CRC Carb & Choke Cleaner (12 oz aerosol)

Insert the straw into the carburetor passage, spray short bursts (5–10 seconds), let the formula work the gum loose, and blow out with compressed air. The fast-evaporating formula dries passages in under a minute, and the high active fraction means one can typically handles a single small-engine carb cleaning. Forum consensus across Lawn Mower Forum, Briggs & Stratton service threads, and vintage motorcycle restoration communities places CRC #03077 alongside Berryman B-12 as the two go-to aerosol options for moderate-to-heavy varnish. It does not replace a strip-and-soak for years-old lacquered deposits, but for sit-started small engines and seasonal-storage gum, the formula clears pilot jets and emulsion tubes reliably without leaving residue.

The right buy for a home mechanic dealing with a small-engine carburetor (lawnmower, generator, snowblower, outboard) that stumbles or won't idle after seasonal storage. Also the right pick for owners who care about Prop 65 disclosure transparency and CARB compliance — the SDS is publicly available with full ingredient disclosure at a predictable URL, which is unusual for the category. Skip it if the carburetor has been sitting with stale fuel for multiple years and shows heavy brown-lacquer varnish in the passages — that level of deposit needs an overnight strip-and-soak in a dedicated carb-dip solution or ultrasonic cleaning, not aerosol spray. Skip it if you're cleaning a fuel-injected throttle body — CRC sells a separate product (#05078) for that use case.

The product carries the DANGER signal word, driven by extreme flammability (H222, flash point < −17.8 °C) and aspiration toxicity (H304 — may be fatal if swallowed and enters airways). The 2017 SDS classifies skin irritation (H315), serious eye irritation (H319), and narcotic-effect inhalation (H336). SDS §8 specifies safety glasses or goggles and lists nitrile gloves among acceptable materials for spray application; the aerosol form combined with high vapor pressure (5061 hPa) is the basis for SDS §8 directing use in a well-ventilated area, with an organic-vapor cartridge respirator when engineering controls are inadequate. The label carries the California Proposition 65 warning ("Cancer and Reproductive Harm") — confirmed by the rear panel image and SDS Section 15, which lists trace acetaldehyde, benzene, cumene, ethylbenzene, naphthalene, and toluene present as impurities in the petroleum-derived heptane fraction. Do NOT induce vomiting if ingested — seek immediate medical attention per SDS first-aid guidance.

The CARB-compliant designation here is a regulatory-accounting outcome: the dominant solvent is exempt under both EPA 40 CFR 51.100(s) and California's Consumer Products Regulation for carb cleaners, which is why the SDS reports a regulatory VOC of 9.2% by weight. Absolute solvent emissions to the atmosphere are still in the high-VOC bracket (~700 g/L) — what the lungs and the atmosphere actually see is not captured by the regulatory-VOC number. The H411 chronic aquatic toxicity classification (Cat 2) means residue should not be discharged to drains, sewers, or waterways; use absorbent material on spills and dispose as hazardous waste. SDS Section 12 notes no degradability data is available, so no biodegradable credit applies. The SDS revision is dated 2017-10-04 — more than 8 years old — and a targeted re-fetch on 2026-05-10 confirmed CRC has not yet published a newer public revision; reformulation between then and now cannot be ruled out.