There are two major problems with the stock 120 sleds. One is the motor only turns about 3,000rpm before the stock governor kills the party. The other problem is with the stock gear ratio and the heavy #40 size chain coupled with a 10t stock front sprocket.Our Economy Speed kit fixes both! Governor Spring - Most people know that the stock spring is too weak. And a lot of people think it's okay to bypass the governor with a zip tie or piece of wire. The problem with doing that is if the motor is then run at a constant too-high rpm with no relief on the governor, that little plastic governor gear down in the engine is eventually going to break, scattering parts and doing extensive damage.
The correct way to do it is to put a proper tension spring which will allow a safe 5,000rpm and then open to relieve the governor and also keep the piston from hitting the valves as well. 35 Chain Conversion Kit -Simply put, The stock #40 pitch size chain doesn't work! With the smaller 35 pitch chain we have found that there is far less less rolling resistance than a stock #40 chain and gears have.This is because the rollers are smaller and the sprockets have more teeth on them. This reduced resistance results in better performance along with reduced chain wear and noise. This easy to install kit will set you up right. Includes a new #35 clutch drum to swap out with your stock unit, a quick change rear hub, aluminum sprocket and a #35 chain. The clutch engagement rpm will be the same as stock, but the new revised taller gear ratio will deliver several more mph than stock on top end. Try it today and more than double the stock 7mph speed of that little sled! Typical speeds achieved are 16-18 mph depending on snow conditions and rider weight. The item "Arctic Cat 120 Speed Hop Up Gearing Kit Z120 ZR120 SNO PRO 120 2000-2009 ON SALE" is in sale since Monday, February 17, 2020. This item is in the category "eBay Motors\Parts & Accessories\Snowmobile Parts\Accessories".
The seller is "midwest-mini" and is located in Cape Coral, Florida. This item can be shipped worldwide.