Berryman B-12 Chemtool Carburetor, Choke & Throttle Body Cleaner

Shake the can, insert the straw into the carburetor passage, and spray in short bursts — the formula flashes through gum and varnish and evaporates within a minute, leaving passages dry and ready for air-gun blow-out. The label claim "dries fast, leaves no residue" is chemistry-consistent per SDS §9 (boiling range 133–343°F, evaporation rate 5.1× n-butyl acetate), and the "safe on catalytic converters and oxygen sensors" claim holds up against the SDS §3 composition (no chlorine, no silicone, no metallic additives that would foul a sensor). Community evidence on small-engine and motorcycle forums consistently reports single-pass clearing on mildly-to-moderately gummed carbs; the honest limitation is that aerosol spray-in-place can't reach years of brown-lacquer varnish in passages — those carbs need an overnight soak in a dedicated carb-dip solution or ultrasonic cleaning.

The right buy for a home mechanic with a sit-started seasonal small engine — lawnmower, generator, outboard — that stumbles on idle after a winter of stale fuel, or a motorcycle restorer doing a first-pass cleanup before deciding whether the carb needs a full strip and dip. 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 requires an overnight soak in a carb-dip solution like Berryman's own B-9 Chemdip, not an aerosol spray. Also skip if you need a low-emission solvent for indoor or California-restricted use: although the product is CARB-compliant by regulatory definition (because acetone is CARB-exempt, not because the formula is low-solvent), the absolute volatile organic mass to atmosphere is around 600 grams per liter — what the lungs and the atmosphere actually see is high even by carb-cleaner standards.

The Berryman SDS assigns a DANGER signal word with H222 (extremely flammable aerosol), H280 (gas under pressure; may explode if heated), H315 (skin irritation), H319 (serious eye irritation), H336 (may cause drowsiness or dizziness — narcotic effects from acetone and toluene), H361d (suspected of damaging the unborn child — toluene driver), H373 (may cause damage to blood and central nervous system through prolonged or repeated exposure), and H402 (harmful to aquatic life). The Prop 65 warning is required because toluene is listed by California for developmental toxicity. The lungs PPE tier translates to recommended rather than required because the §2 mixture classification does not include H335 (respiratory irritation), H331 (toxic if inhaled), or H334 (respiratory sensitization) — the chemistry does not force the higher tier. SDS §7 directs use only outdoors or in a well-ventilated area; SDS §8 directs an organic-vapor cartridge respirator when ventilation is inadequate or for prolonged or repeated application, safety glasses with wrap-around lens or goggles, and chemical-resistant gloves. The CARB-compliant designation here is a regulatory accounting result driven by acetone's exempt status — not a low-emission product profile; absolute solvent emissions are around 600 g/L. CARB-compliant status reflects exempt-compound accounting (acetone is CARB-exempt under the consumer-product regulation); absolute VOC measured by the federal method is approximately 600 g/L — ventilation requirements apply regardless of CARB compliance status. Environmentally, the product is drain-destined when used (drips off the carb to the workbench or ground); the SDS Section 12 confirms the solvents are "rapidly degradable" in aerobic surface conditions but "very mobile in soils — may contaminate groundwater," so SDS §13 directs disposal away from soil and storm drains. Flash point of −7°C closed-cup means SDS §7 directs keeping the product away from heat, sparks, and open flames during and after application.