The rules do not say 1 class
The SKM document gives no chamfering allowance, unlike the other stock classes.
- Ski Modified · SKM
IJSBA · Engine
Port chamfering service (within the appendix limit), IJSBA
Legal in most closed-list classes at exactly 1.00mm / 30 degrees maximum.
This page is IJSBA only, and the bodies do not agree. The same part under UIM. 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
- 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.
Legal, with conditions 8 classes
Permitted, subject to the limits IJSBA applies to every class, namely the sound ceiling, the hull repair tolerance, and the intake grate and sponson dimensions.
- Fixed Steering Ski Stock · FSSK
- Runabout Rec Lites · RRL
- Four Stroke Ski Lites · FSKL
- Runabout Naturally Aspirated · RNA
- Runabout Stock · RAS
- Ski Lites · SKL
- Sport Spec · section headings, no numbered rules
- Runabout Limited · RAL
Legal, with conditions 1 class
Max 1.00mm (0.04 in) at max 30 degrees.
- Ski Stock · SSK
Legal, with conditions 1 class
The only Vintage class with an explicit numeric chamfer limit. · VSKL.3.1
Legal 3 classes
The cylinder may be modified or aftermarket and port diameters and shapes may be changed, so a chamfer within the appendix limit is covered.
- Vintage SC · VSC.3.2, VSC.3.3
- Vintage X2 · VX2.3.2, VX2.3.3
- Vintage Ski · VSK.3.2, VSK.3.3
Legal 2 classes
Intake and exhaust ports may be modified in diameter and shape, so a chamfer within the appendix limit is covered.
- Runabout Superstock · RSS.3.3
- Runabout Open / GP · ROP.4.2
Legal 2 classes
Two-stroke cylinders may be modified or aftermarket and four-stroke ports may be changed in diameter and shape, so a chamfer within the appendix limit is covered.
- Freestyle · FREST.3.3, FREST.7.2
- Ski Grand Prix · SKGP.3.3, SKGP.6.2, SKGP.7.2
Legal 1 class
Superseded by the full porting allowance.
- Ski Superstock · SKSS
Legal 1 class
Four-stroke ports may be changed in diameter and shape, but any modification to a two-stroke cylinder, a chamfer included, needs written IJSBA approval. · SPGP.4.2, SPGP.5.5
Port chamfering service (within the appendix limit): 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.
Engine · two and four stroke · legal in 19 of 20 answered, 10 with conditions