Free printableMeasure partsTSP-ME-17
Measuring exhaust stud spacing and port size
Stud spacing and port bore decide whether an exhaust bolts on. Measure both against a true-size grid before ordering.
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TSP-ME-17 · version v1.0 · September 2026. Opens in your browser's PDF viewer, where you can print directly.
The problem it solves
Exhausts and their gaskets are listed by machine model, which is useless when your model is not listed. What actually determines fitment is the distance between the two studs and the diameter of the port — two measurements that take a minute and that almost no listing quotes.
The exhaust joint at the cylinder head is the one place on these machines where a small dimensional error is immediately obvious: the studs either line up or they do not. That makes it one of the easier things to get right, provided you measure before you buy.
The gasket is worth measuring at the same time, because it is a separate part with its own dimensions and it is the commonest cause of a joint that blows after being disturbed. A gasket that is the right outside diameter but the wrong bore will restrict the port; one that is the right bore and too thin will not seal.
Both measurements go on the true-size grid below, so you can take them with nothing but the printed sheet.
The mistakes this sheet exists to prevent
- Measuring stud spacing from the outside edges rather than centre to centre.
- Reusing a crushed exhaust gasket, which is the commonest cause of a blowing joint.
- Ordering an exhaust without checking the rear mounting point as well as the flange.
- Ignoring the port bore, so a smaller-bore gasket restricts the exhaust.
- Overtightening flange nuts to cure a blow, which strips the studs out of an alloy head.
Who it is for
- Anyone replacing an exhaust or a header gasket
- Owners chasing a blowing exhaust joint
- Anyone fitting an exhaust that was not listed for their machine
What is on it
- A true-size grid for stud spacing and port bore
- The three measurements an exhaust needs, including the one at the back
- Gasket types and what to record
- A blowing-joint checklist
How to use it
- 01Check the calibration rule before measuring against the grid.
- 02Measure stud spacing centre to centre, not edge to edge.
- 03Measure the rear mounting point as well as the flange — an exhaust has to fit at both ends.
- 04Always fit a new gasket. They are designed to crush once.
Use it with the registry
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Free to print, copy, and share — including in forums, clubs and workshops. If you find a mistake on this sheet, tell us and it gets corrected. Quote TSP-ME-17 and the version so we know exactly which sheet you mean. All printables.