Carburetor Adjustment Tool Finder

Match the shape on your carburetor’s adjustment screws, then pick the tool — some carbs have no user adjustment at all. Covers the Single D, Double D, Pac-Man and 7-tooth spline profiles used on 2-stroke chainsaws, string trimmers, blowers and edgers, with brand quick-picks for Stihl, Husqvarna, Echo, Poulan, Ryobi/Homelite, Craftsman and MTD/Troy-Bilt/Toro, and multi-tip kits worth checking for the profiles a consumer tool actually exists for.

What tool do I need to adjust my carburetor’s idle mixture screws?

It depends on the shape of the screw head. Match it to one of the profiles above — Single D, Double D, Pac-Man, or a 7-tooth spline — then check the multi-tip kits below (their tip contents are not verified by WhatSizeBolt, so check the listing photos before buying). Some engines have no mechanical adjustment at all: Stihl M-Tronic replaces the carburetor’s H, L and LA screws with a solenoid valve. On other carburetors, some have a fixed idle jet — only the high-speed needle and the idle-speed screw adjust.

Does Walbro or Zama sell carburetor adjustment tools?

Walbro states "Walbro is no longer allowed to produce or sell carburetor adjustment tools," citing EPA and California Air Resources Board emissions regulations — its tools are "only available through authorized OE dealers or from the Original Engine Manufacturers," and its "500-505 tool kit as well as all other individual tools are still available through your nearest Walbro Central Warehouse Distributor." Special adjustment tools for Zama carburetors "are only available to licensed repair shops or technicians from the manufacturer of the unit" — meaning the equipment maker, not Zama, supplies its own dealers; "Zama does not sell these tools."

Why does my chainsaw have no carburetor adjustment screws at all?

Only one common case genuinely means zero mechanical screws: Stihl’s M-Tronic system replaces the carburetor’s H, L and LA screws with a solenoid valve — look for "C-M" or "C-EM" in the model name, or "M-Tronic" on the saw or listing. If your saw has at least one H, L or LA adjustment screw, it is not M-Tronic; some simpler carburetors just have fewer adjustable circuits, such as a fixed idle jet that still leaves a high-speed needle and an idle-speed screw to turn.

Is it legal to adjust my small engine’s carburetor?

Adjusting within the factory limiter-cap range is normal tuning. Emissions limiters exist by law, and removing or defeating the limiter caps to adjust beyond that range may violate EPA/CARB emissions rules for your equipment. If you are not sure what your equipment allows, use a dealer.

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