Improving the Horsepower of the Grizzly 700

Improving the horsepower of your Yamaha Grizzly 700 ATV can be done using any of several options, but your should be aware that you will not be able to gain extremely high horsepower numbers without significant engine work. In general, you should expect to be able to add approximately 15 - 20 horsepower to your ATV and spend slightly less than $1,000 to do it. The parts that you use for the build should be of the best quality you can afford to help prevent issues with ridability of the Grizzly 700. Because much of your time on the Grizzly will be on the trail, usually far from your trailer or garage, it's more important that the engine be as reliable as possible. If not, you could find yourself walking back and having to figure out a way to get your Grizzly unstuck and back home again.

The more modifications you perform on your engine, the greater the liklihood that it will not function correctly later. If your Grizzly 700 is still under warranty, you will not want to perform engine service, as you may find that this will void the warranty. You can still add some bolt-on parts and maintain the warranty, but you will have problems getting warranty service if you install parts such as big-bore kits onto the ATV. This means that the best parts you can select for the work are a free-flowing air filter, high-performance exhaust system, and a fuel injection tuning device. The three of these performance parts will significantly improve the power of your ATV while at the same time maintaining the factory warranty, predominantly because you aren't changing any of the engine's internal components. Both the air filter and the exhaust system are intended to be replaceable, and the fuel injection performance tuner allows you to feed more fuel into the engine to balance the added air and exhaust from the other parts.

Begin by unbolting the muffler from the exhaust system and replacing it with a high-performance muffler. You will find that this is the easiest modification you can perform, because all you have to do is loosen the compression fitting around the mouth of the muffler, unbolt the retaining bar from the chassis, and then replace the muffler with the new replacement muffler.

The next step is to install the high-flow air filter onto the engine. You'll have to remove the engine cover just behind the handlebars to do this, but with the cover removed, you'll see the air box and other components immediately accessible.

Finally, reprogram the engine with the fuel injection kit. These kits install between the engine computer and the engine, fitting into the wiring harness and allowing you to adjust the power of your Grizzly 700 by indicating how much fuel is added to the air/fuel ratio. After you have installed a high-flow air filter, you should tune the Grizzly so that its fuel mixture is slightly richer. You'll want to retain the correct air/fuel ratio in balance or the ATV won't run quite right, and you may actually lose power rather than gain it.