IJSBA · Engine
IJSBA answers this part for 20 of its classes. 7 of those answers permit the part outright and 6 permit it with stated conditions, leaving 7 that do not.
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.
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.
OEM part required 5 classes
The crankshaft must remain stock; replacement bearings or bearing shells are allowed if they keep their original type and dimensions.
OEM part required 1 class
Crankshaft must remain stock. · SSK.3.2
OEM part required 1 class
Crankshaft must remain stock in both displacement categories.
Legal, with conditions 1 class
Rebuild only. 110mm rods and 60mm stroke ONLY. +/-5.00% assembly weight. Replacement counterweights must resemble the original. Non-ferrous prohibited.
Legal, with conditions 1 class
Rebuild with replacement counterweights, crank pins, bearings and rods; total assembly weight within +/-5.00% of OEM; NON-FERROUS crank components prohibited; stroke and rod length may NOT change.
Legal, with conditions 1 class
Stroke and rod length may NOT change. +/-5.00% assembly weight. Non-ferrous metals prohibited.
Legal, with conditions 1 class
May be rebuilt or replaced provided counterweight shape, dimensions and material type, OEM stroke, rod length and journal diameters are retained; +/-5.00% assembly weight. · RAL.3.3
Legal, with conditions 1 class
Two-stroke: stroke and rod length changeable. Four-stroke: +/-5.00% weight.
Legal, with conditions 1 class
Variable stroke allowed so long as displacement limits are met; +/-5.00% weight.
Legal 3 classes
Stroke and rod length may be changed.
Legal 2 classes
Entire crankshaft assembly including connecting rods may be modified or aftermarket, total weight within +/-5.00% of OEM.
Legal 1 class
A two-stroke crankshaft assembly may be modified or aftermarket with stroke and rod length changed, and a four-stroke crankshaft may be modified or aftermarket within +/-5.00% of original weight, keeping the original stroke above 1600cc. · FREST.3.4, FREST.7.5
Legal 1 class
Two-stroke: stroke and rod length alterable. Four-stroke: +/-5.00% weight.
Aftermarket or modified crankshaft assembly: 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 13 of 20 answered, 6 with conditions