Record starter pinion outside diameter separately from tooth count. Include the dimension’s units, identify whether it is a catalog value or a sample measurement, and preserve qualifiers such as “approximately.” One diameter measurement does not establish gear pitch or confirm a replacement snowmobile starter’s fitment.
Copy the catalog dimension without changing its meaning
A useful dimension entry names the feature—not just a number. Write “pinion outside diameter: approximately 14.6 mm,” rather than “gear size: 14.6.” Keep tooth count in a separate field.
The supplied catalog provides these examples:
| Starter reference | Catalog pinion outside diameter | How to record its status |
|---|---|---|
| 0745-052 | Approximately 29.1 mm, identified as tooth-tip outside diameter | Catalog value; approximate |
| 7902-987 | Approximately 14.6 mm | Catalog value; approximate |
| 3020-364 | Approximately 11.7 mm | Catalog value; approximate |
| 2410889 | Approximately 28.8 mm | Catalog value; approximate |
| 0451411 | Approximately 11.7 mm | Catalog value; approximate |
These are transcribed specifications, not new measurements or a list of interchangeable starters. For example, the 7902-987 starter listing identifies a candidate reference to investigate; the dimension still belongs in a broader application review.
Do not turn “approximately 14.6 mm” into an exact requirement of “14.600 mm.” The supplied information does not establish a dimensional tolerance for these entries.
Keep measured values in a separate record
If a qualified person supplies a measurement from a reference unit, label it as a sample measurement rather than overwriting the catalog entry. A useful record includes:
- Unit identity: the starter marking or reference, and which sample was measured.
- Feature: pinion outside diameter, with the tooth-tip feature clearly identified where applicable.
- Measurement points: the two points or faces used, supported by an annotated photo or sketch when available.
- Value and units: transcribed exactly as supplied.
- Origin: a physical measurement, supplier drawing, catalog entry, or unconfirmed estimate.
- Supporting record: the drawing revision, dated measurement note, or labeled photograph.
A photograph can identify the visible feature, but it is not a scale drawing. Do not assign an outside diameter from an unscaled image.
A compact comparison template
| Field | Entry to complete |
|---|---|
| Starter reference and sample identity | Exact marking and sample description |
| Catalog outside diameter | Value, units, and approximation—or “not supplied” |
| Measured outside diameter | Separately supplied value and units—or “not measured” |
| Measured feature and points | Description plus annotated view if available |
| Source | Catalog, drawing revision, or measurement record |
| Tooth count | Separate confirmed value—or “unconfirmed” |
| Open question | Missing units, unclear feature, or conflicting values |
This keeps a published specification, an observation, and an unresolved question from becoming one apparently confirmed number.
Keep units explicit, even for a US inquiry
The catalog examples above use millimeters. Retain mm when copying them into an inquiry or comparison sheet; do not leave the unit implicit because the buyer or supplier is in the United States.
If a supplied sample measurement uses inches, mark it as in and retain that original entry. If a converted value is also included, label it as a conversion rather than a second measurement. Do not add precision or imply a tolerance that the original record does not provide.
When a supplier gives only a bare number, ask for the unit and feature definition before comparing it with the catalog.
Leave missing diameters unresolved
The supplied 0645-183 entry does not reliably establish tooth count or tooth-tip outside diameter. It includes a drive-end notation of approximately 9.5 × 6.5 mm, but that notation must not be relabeled as pinion outside diameter.
Likewise, a listed tooth count does not fill a missing diameter field. Record “outside diameter not supplied” and request a clearly identified drawing dimension or sample measurement.
Use a discrepancy as a question, not a fitment verdict
If a measured value differs from a catalog entry, retain both with their sources. Ask the supplier to confirm that both records describe the same feature on the same reference and to explain which specification applies to the proposed item.
Do not derive gear pitch or approve a replacement from that measurement. Snowmobile starter motor fitment review also involves the exact machine model and year, original reference, mounting arrangement, terminals, rotation, and electrical specifications. Outside diameter is one documented check within that review—not a substitute for it.