Sierra 18-97352 Carb Repair Kit Mercury 35-115 HP Outboard

If you've got a Mercury or Mariner outboard in the 35 to 115 horsepower range that's been sitting through a season, running rough at idle, or loading up and stalling, the carburetor is usually the first place to look. The Sierra 18-97352 carburetor repair kit gives you the wear parts you need to rebuild that carb and get clean fuel metering back. It's the gaskets, o-rings, seals, needle valve, and small hardware, all matched to the Mercury carb bodies used across this horsepower band.

Here's the honest version of what this kit is and isn't. It's a rebuild kit, not a whole carburetor. If your carb body is cracked or the bores are worn out, no gasket set fixes that. But nine times out of ten, a carb that won't idle right, floods, or won't hold a steady RPM just needs fresh soft parts. Ethanol fuel is hard on rubber and it varnishes up jets and passages. The o-rings swell, the needle valve tip wears a groove, and the gaskets take a set and start weeping fuel at the bowl seam. That's exactly what's in this kit to replace.

Fitment covers Mercury and Mariner outboards from 35 up to 115 HP, but do yourself a favor and verify against your engine serial number before you order. Mercury built a lot of carb variations across those years, and the safest move is to match the kit to your specific powerhead. This kit is built for the carbureted two-stroke motors in that range. It's not the part for the 4-stroke EFI 75 to 115 engines, since those don't run carburetors at all.

On the bench, take your time. Lay the carb parts out in order as you pull them so you know where every gasket goes. When you set the float, get the level right before you button it up. A float that sits too high floods the engine at idle and dumps raw fuel, and one that sits too low leans it out and makes it stumble off the line. Torque the bowl and body screws in a crisscross pattern, snug and even, so the gaskets seal flat without warping the castings. A lot of guys go around to about 45 inch-pounds and call it good.

When you set it back up, plan on resetting the idle mixture. On the 40 to 50 HP motors, roughly a turn and a half out on the mixture screws is a sane baseline to start from, then fine-tune it warm. And while you're in there, it's worth putting a fresh inline fuel filter on and checking the pickup in the tank. A rebuilt carb fed dirty fuel clogs right back up, so fix the whole fuel path, not just the carb.

Who needs a kit like this? Usually it's the owner of a well-used aluminum fishing boat or an older center console that picked up a Mercury two-stroke somewhere along the way. The motor starts fine, runs okay at cruise, but the idle hangs or dies, or it stumbles when you punch the throttle. That's classic carb-metering trouble, and a rebuild is a lot cheaper than a new carburetor or a trip to the dealer. If you can turn a screwdriver and follow a service manual for your engine, this is well within reach. Keep the old gaskets as templates until the new ones are seated, and don't reuse a stretched o-ring just because it looks fine.

Sierra has been supplying marine engine parts for decades, and their gear is engineered to meet or exceed the original equipment part it replaces. That means the seals and gaskets are cut for the same fit and the needle valve seats the same way the factory part does. For a shop or a do-it-yourself owner, that's the assurance you want before you crack open a carburetor on a running motor. Get the right kit for your serial, work clean, set your float and mixture, and this is a straightforward afternoon job that brings an old outboard back to a crisp idle.