If you bought a Yamaha Grizzly 650 a few years ago, or even a used Grizzly 660 recently, you might just be wondering how you can increase power in the venerable Yamaha Grizzly 660 ATV. If you’re considering a few minor customizations to your Yamaha to make the Grizzly 660 your own, than the engine is a great place to start. In the same way in which you would tune a motorcycle to increase power, the same rules apply to ATV’s. The Yamaha being a carbureted four-stroke single, the Grizzly 660 can be tuned to increase power best in three ways which are inexpensive, and one way which will set you back some bucks. All four ways have drawbacks, either with price, or with trading some facet of the Yamaha Grizzly 660 ‘s performance. For instance, increasing the bore of the engine will net you some serious power gains, but the tradeoff is that you have to pay through the nose for it. The average cost of an 800cc big bore kit for the Yamaha Grizzly 660 is $3400, including installation of the engine when the machining is finished. More inexpensive parts for the Grizzly 660 include intakes, exhausts, and carburetor jet kits. These have a more pronounced power tradeoff, however, swapping your powerband from low to high, whichever the case may be.
The Yamaha Grizzly 660 big bore kit from Hauck Power sports is really more along the lines of having the Yamaha engine machined to increase power. They essentially bore out and re-sleeve your cylinders to give you a larger engine. This machining process takes the Grizzly 660 engine and builds it up as an 800cc. Problems you might run into include weakened parts from the machining process, poor fit and oil leaks in older or high-mileage engines after the disassembly and reassembly, and reduced fuel efficiency due to the engine’s using more fuel to increase power. While this is an option, its prohibitive price may just make it more worth while to purchase an ATV with a larger engine to begin with than the Yamaha Grizzly 660, such as the newer Grizzly 700, or even the Kawasaki Brute Force 750.
More inexpensive are the bolt-on parts from Yamaha and aftermarket manufacturers which increase your power less dramatically. These parts, such as air filters, jet kits, and exhausts all use the principle that more air will increase power. K&N; is one of the biggest companies to make high-flow performance air filters for the Yamaha Grizzly 660 ATV. By allowing the engine to take in more air, it allows the fuel to burn more completely, which will increase power. After this upgrade, you may want to consider the exhaust side, as well, particularly if you’re interested in changing the exhaust note of your ATV. Some exhausts are very loud, and claim to have the best power output, but the truth is that a loud exhaust doesn’t increase power. AC Racing has some slip-on mufflers available in the $400 range that should get you where you want to go without irritating the neighbors too much. The third inexpensive option to increase power in the Yamaha Grizzly 660 is the jet kit. This kit usually consists of a few different sized carburetor jets, a drill bit and instructions. If you choose this route, the use of an exhaust and air filter are practically mandatory, so it should really be the last thing you purchase of the three to increase power.
Increasing power output in your Yamaha Grizzly 660 isn’t impossible; you just have to know where to look for the right parts. Stay clear of knockoff brands and remember your tradeoffs, however, and you can have a seriously fun Yamaha Grizzly 660 that’ll be faster than anything this side of a sport Quad.
