Not legal 3 classes
Only atmospheric 4-stroke 950 cc is listed.
- Runabout GP4 · 502.01
- Runabout Juniors GP4 · 302.01 · borrows another class
- Runabout Ladies GP4 · 302.01.01 · borrows another class
UIM · Forced induction
Aftermarket turbocharger or supercharger
Where allowed, the full circulating water-jacket rule is absolute.
Where it stands, class by class
24 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. 8 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.
Not legal 3 classes
Two-stroke atmospheric class.
- Ski Division GP3 · 501.02
- Ski Juniors GP3.2 · 302.01 · borrows another class
- Ski Juniors GP3.3 · 302.01 · borrows another class
Not legal 2 classes
Not a listed configuration; barred by the closed list.
- Ski Division GP4 · 501.01
- Ski Juniors GP4 · 302.01 · borrows another class
Not legal 1 class
Only atmospheric configurations listed.
- Runabout GP3 · 502.02
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 3 classes
Turbocharged four-stroke up to 1000 cc. Turbo housing AND exhaust manifold must be full circulating water type at all times when the engine is running. NO BOOST LIMIT IS PUBLISHED. · 501.04.01.01, 501.04.07
- Ski Division GP1
- Ski Ladies GP1 · borrows another class
- Ski Veterans GP1 · borrows another class
Legal, within limits 2 classes
BOTH turbocharging and supercharging on four-strokes, capped at 2000 cc. Water-jacketed housing and manifold required. NO BOOST LIMIT IS PUBLISHED. 502.04.01-01c, · 502.04-07
- Runabout GP1
- Runabout Veterans GP1 · borrows another class
Legal, within limits 1 class
SUPERCHARGED four-stroke up to 2000 cc. Turbocharging is NOT a general GP2 configuration - the sole turbo admission is the Belassi Burrasca, under an appendix that does not exist in the document. 502.03.01-01c, · 502.03.04-09
Legal, within limits 1 class
Turbocharged permitted, capped at 750 cc. The only named boost figure in the whole rulebook is 10-14 psi for the HSR-Benelli S4 (501.03.04-09), and that phrasing is ambiguous.
- Ski Division GP2 · 501.03
Aftermarket turbocharger or supercharger: 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.
Forced induction · four stroke · legal outright in 7 of 24