# Mower, Chainsaw and Generator Plugs Before Summer **By Sawley's Auto and Marine** · 2026-09-26 Spring is when the mower comes out, the chainsaw gets its first run of the year, and the generator gets tested because the fire plan says it should. All three spent winter in the shed with the same stale fuel and the same tired plug they went in with, and every October the small engine that will not start is the most common problem on the peninsula. ## Why the plug is the first thing to check A small engine has a simple ignition, a small plug, and a hard life: it runs hot, at full throttle, in dust, on fuel that has often sat for months. The plug is cheap, it comes out with a socket and a minute, and it is the single most likely thing to be wrong with an engine that cranks and does not fire. The ritual is worth adopting: **new plug at the start of every season** on the mower, the chainsaw, the trimmer and the generator. It costs less than a coffee each and it saves the hour of pulling on a starter cord. Pull the old one and read it before you throw it away. Black and sooty is a rich mixture or a choked air filter, which is the other spring classic. Oily and wet on a two-stroke is too much oil in the mix. White and blistered is running hot, usually a lean carburettor or a blocked cooling fin. The colours are the same as they are on an outboard, and the full reading guide is in our post on [reading and choosing spark plugs](/blogs/guides/outboard-spark-plugs-reading-and-choosing-ngk). ### Mowers and ride-ons Briggs and Stratton, Honda, Kohler and Kawasaki engines power most of the mowers in Australia, and each has a small family of plugs it uses across its range. The ride-on with a twin-cylinder engine has two plugs, and they are changed as a pair. Gap them to the figure the engine maker gives — the plug box often says pre-gapped, and it often is not quite — and do not overtighten into an aluminium head. We have put NGK's complete listing for mowers and ride-ons on the site, by machine make and by engine code, starting with [Husqvarna, Toro, Cub Cadet, John Deere, Honda and the other major makes](/pages/ngk-spark-plugs-mowers-major-makes), with the Masports, Victas and Rovers on their own page. ### Chainsaws, trimmers and blowers The two-stroke handhelds run a compact plug and they foul it readily, because they idle a lot, they run on premix, and the premix is not always right. A chainsaw that has lost its top-end power or four-strokes at full throttle is usually a plug or a mix problem before it is anything else. Get the ratio right — most modern saws are 50:1, the older ones vary — and use a two-stroke oil made for air-cooled engines, which is a different product from the outboard oil. Our guide to [two-stroke premix ratios](/blogs/guides/two-stroke-premix-ratio-older-outboards) covers the arithmetic. The plug listing for Stihl, Husqvarna, Echo and the rest, back to the old magneto saws, is on our [chainsaw spark plug page](/pages/ngk-spark-plugs-chainsaws). Before the fire season, the chainsaw matters more than it does the rest of the year. If it is part of your fire plan, it needs to start on the first pull in November, and that means a plug, fresh fuel and a sharp chain in October. ### Generators A generator is the engine that gets the least use and is needed most. It sits for months, and then the power goes out on a forty-degree day with the fire front on the horizon and it is expected to start. It will, if it has been run under load for half an hour every month or so, on fresh fuel, with a plug that is not two years old. It will not if it has been left. Put the plug change on the same day as the smoke alarm batteries; the generator plug listing by make — Honda, Generac, Yamaha, Kohler and the others — is on the [generator spark plug page](/pages/ngk-spark-plugs-generators). For small engines that are sold on their own and fitted to a hundred different machines — the loose Briggs, Honda and Kohler engines — the listing by engine code on the small engines page is the one to use when the machine is not in the other lists. ### The other spring jobs The plug is first, but it is not everything. Drain the old fuel and put fresh in; petrol that sat all winter is the second most common reason a small engine will not start. Clean or replace the air filter, because a foam filter that has been in a dusty shed is choking the engine. Check the oil on the four-strokes and change it if it is dark. Sharpen the chain and the blades. Ten minutes with each machine in September saves a wasted Saturday in October. Every plug code in the listings above links straight to the plug in our [NGK spark plug range](/collections/ngk-spark-plugs-marine-automotive-small-engine-ignition), which covers the small engine and outdoor power plugs alongside the marine and automotive ones. If a machine will not start after a new plug and fresh fuel, the carburettor has usually gummed up over winter, and that is worth a phone call: ring [0412 532 984](tel:+61412532984). **Tags:** Guides, Spark Plugs --- > Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/blogs/guides/mower-chainsaw-generator-spark-plugs-before-summer)