Boost ATV Performance

By nature, ATV riders like power. And it seems that sport ATV riders, especially, always want a little more power from their quads. Here are three ways to boost ATV performance without breaking the bank.

Tune the Fuel System Having the right fuel/air ratio is key to make an ATV run its best. Too much fuel will make the engine feel sluggish and it won’t reach peak RPM. Not enough fuel can cause a burndown, leaving you with a costly repair. For carbureted machines, Dynojet Research jet kits take a lot of the guesswork out of re-jetting an ATV. They include guidelines for temperature and altitude, along with main jets, pilot jets and jet needles to dial in the fuel system. For EFI systems, Dynojet also makes Power Commander fuel control modules. These usually come with a new fuel map already programmed so users can just plug and play, but software is also included so custom maps can be built. Fuel maps should only be programmed by experienced tuners who understand an engine’s fuel requirements.

Give the Engine More Air Air is fuel, and it’s free! Airbox mods can increase air flow to an engine and boost ATV performance. Intake modifications are generally inexpensive and simple, but drawbacks are that the mods can make a quad noisier and more susceptible to a lean burndown; just make sure you recalibrate the fuel system to prevent this. Air filters are a simple way to increase air flow. Foam filters like a Twin Air or Uni use oil to help trap dirt; they must be cleaned and re-oil as part of routine maintenance. K&N filters are made of fabric and are easier to clean because you don’t have to work oil into the element. Instead, K&N filters use a spray on oil.

Adjust the Valves Engines in high-performance sport quads need to be kept in tune to ensure full power and easy starting, and to prevent catastrophic failure. Intake and exhaust valve clearances fall out of specification with use, causing the problems described above. And if valves aren’t kept in check, they can break and damage other parts of the engine, especially if they stretch. Valve clearances are set with shims (a complete shim set costs less than $100). Engines that are run hard and at high RPM require more frequent valve adjustments because the valves suffer more wear. A shop can set valve clearances for you, but with a model-specific service manual, a few basic hand tools and a shim kit, most people with some mechanical experience can set valves in less than two hours.

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