Arctic Cat 120 Engine Parts

• There will be more engine parts listed as I have time to add them.  Thanks for your patience.

• The GEN8 valve spring is the best valve spring available today and 100% ISR legal for both Ice Oval and SnoX racing. These are engineered to barely lose any performance after the first couple heat cycles where they lose about .012" in free length. After that they hardly change at all and many customers use the same valve springs for half to a full season. With the use of rev limiters it's now even more important to have good valve springs so you can get out front quickly because once the rev limiters kick in everyone is running the same speed theoritically.

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Adjustable Main Jets and Pilot Jets

• The adjustable main jet replaces the bolt that holds the bowl onto the carburetor and allows you to adjust the fuel flow. By changing the fuel flow you can fine adjust the engines peak peroformance as tempature and oxygen levels change throughout the day of racing.

• PILOT JETS: We offer several sizes of pilot jets sold individually, and now offer a pilot jet kit. The pilot jet kit comes with #55, #57.5, #60, #62.5 and #65 for just $30.

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KOSO Rev Limiters (ISR LEGAL)

• As of the 2014/15 season, rev-limiters are now required to be used on all stock 120 class races. These KOSO rev-limiters restrict the maximum RPM to 6850 and are the only ISR approved rev-limiter devices.
• This rev-limiter uses a 9 volt battery for power so there is no power required from the snowmobile itself.
• A very simple three wire hook up to install.
• There is a rev-limiter for the 1999 to 2009 Arctic Cat 120 with the Suzuki engine and a different rev-limiter for the 2010 and later Arctic Cat and Yamaha 120 with the Yamaha engine.

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9v Battery Box for Rev Limiter

• The battery box on the rev limiters are notorious for breaking or failing, so don't let yourself be caught ready to race and having to withdraw because you don't have a working rev limiter. These are cheap so be sure to have a couple in your toolbox for emergencies.

Yamaha Engine Performance Kit (ISR LEGAL)

• This kit is an absolute must have to run in any stock class race in order to compete.
• The Yamaha engines were made for longevity, not performance. Therefore, Arctic Cat created a kit that would allow the Yamaha engine to run equal to the Arctic Cat 120 with Suzuki engine and the Polaris 120 in stock classes.
• The kit includes a high performance camshaft, valve springs, carburetor jetting, offset flywheel key, and gaskets.

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KOSO Mini 4 Tach

The Mini4 tachometer uses an LCD screen powered by an inner CR 2032 changeable battery that allows installation on any vehicle. With the small, compact and user‑friendly size, it is perfect for many applications. It also features a backlight, has a RPM display warning and also keeps track of your max RPM.

• *** NEW 2022 ***

• KOSO's mini RPM tach is a surface mountable Tachometer that is accurate to 20,000 rpms and features a resetable maximum RPM recall. This multifunction meter is programable to nine different firing patterns to accomodate two and four-stroke engines.

• This tach is PERFECT for racing as it only has a 0.5 second delay between reading and display. Most mini tachs have up to five second delay.

• This tach retails for $89.95, but is currently being offered by Olson brothers at a discount.

• Measures 33.7mm (1.33 in.) H x 61.5mm (2.42 in.) W x 15.6mm (.61 in.) D

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Carburetor Jetting

• 120s typically come with 47.5 or 50 pilot jet. The pilot jets control how much air is allowed into the carburetor to mix with the fuel, thus creating a fuel to air ratio. In order to allow more fuel into the engine, you need to increase the pilot jet size first. Then you'll be able to increase your main jet size (or if using an adjustable main jet you'll be able to increase fuel flow) to match the fuel to air ratio and thus get more fuel into the cylinder.

• Olson Brothers Dist is working on a new adjustable main jet for 2016/17 season and will post more information in the fall. For right now, we only carry in stock adjustable main jets for the Arctic Cat Suzuki engine.

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Spark Plugs

• Standard and Iridium NGK spark plugs for Kitty Cat and all 120cc sleds. Order on-line or call 651-485-3771.

• Iridium plugs last longer and have more spark surface for better fuel ignition.

• E3 plugs are designed for high performance engines and have a diamond shaped electrode for greater spark.

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