ducting stays original. · 502.02.06-02, 502.02.05-01

Runabout GP3

Legal 5 classes

The ducting between the flame arrester and the throttle body or intake manifold inlet may be modified or aftermarket.

Runabout GP4 · 502.01.04-02
Ski Division GP4 · 501.01.04.02
Runabout Juniors GP4 · 502.01.04-02 · borrows another class
Runabout Ladies GP4 · 502.01.04-02 · borrows another class
Ski Juniors GP4 · 501.01.04.02 · borrows another class

Legal 3 classes

Ducting, support and adapter between flame arrester and carburettor. · 501.02.04.01

Ski Division GP3
Ski Juniors GP3.2 · borrows another class
Ski Juniors GP3.3 · borrows another class

Legal 1 class

Including ducting to the COMPRESSOR on supercharged craft. · 502.03.06-02

Runabout GP2

Legal 1 class

Two-stroke: the GP3 allowance for the ducting, support and adapter between flame arrester and carburettor carries over. Four-stroke: ducting from the flame arrester to the throttle body, intake manifold inlet or compressor may be modified or aftermarket. · 501.03-02, 501.02.04.01, 501.03.06.02

Ski Division GP2

No rule, this is an open class 5 classes

No article covering this part. Free under the open-list reading of GP1.

Ski Division GP1 · 501.04
Runabout GP1 · 502.04
Runabout Veterans GP1 · 302.01.05 · borrows another class
Ski Ladies GP1 · 314 · borrows another class
Ski Veterans GP1 · 302.01.05 · borrows another class

No rule published for this class 8 classes

No component rules are published for this class and no single parent class is named, so this part cannot be answered for it. That is an absence in the rulebook, not a permission.

Endurance · 317.03
Freestyle Amateur · 312
Freestyle Free · 312
Jet Raid · 317.01
Offshore · 317.02
Parallel Slalom · 313
Ski Future Electric (SFE) · 302.01
UIM Hydro-Fly · 900

Ducting between flame arrester and throttle body / compressor: 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.

Fuel · two and four stroke · legal in 11 of 16 answered, 1 with conditions