If you're looking for a 9.9 boat motor used, you've likely realized these things are the absolute sweet spot for small watercraft. They're the "Goldilocks" of the outboard world—powerful enough to get a 12-foot tin boat on a plane, yet light enough that you won't throw your back out trying to clamp it onto the transom. Plus, they're the legal limit for a lot of restricted horsepower lakes, which makes them incredibly popular and, honestly, a little hard to find at a fair price.
Buying a used motor can be a bit of a gamble if you don't know what to look for. I've spent way too many afternoons looking at engines in people's driveways that "ran great last year" only to find out they're essentially expensive boat anchors. To help you avoid that headache, I've put together some thoughts on how to navigate the used market, what to look for during an inspection, and how to make sure you're getting a deal that actually makes sense.
Why everyone wants a 9.9
The obsession with the 9.9 horsepower rating isn't random. It's almost entirely driven by regulations. Many smaller lakes across North America have a 10-horsepower limit. By labeling these engines as 9.9, manufacturers give boaters the maximum allowable power without breaking the rules. Because of this, the demand for a 9.9 boat motor used is always high. You aren't just competing with fisherman; you're competing with sailors looking for a kicker and families with small pontoon boats.
Another reason they're so popular is portability. Most 9.9s, especially the older two-stroke models, weigh somewhere between 75 and 85 pounds. You can realistically haul that from your garage to your trunk and then onto the boat by yourself. Once you jump up to a 15 or 20hp, things start getting significantly heavier, and you're suddenly in "engine hoist" territory.
Where to start your search
When you start hunting for a 9.9 boat motor used, Facebook Marketplace and Craigslist are usually the first stops. They're great because you can see local listings, but you have to be fast. A well-priced Yamaha or Honda 9.9 will often sell within hours of being posted.
Don't overlook local marinas, though. Sometimes people trade in their older outboards when they upgrade to a new boat package. While a marina might charge a bit more than a guy on the street, they often do a basic service on the motor before selling it, which gives you a bit more peace of mind. Plus, they might even offer a 30-day "it won't blow up" warranty, which is rare in the private market.
Sorting through the listings
When you're scrolling through ads, pay attention to the photos. If the motor is sitting in a clean garage and looks well-maintained, that's a good sign. If it's lying in the tall grass behind a shed, proceed with caution. Also, look at the propeller. A chewed-up prop usually means the owner wasn't too careful about where they were running the boat, which could mean there's internal damage from hitting rocks or stumps.
The "Must-Check" list before you hand over cash
Once you find a potential motor, you've got to see it in person. Never, under any circumstances, buy a used outboard without seeing it run. If the seller says they don't have a way to start it, bring your own "ear muffs" (the water flusher attachment) or a large plastic trash can to fill with water. If they still refuse to let you start it, just walk away. It's not worth the risk.
The cold start
When you arrive, feel the engine block. Is it warm? If it is, the seller might have started it up before you got there to hide a difficult cold-start issue. A good 9.9 boat motor used should be able to start within three or four pulls even when it's stone cold. Once it's running, it should settle into a steady idle without you having to mess with the choke or the throttle constantly.
Look for the "Pee Stream"
This is boater-speak for the cooling water tell-tale. You want to see a strong, steady stream of water shooting out the back of the motor. If it's just a dribble or nothing is coming out at all, the water pump impeller is likely shot. Replacing an impeller isn't the end of the world—it's actually a common maintenance item—but it tells you the owner might have been neglecting the cooling system.
Check the gear oil
Ask the seller if you can unscrew the lower unit drain plug just a tiny bit. You don't need to drain the whole thing; you just want to see a drop or two. If the oil looks like chocolate milk, that means water is leaking into the gearcase. This usually implies a bad seal, which can lead to a very expensive repair if the gears have started to rust.
Two-stroke vs. Four-stroke
This is the eternal debate when looking for a 9.9 boat motor used.
Older two-strokes are lighter and simpler to fix. They have a certain "zip" to them and are generally more "bulletproof" if they've been sitting for a while. However, you have to mix gas and oil, they're louder, and they smell like well, like a two-stroke. If you're using the motor for short trips or on a boat where weight is a major concern, a two-stroke is a fantastic choice.
Four-strokes are the modern standard. They're incredibly quiet—at idle, you can barely hear them—and they're much better for trolling because they don't "load up" with oil at low speeds. They also use straight gasoline, which is way more convenient. The downside? They are heavier and have more moving parts, meaning things like valves and timing belts need to be checked eventually.
Brand reputations to keep in mind
While any motor that's been cared for can be a winner, some brands just have a better track record in the 9.9 category.
- Yamaha: Often considered the gold standard. Their 9.9s are legendary for reliability. Parts are easy to find, and almost every mechanic knows how to work on them.
- Honda: These guys were the pioneers of the four-stroke outboard. Their 9.9s are incredibly smooth and quiet. They're a bit heavier, but they last forever.
- Tohatsu: A lot of people don't realize that Tohatsu actually makes the small engines for several other big brands (like Mercury and older Evinrudes). They are solid, no-nonsense motors that offer great value.
- Mercury: Very popular with a massive dealer network. Their newer EFI (Electronic Fuel Injection) models are great, though older carbureted versions can be a bit finicky if the fuel isn't kept fresh.
Negotiating the price
When you're looking at a 9.9 boat motor used, don't be afraid to haggle a bit, but be realistic. If the motor is a 2018 model in pristine condition, don't expect to get it for half price. However, if you notice things like a cracked cowling, a bent prop, or if it hasn't had a tune-up in years, use those as leverage.
A good trick is to ask when the spark plugs and fuel filter were last changed. Most sellers won't have an answer, which gives you a reason to say, "Look, I'm going to have to spend $150 on a full service and parts as soon as I get this home, so can you do $200 less on the price?"
Maintenance after the purchase
Once you finally get that motor home, do yourself a favor and do a full "baseline" service. Change the spark plugs, swap the gear oil, and put in a fresh fuel filter. If you don't know when the water pump was last replaced, just do it. It's cheap insurance against overheating your "new-to-you" engine in the middle of a lake.
Also, always use an ethanol-free fuel if you can find it. Small carburetors on 9.9s have tiny passages that get gummed up very easily by the corn-syrup-like residue that modern pump gas leaves behind. If you have to use regular gas, make sure you use a fuel stabilizer and run the carburetor dry if the motor is going to sit for more than a couple of weeks.
Buying a 9.9 boat motor used is a great way to get on the water without the "brand new" price tag. It takes a little bit of patience and a discerning eye, but once you find that perfect little kicker that purrs like a kitten, you'll realize it was worth the effort. There's nothing quite like the feeling of pulling the cord and hearing that engine roar to life, knowing you're about to have a great day on the water.