CASE STUDIES · PART TYPE
Carburetor and fluid-control castings: jets, sealing faces and internal passages
Our manufacturing roots go back to the Jinxiong motorcycle carburetor plant of 1998, and carburetor bodies, pump covers, throttle bodies and intake adapters are still core production. Below: what makes these parts hard, how we handle them, and every case we have published.
What makes these parts hard
Carburetors and throttle bodies are full of intersecting fuel and air passages and metering jets, wrapped in diaphragm sealing faces and flanges. Jet position sets the fuel-air ratio, diaphragm-face flatness decides whether the diaphragm seals, and drilled intersections and plug seats are the usual leak points. The parts are small and the passages dense, so a single pore can land right on a sealing face or a passage wall.
How we handle them
We lay out the parting line and machining datums around the bores and sealing faces, and finish the faces, jets and bores on CNC. Pressure and sealing features are 100% leak tested, every carburetor assembly goes over the flow bench, and jets are sorted by measured flow before assembly. In the cases published here, diaphragm faces are flat within 0.03 mm, jet position holds φ0.1 mm and idle flow is consistent within ±2%.
Carburetor & fluid control · Production cases8
Motorcycle Twin Throttle Body
Machined in two setups, the twin bores differed by up to 0.05 mm and the engine idled rough. One-setup boring and soft jaws now match them within 0.02 mm.
ADC12 (JIS H5302) · 约 520 gPZ27 Motorcycle Carburetor Assembly
A 0.1 mm jet shift moves idle flow by over 5%. One-datum machining, flow-sorted jets and 100% bench testing hold ±2%, with over a million delivered.
ADC12 (JIS H5302) · 约 420 g（总成）
PWK28 Carburetor Body
A gloss black coat magnifies every flow mark. Knit lines moved off the show faces, 100% pre-coat inspection and fixed blasting keep cosmetic rejects under 1%.
ADC12 (JIS H5302) · 约 300 g
Motorcycle Intake Manifold Adapter
Milled in two setups, the flanges ran 0.2 mm out of parallel and the gasket leaked. One-setup machining and 100% leak testing now hold 0.1 mm.
ADC12 (JIS H5302) · 约 150 g
Diaphragm Carburetor for Brush Cutters and Chainsaws
Diaphragm faces over 0.05 mm out of flat made engines stall hot. One-setup milling, low-stress holding and 100% leak and flow tests now hold 0.03 mm.
ADC12 (JIS H5302) · 约 180 g（总成）
Small Engine Carburetor Body
Drilled galleries opened casting porosity where they crossed, and plugs caused new leaks. Layout changes and 100% re-testing after plugging now pass over 98%.
ADC12 (JIS H5302) · 约 170 g
Diaphragm Carburetor Pump Cover
Far cavities cold-shut and hand deburring bent the 2 mm cover. Balanced runners and fixtured, pressure-controlled brushing now hold 0.03 mm flatness.
ADC12 (JIS H5302) · 约 45 g
Diaphragm Carburetor Body Casting (Unmachined)
Stock drifted 0.2 mm between batches and machining broke into porosity. Trend tracking, scheduled die care and targeted X-ray now hold 0.3 ± 0.1 mm.
ADC12 (JIS H5302) · 约 160 g（含浇排）Questions
Aluminum or zinc for a carburetor body?+
Both are used. Zinc casts denser and more accurately and has long been used for small carburetors; aluminum is lighter and cheaper in material but needs tighter porosity control. The carburetor bodies we produce today are all ADC12 aluminum, backed by 100% leak and flow testing.
Can you supply raw castings only?+
Yes. We can deliver as-cast bodies for you to machine; in the raw-casting case published here, machining stock holds at 0.3 ± 0.1 mm and scrap at the customer's machining is below 1%.
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