When you look into jet skis, you may come across the words 2-stroke and 4-stroke and wonder what they mean?
Is a 4-stroke better than a 2-stroke, what is even the difference between them and should you care?
In this post, I want to answer these questions and more, while also figuring out if you should get a 2-stroke or 4-stroke jet ski.
What Is A 2-Stroke Jet Ski?
A 2-stroke jet ski refers to the type of engine that is used to power it.
The 2-stroke name comes from how many strokes (down then up) of the piston are needed to perform before combustion.
What makes 2-strokes so unique is how things are simplified. 2-strokes mix the gas and the oil to cut down on parts and to save a step. The piston is lubricated when the air and gas/oil mixed is allowed in, and when the piston goes up it fires to repeat the cycle.
In the process of saving a step, some gas/oil mix can escape through the exhaust. This was one of the biggest reasons why 2-strokes are not popular on jet skis anymore, as the exhaust of jet skis is dumped into the water.
Since the oil is burned with the gas, you don’t change the oil in a 2-stroke, you only add oil. Most 2-stroke jet skis only needed the oil added every few tank fill ups and had their own tank to hold the oil.
What Is A 4-Stroke Jet Ski?
What makes a 4-stroke engine different from a 2-stroke engine is how the oil is handled. In a 2-stroke, the oil is mixed with the gasoline, but in a 4-stroke, the oil is not mixed.
Here is how a 4-stroke engine works.
Since 4-stroke engines don’t mix the oil, they instead recycle it and the oil must be changed every year or every 50 hours, whichever one comes first.
4-strokes have become the most common engine type used by jet skis and most vehicles like your car today.
How To Know If You Have A 2-Stroke or A 4-Stroke Jet Ski?
The easiest way to determine if you have a 2-stroke jet ski or a 4-stroke jet ski is by looking for a dipstick.
Only a 4-stroke jet ski will have a dipstick located on the top or near the top of the engine as shown in the picture below.
Another way to determine is by the age of your jet ski. The last two digits of your VIN tell you the year of your jet ski. The VIN is located at the rear on the right of your jet ski, either on top or below the rub rail.
The First 4-Stroke Jet Skis
Yamaha waverunner was the first to release a 4-stroke in May 2002, so any Yamaha made in 2001 or older will be a 2-stroke. The last sit-down jet ski from Yamaha to have a 2-stroke engine was in 2012 with the WaveRunner VX700S, the standup jet skis had a 2-stroke engine until 2020 as the 2021 SuperJet standup jet ski went with a 4-stroke engine. So any sit-down jet ski Yamaha made in 2013 or newer will be a 4-stroke and the standup’s joining in 2021.
Sea-Doo first made a 4-stroke jet ski in 2002 and the last 2-stroke ever made by Sea-Doo was 2007. So any Sea-Doo that is 2008 or newer will be a 4-stroke, and any Sea-Doo made before 2002 will be a 2-stroke. Also to note, that every Sea-Doo with a 4-stroke engine also got closed loop cooling too and still holds true today.
The first Kawasaki jet ski with a 4-stroke was in 2003 and the last 2-stroke ever made by Kawasaki was in 2016 as they released their new 4-stroke standup in 2017.
2-Stroke Vs. 4-Stroke – What’s Better?
Both 2-stroke and 4-stroke each have their advantages but overall, 4-stroke is better and what you find in most jet skis today.
2-strokes are being phased out because they pollute more and don’t last as long as the 4-stroke jet skis.
It’s not all bad things with 2-stroke, here are the pros and cons of both 2-strokes and 4-strokes.
- Lighter and more torque.
- Simpler designs.
- Easier to work on.
- 2-stroke was the most common engine in the first jet skis until the early 2000s when we started getting 4-strokes.
- More playful. Since the engines were smaller, the jet skis were smaller, which made them more playful. Just check out the Sea-Doo HX if you want to see how playful a jet ski can really be.
- They pollute more because they burn the oil.
- Many places have banned 2-strokes because of how much they pollute.
- Louder and built when sound dampening wasn’t a huge concern, so the noise pollution they make also is another reason they’re banned on many lakes.
- 2-strokes are being phased out, if not completely by now, so new parts are hard to find if not impossible by the manufacturer. The 3rd party aftermarket parts are not as thriving for jet skis as it is for cars, so most parts can only be found used online from places like eBay.
- Messier engine, makes more of a mess in the engine compartment due to it burning oil.
- Fouls spark plugs more often due to burning oil. It was so bad that most 2-stroke came with a spark plug changing kit under the seat.
- Not as reliable, it was not uncommon to do a whole engine rebuild on a 2-stroke before 300 hours.
- Burns more gas as most 2-stroke were carbureted. A few 2-stroke did get fuel injection, but it was primitive and never that great compared to what 4-strokes have today. It was so bad that I tell people to avoid any Sea-Doo that has a “DI” or “RFI” in the name, those suckers are cursed.
- More reliable than 2-strokes, we’re seeing 4-strokes go over 500 hours easily, with some even hitting 1,000 hours.
- Easier to get parts for 4-strokes compared to 2-strokes.
- Doesn’t pollute nearly as much.
- Better on gas, with many models today having driving modes like ECO.
- Reach higher speeds than 2-stroke. Given enough time 2-stroke could have gotten to these higher speeds but since they’re phased out you want to get a 4-stroke if you aim to go fast.
- 4-strokes are more stable than 2-strokes because the engine are bigger, so the jet skis needed to be bigger.
- 4-stroke are bigger and less nimble than 2-strokes, but the Sea-Doo Spark and Yamaha EX are quite nimble even though they’re 4-strokes. Though, it seems most people want a more stable jet ski, and thus what we see most of.
- More complicated and more computers. A 2-stroke is a lot simpler in comparison to a 4-stroke. There are a few things customers can’t do to fix a modern 4-stroke jet ski without having to take it to the dealership.
Should You Buy A 2-Stroke Jet Ski?
Since I’ve started this website back in 2014, my stance has been to avoid 2-strokes. It’s even the main point of my what to look for in a used jet ski post.
2-strokes are phased out even more since then, and parts are only getting harder to find.
Unless you like working on your jet skis and can get parts for a used 2-stroke, then it’s not worth it for the average jet ski owner.
Most people want a jet ski that is reliable, lasting, great on gas, comfortable, full of tech, and great for the whole family, and only a 4-stroke can offer all that and then some.
What Killed 2-Stroke Jet Skis?
2-stroke jet skis are not a thing you see anymore, and the main reason is due to the EPA.
The EPA started cracking down on jet ski pollution, and 2-stroke were the most polluting.
2-strokes are so bad that many of them will leak as much as 1/3 of its gas and oil mixture into the water. That would be about 3 to 4 gallons of gas being dumped into the water on a 2-hour ride.
2-stroke either needed to change or go away, so they were replaced with 4-strokes. 4-stroke don’t burn the oil, use direct injection to cut down on wasted gas and many have different driving modes to help with pollution.
The jet ski manufacturers see the writing on the walls, so the next jump will be to electric jet skis. Sea-Doo has shown us their electric jet ski plan, and I’m certain Yamaha and Kawasaki are testing some themselves. We go a bit into electric jet skis in this post here.
4-stroke Growing Pains
When 4-strokes started appearing, it was a huge shift for the manufacturers and the dealerships. Retooling needed to be done and a quick relearning by everyone.
Many of the very first 4-stroke engines were not that great, a few needed to be rebuilt after a few hours. It’s just the nature of anything new, and with the rush to move to 4-stroke being placed on manufacturers, it’s to be expected.
This brings up the question, when were the “bugs” worked out of the 4-stroke engines?
If I had to give a solid answer it would be after 2006 that we see all manufacturers just get it right. It’s not to say the 2002 to 2006 4-stroke jet skis are bad, but you can tell the few growing pains many of them had.
The biggest growing pain was the superchargers, and that saga didn’t get better until 2012 for some manufacturers.
The golden engines were the non-supercharged PWCs from 2007 and up. The manufacturers still improve their engines, Sea-Doo came out with the ACE engine block in 2016 which was a nice jump and showed what they’ve learned over the years.