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Dyno Jet Kit For 2004-2005 Yamaha Yfz450 (Stage 1&2) Q421

$69.99  $62.99
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Take your performance to new heights with a Jet Kit for your ATV. Increase power and improve performance throughout the entire RPM range, while improving throttle response and smoothness. These Jet Kits take the guesswork out of tuning your ATV.

Whether you’re rolling with a stock ATV or you’ve made some modifications, our Jet Kit will optimize your air/fuel ratio to eliminate rough spots and help you take control of your ATV’s power. You can go with a Stage 1 Jet Kit to give your stock engine a 5% boost of horsepower or send it all the way up to Stage 3 if you’ve already made major modifications to your ATV.

Perfect for ATVs with a stock engine using the stock airbox, air filter, and pipes. Stage 1 Jet Kits are engineered to improve throttle response and deliver approximately 5% more horsepower than stock. These kits are fully adjustable to allow the use of well-designed aftermarket pipes and stock replacement air filters, like K&N.

If you’ve made slight modifications to your ATV, but still crave more performance, a Stage 2 Jet Kit is the solution. With a Stage 2 Jet Kit, you could see power gains of approximately 8%. This kit is intended for ATVs with stock or mildly tuned engines using a well - designed aftermarket pipe with a modified airbox and a stock replacement air filter.


  • 5-8% power range
  • Fully adjustable
  • Increases power and drivability
  • For carbureted vehicles only

Dynojet’s jet kits are designed to upgrade every part of your carburetors air/fuel ratio with included step-by-step instructions for whatever you need upgraded. From your fuel needle to the main air jet, Dynojet has extensively tested every component, which means that you’ll see results as soon as you rev the engine.

These jet kits give some extreme upgrades in a small package. They increase power and smoothness throughout the entire rev range while maintaining fuel economy. There are multiple kit options from stock commuter motorcycles to race-ready bikes and everything in between.


  • YAMAHA YFZ450 2004, 2005
  • Model: Q421
  • Manufactured by: Dyno Jet

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