Not legal 1 class
Exhaust must remain stock as supplied by the manufacturer. Only a stinger insert and cooling lines are allowed. · SKL.3.6
IJSBA · Exhaust
Aftermarket exhaust manifold / head pipe, IJSBA
Usually sold with the chamber but governed by the same class rules.
This page is IJSBA only, and the bodies do not agree. The same part under IHRA. Which one applies to you is decided by whoever sanctions the race you enter.
Where it stands, class by class
20 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.
What each answer below means
- Not legal
- This comes off. The rules refuse it in this class.
- OEM part required
- This comes off. Only the part the manufacturer fitted is allowed here.
- 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.
- The rules do not say
- Unanswered. The rules do not settle this, so ask the club before you rely on it.
- 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.
OEM part required 1 class
RAS.4.5 keeps a two-stroke exhaust system stock as supplied, with only a stinger insert, and RAS.3.8 lists no aftermarket manifold or head pipe for a four-stroke, allowing a manifold previously drilled or tapped once the holes are filled or capped, and flange removal. · RAS.1.1, RAS.3.8, RAS.4.5
Not permitted, not listed in the rules 1 class
No exhaust section exists in FSSK.
- Fixed Steering Ski Stock · FSSK
Not permitted, not listed in the rules 1 class
No exhaust section appears in RRL at all.
- Runabout Rec Lites · RRL
Not permitted, not listed in the rules 1 class
No exhaust section exists in SSK.
- Ski Stock · SSK
Not permitted, not listed in the rules 1 class
FSKL.3.6 lists no aftermarket manifold or head pipe: a manifold previously drilled or tapped may be used once the holes are filled or capped, aftermarket hose or piping may run only from the water box to the exhaust outlet pipe, and the water box and manifold outlet may not be modified. · FSKL.1.1, FSKL.3.6
Not permitted, not listed in the rules 1 class
SKM.3.9 and SKM.4.9 list no aftermarket manifold or head pipe and allow only an exhaust manifold previously drilled or tapped, once its holes are filled or capped. · SKM.1.1, SKM.3.9, SKM.4.9
The rules do not say 1 class
Four-stroke exhaust is genuinely not addressed in the Runabout Limited rules, so the Stock class answer reaches it through the inheritance rule. · RAL.1.1
Legal, with conditions 1 class
Manifold, head pipe and expansion chamber allowed, but exhaust may NOT be relocated and the exit opening may not exceed 2 inches. · VSKL.3.7
Legal, with conditions 1 class
RNA.4.7 lets the exhaust manifold, head pipe, expansion chamber, gaskets and the hose to the OEM waterbox be modified, altered or aftermarket, keeping the exhaust gas location and the original exit opening size, with the OEM waterbox unmodified and no tuned portion outside the hull. · RNA.4.7
Legal, with conditions 1 class
Model-specific.
- Sport Spec · section headings, no numbered rules
Legal 3 classes
Manifold, head pipe, expansion chamber, waterbox and muffler modified or aftermarket.
- Vintage SC · VSC.3.7
- Vintage X2 · VX2.3.7
- Vintage Ski · VSK.3.7
Legal 3 classes
The exhaust system may be modified or aftermarket on every engine, the two-stroke manifold and head pipe and the four-stroke manifold and connecting pipes included.
- Freestyle · FREST.3.7, FREST.7.8
- Ski Grand Prix · SKGP.3.7, SKGP.6.8, SKGP.7.8
- Sport GP · SPGP.4.8, SPGP.5.9
Legal 2 classes
Manifold, connecting pipes, hoses and mufflers modified or aftermarket, with no tuned portion outside the hull.
- Ski Superstock · SKSS.3.8
- Runabout Open / GP · ROP.4.8
Legal 1 class
The exhaust system may be aftermarket providing a hazard is not created. · RSS.3.13
Aftermarket exhaust manifold / head pipe: 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 IJSBA class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.
Exhaust · two and four stroke · legal in 12 of 20 answered, 3 with conditions