Walbro Carburetor Jet Size Chart & Drill Size Guide
This guide provides a practical reference for Walbro carburetor jet and passage sizes and drill sizes commonly used for cleaning, checking, and careful carburetor service work. Walbro carburetors include many different families and small-engine applications, so this guide should be used as a practical drill-size reference rather than a guaranteed manufacturer specification.
About Walbro Carburetors
Walbro carburetors are widely used on small engines, chainsaws, trimmers, blowers, recreational equipment, and other power-equipment applications. Common Walbro carburetor families include chainsaw carburetors, trimmer and blower carburetors, and related small-engine carburetor designs.
Unlike some automotive carburetors that use removable main jets with familiar numbered references, many Walbro small-engine carburetors use very small calibrated passages, check valves, mixture circuits, and replaceable service parts. In many cases, cleaning or rebuilding the carburetor is safer than drilling a fuel passage. Always verify the specific Walbro model, service manual, and application before cleaning, checking, or modifying any jet or passage.
Which Drill Set Is Right for Walbro Carburetor Work?
For Walbro carburetor cleaning, checking, and careful reference work, choose a drill set based on the small passage or jet diameter range you expect to work with. Use extra caution before modifying any fuel-metering passage.
Best Starting Point for Many Small Walbro Passages: 20 Pc Selected Sizes Carburetor Jet Drill Set
Covers selected sizes from .0135" through .071", including many small metric and numbered drill sizes useful for checking, cleaning, and comparing small carburetor passages and jet openings.
Need More Continuous Numbered-Drill Coverage?
The 25 Pc #75–#51 Carburetor Jet Drill Set gives a broader numbered-drill range for general carburetor jet checking, cleaning, and careful tuning.
Want Backup Drills in Each Size?
The D7 50-piece #80–#56 set includes 25 sizes with two drills per size, useful when working with very small, brittle carbide drills and small carburetor passage ranges.
Working on Larger Jets or Multiple Carburetor Brands?
If you work on larger carburetor jets, Holley-style ranges, Rochester/Quadrajet applications, Weber main jets, or several different carburetor brands, compare the full collection before ordering.
Important: carbide drills are brittle precision tools. Use light pressure, keep the drill straight, and avoid enlarging passages unintentionally during cleaning.
Walbro Passage & Drill Size Reference
Walbro carburetors may use small calibrated passages and fuel circuits rather than a simple universal numbered jet chart. Because of this, the sizes below should be treated as practical drill-size references for comparison and cleaning work, not as official Walbro jet specifications.
The Nearest Drill Size Reference column shows the closest practical drill size or drill range for comparison. It is meant for checking and reference only; always verify the actual carburetor model and service information before modifying anything.
| Approx. Diameter | Metric Reference | Nearest Drill Size Reference |
|---|---|---|
| 0.0135" | 0.35 mm | #80 |
| 0.0160" | 0.40 mm | #78 |
| 0.0200" | 0.50 mm | #76 |
| 0.0240" | 0.60 mm | #73 |
| 0.0250" | 0.64 mm range | #72 |
| 0.0260" | 0.65 mm | #71 |
| 0.0280" | 0.70 mm | #70 |
| 0.0290" | 0.75 mm | #69 |
| 0.0315" | 0.80 mm | 1/32" |
| 0.0330" | 0.85 mm | #66 |
| 0.0350" | 0.90 mm | #65 |
| 0.0370" | 0.95 mm | #63 |
| 0.0390" | 1.00 mm | #61 |
| 0.0610" | 1.55 mm | 1.55 mm range |
| 0.0650" | 1.65 mm | 1.65 mm range |
| 0.0670" | 1.70 mm | #51 range |
| 0.0690" | 1.75 mm | 1.75 mm range |
| 0.0710" | 1.80 mm | 1.80 mm range |
Note: This chart is an approximate drill-size reference based on small carburetor passage and selected drill sizes. It should not be treated as an official Walbro specification or a recommendation to enlarge any passage.
Using Drill Sizes for Walbro Carburetor Work
Precision drill bits may be used in carburetor work for checking approximate passage size, comparing openings to known drill diameters, and carefully cleaning soft deposits from accessible brass parts. However, Walbro small-engine carburetors often include delicate fuel-metering circuits where aggressive drilling can permanently damage the carburetor.
For many Walbro carburetors, a rebuild kit, proper cleaning, compressed air, carburetor cleaner, or replacement service parts may be more appropriate than enlarging a passage. When using a drill, use it as a reference or gentle cleaning tool rather than as a first-choice method of modification.
Practical Drill Size Range for Walbro Carburetors
Many Walbro small-engine carburetor passages are small, so the 20-piece selected-size set may be a practical starting point for careful checking, cleaning, and comparison work. The D7 50-piece #80–#56 set may also be useful when backup drills are important because very small carbide drills are brittle.
If you are unsure which set is best, compare the carburetor jet drill sets before ordering. For larger automotive carburetor jets, a larger range such as the HS1 .040"–.125" set may be more appropriate.
Tips for Walbro Carburetor Cleaning and Jet Work
- Use light pressure when working with carbide drills
- Keep the drill straight to avoid making a passage oblong
- Use drills carefully as size references or gentle cleaning tools
- Do not force a drill through a calibrated fuel passage
- Check the specific Walbro carburetor model and service information before modifying anything
- Consider rebuilding or replacing service parts rather than enlarging fuel passages
- When in doubt, replace the carburetor or service part rather than over-drilling it
Conclusion
Walbro carburetors often use small calibrated passages and fuel-metering circuits, so careful cleaning and verification are more appropriate than aggressive drilling. Use this chart as an approximate drill-size reference, verify the specific carburetor model before modifying anything, and choose the drill set that best matches the range of sizes you need.