Not legal 3 classes
THE EXHAUST SYSTEM MUST REMAIN ENTIRELY OF ORIGIN as delivered by the manufacturer. · 501.02.03.03
- Ski Division GP3
- Ski Juniors GP3.2 · borrows another class
- Ski Juniors GP3.3 · borrows another class
UIM · Exhaust
Aftermarket expansion chamber / tuned pipe (2-stroke)
The sharpest class split in the UIM book, and it mirrors IJSBA almost exactly.
Ski GP3 is the UIM analogue of IJSBA Ski Lites: the 800cc two-stroke stand-up class, and no aftermarket pipe is legal in it. Say so on the product page rather than letting a buyer find out at scrutineering.
Where it stands, class by class
19 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. 5 of them publish no component rules of their own and are marked below; for those, the link to the parent class is read from the categories table rather than stated in the rulebook.
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.
Not legal 1 class
Two-stroke exhaust must remain entirely of origin. · 502.02.03-03
Governed by the parent 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
Legal, within limits 1 class
Manifold, head pipe, expansion chamber and connecting hose aftermarket; OEM waterbox mandatory; exit opening size and position maintained. · 502.03.03-07
Legal, within limits 1 class
Manifold, head pipe, expansion chamber, gaskets and the chamber-to-waterbox hose may be modified or aftermarket. The OEM WATERBOX must be used unmodified, the exit opening size and position must be maintained, and no tuned portion may protrude outside the hull. · 501.03.03.07
No rule, this is an open class 3 classes
No exhaust article beyond the turbo water-cooling rule. Free under the open-list reading.
- Ski Division GP1 · 501.04
- Ski Ladies GP1 · 314 · borrows another class
- Ski Veterans GP1 · 302.01.05 · borrows another class
No rule, this is an open class 2 classes
No exhaust article at all, so the same open-list reading applies here as in Ski · GP1.
- Runabout GP1
- Runabout Veterans GP1 · borrows another class
Aftermarket expansion chamber / tuned pipe (2-stroke): 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 · signed checks on parts the shop sells.
Exhaust · two stroke · legal outright in 2 of 19