To the greatest delight of fans, 4-stroke Polaris snowmobiles have made a comeback for the 2023 model year!
If you want to find out all about these sleds as well as the all-new ProStar S4 engine, this post is for you.
We at PowerSportsGuide have compiled all you need to know under one roof!
Did Polaris Ever Make a 4-Stroke Snowmobile?
Yes, it’s a lesser-known fact that Polaris manufactured many different 4-stroke snowmobiles in the early-2000s. Some of the most popular vintage Polaris snowmobiles were as follows:
- 2004 Polaris Frontier Classic 700
- 2006 Polaris Classic FS IQ Touring 750
- 2006 Polaris Classic FST 750
- 2007 Polaris FST IQ LX 750
- 2009 Polaris FST Switchback 750
- Polaris Indy 120
The first 4-stroke Polaris snowmobile was the 2004 Polaris Frontier Classic 700. Contrary to its name, this model utilized a 4-stroke, 784cc engine rated at 48 HP.
This liquid-cooled twin was influenced by Polaris ATV engines, but it came with some advanced features like an electronic fuel injection (EFI).
In the follwing years, the 4-stroke Polaris snowmobile fleet was expanded with some new models, which were marketed with two engine options.
The new 4-stroke Polaris 750 snowmobile engine was available in a naturally-aspirated, 80 HP configuration in the Polaris Classic FS IQ Touring.
Other models included the Classic FST 750, FST IQ LX 750, and the FST Switchback 750, which enjoyed the more powerful turbocharged, 4-stroke, 750cc twin rated at 140 HP.
According to Supertraxmag, these sleds never become popular, so they were eliminated after a few years of production.
Besides these big boys, Polaris has been offering its tiny 120cc sled for a long time. However, this sled has been marketed under various names like 120 Youth, Assault, and Indy.
This machine is one of the smallest production snowmobiles engineered for the youngest riders.
The Indy 120 also uses 4-stroke technology, as it’s powered by a free-air 121cc, 4-stroke single engine.
This sled is still part of the latest Polaris lineup, just like the all-new Polaris 1000cc 4-stroke models!
Yes, you read correctly, after a break of 10 years, Polaris decided to re-enter the 4-stroke snowmobile market with some nice big-bore sleds.
Would you like to find out more about these innovative sleds?
Keep reading!
Does Polaris Make 4-Stroke Snowmobiles Right Now?
As reported by SledMagazine.com, 4-stroke Polaris snowmobiles have returned for the 2023 model year, powered by the all-new, innovative ProStar S4 twin engine.
This means 4-stroke Polaris snowmobiles will hit dealerships in late 2022!
Which Polaris Snowmobiles are 4-Stroke?
The new 4-stroke Polaris snowmobile models for 2023 will be as follows:
- Polaris Indy XC 129/137
- Polaris Indy Adventure 137
- Polaris Indy Adventure X2 137
- Polaris Voyageur 146
- Polaris Titan Adventure 155
- Nordic 146 (European model)
Let’s drill into the details and take a closer look at the new 4-stroke ProStar S4 engine!
Polaris ProStar S4 Engine Review
What is the ProStar S4 Engine?
The ProStar S4 is a new 4-stroke Polaris snowmobile engine introduced for the 2023 season. This liquid-cooled, 998cc twin power source was derived from the proven Polaris ProStar engine used in the off-road RZR 1000.
However, the engine saw some major updates to be reborn as a purpose-built snowmobile engine. These upgrades include material differences along with some key improvements for increased power and reliability.
For example, the ProStar S4 comes with a dry sump crankcase, which ensures proper lubrication even on the hardest terrain. This design also helps to lower the engine’s center of gravity, which is always welcomed on a sled.
In contrast, the original RZR 1000 engine has a wet sump design.
Other improvements include a tweaked 270/90-degree firing order, which ensures more torque and a “Haley-like” exhaust sound.
The ProStar S4 utilizes 4 valves per cylinder that are controlled by double overhead camshafts (DOHC). To minimize vibration, the engine has a well-designed gear-driven counterbalance, which ensures a smooth operation.
The P22 clutch is fitted on the PTO side of the crankshaft. This design was borrowed from the turbocharged Patriot Boost engine.
The clutch also features an idler bearing on the primary post, which ensures easy starts and a longer belt life.
What’s more, the ProStar S4 comes with an advanced throttle-by-wire system, which allows you to choose among a variety of riding modes including “Sport” or “Standard.”
Keeping safety in mind, the system features a throttle-override function intended to cut off the throttle if you accidentally leave your fingers on the brake lever for too long. The main idea behind this feature is to save you from brake overheating issues.
How Much HP does a ProStar S4 Engine Have?
Although the official numbers haven’t been released, according to Supertraxmag, you can expect the power of the ProStar S4 engine to be around 90 HP.
Polaris ProStar S4 Specs Chart
For your convenience, we’ve compiled the key specifications of the ProStar S4 engine into one chart:
| Specs | ProStar S4 |
| Displacement | 998 cc |
| Engine stroke | 4-stroke |
| Cylinders | 2 |
| Apsiration | Naturally aspirated |
| Bore | 93 mm |
| Stroke | 73.5 mm |
| Fuel System | Sequential Port Injection |
| Ignition | Spark, Coil On Plug |
| Starting | Electric |
| Exhaust | Single |
| Cooling | Liquid |
Disclaimer: This chart is for informational purposes only! For exact specifications, refer to the factory manual.
Takeaways
After a decade-long break, 4-stroke Polaris snowmobiles are being re-entered for the 2023 season.
These amazing sleds borrow their chassis from their 2-stroke siblings but utilize the all-new ProStar S4 engine.
This 998cc, 4-stroke twin is based on the ProStar engine of the RZR 1000 off-road vehicle, but it was improved in many ways to make it “sled-compatible.”
These upgrades ensure more engine power, a lower center of gravity, and increased durability and efficiency.
The estimated engine power of the ProStar S4 is about 90ish HP, while the fly-by-wire throttle system and the smooth P22 clutch provide effortless handling.
Polaris offers this new power source in different chassis including the Voyageur, Titan Adventure, and Indy.
We can’t wait to try these new 4-stroke Polaris sleds on the snow!
References:
https://snowmobiles.polaris.com/en-us/snowmobile-engines/prostar-s4-engine/
https://sledmagazine.com/2023-polaris-snowmobiles-2-new-engines/
https://www.supertraxmag.com/features/polaris-prostar-s4:-the-wait-is-over!/n4290
https://snowgoer.com/news/2023-polaris-snowmobiles-a-major-power-play-for-the-trail/30475/
