During its 17-year production run from 1987 to 2004, the Yamaha Warrior 350 was one of the most popular ATVs in the industry.
Even after it was discontinued for the Raptor 350, folks couldn’t get enough of the Warrior.
While its versatility contributed to its appeal among outdoor enthusiasts, so too did the fact that it was one of the fastest ATVS in its class.
Even all these years later, the Warrior 350 still holds its own speedwise with many of the fastest 350cc models.
And just how fast can the Yamaha Warrior 350 go? This guide will answer the following:
- Warrior 350 top speed in stock condition
- Warrior 350 top speed with modifications
- Five modifications that will maximize the Warrior’s top-end speed
Warrior 350 Top Speed
Powered by a 348cc single-cylinder engine with 19 horsepower, the Warrior 350 top speed is 63 mph for those units in fully stock condition.
But for fully modified models, the Warrior 350 can reach a top speed of 75+ mph.
To achieve a top speed closer to 75 mph and keep pace with some of the sportier ATV models, there are a number of modifications that owners can make to their Warrior.
Modifications To Make The Warrior 350 Faster
While there are several mods that will improve the horsepower of the Warrior 350 and translate to more top-end speed, there are also a couple that will increase the top speed without improving the engine output.
- Upgrade the airbox and air filter
- Upgrade the exhaust
- Re-jet the carburetor
- Adjust the gearing
- Add larger diameter tires
Upgrade The Airbox & Air Filter
The Yamaha Warrior 350 loves it some airflow, and the air intake system is responsible for providing the engine with the large amount of air it needs to breathe and run properly.
The more air in and out, the more power the engine can generate. So the goal of an upgraded intake is to increase the amount of clean air that can flow into the engine.
To do this owners will want to replace or modify the stock airbox or airbox cover to enable more airflow, and replace the stock air filter with a high flow filter.
Many owners will simply remove the cover from the stock airbox and ride that way. If doing this, be sure to reinstall it if doing any water riding or washing your quad so the air filter stays dry.
Both K&N filters and UNI filters are highly recommended for the Warrior 350.
Expected increase in HP: 1-3 horsepower
Expected increase in speed: 2-3 mph
Upgrade The Exhaust
You’ve accounted for more air in with the intake upgrade, but you’ll need to account for sending more air out as a result.
Upgrading the exhaust system will accomplish this and provide more torque and horsepower to the engine, resulting in more top-end speed.
It will also provide your Warrior 350 with a deeper growl when riding, making it sound better to most folks.
The highest recommended aftermarket exhaust upgrades for the Warrior 350 are:
- Yoshimura Exhaust
- HMF Exhaust
- Empire Exhaust
- White Brothers Exhaust
- Monster Exhaust
While they’ll all increase performance by around the same amount, they all differ in style and sound.
Expected increase in HP: 1-3 horsepower
Expected increase in speed: 2-3 mph
Re-Jet The Carburetor
Since you’ll be making a change to the airflow by upgrading the intake and exhaust, you’ll need to ensure that you increase the fuel flow as well so that the air to fuel ratio remains optimal.
If not, you’ll run into issues such as stalling and bogging down, and can potentially damage your engine over time.
There are three jets within the main carburetor, two of which will need to be replaced and one that will need to be adjusted to ensure the proper air to fuel ratio.
To find the ideal combination of these new and adjusted jets, you’ll need to do some testing to determine the best fit specific to the modifications you’ve made.
Main Jet
The main jet in the stock carburetor is a size # 145. It will need to be replaced with a bigger jet.
Moving up to a size 147.5 or 150 main jet will do the trick for most Warriors, but owners should test to ensure they don’t need an even bigger main jet.
Pilot Jet
The pilot jet in the stock carburetor is a size # 42.5, and will need to be replaced with a bigger jet as well.
Most of the time, a move up one size to a size 45 pilot jet is ideal for the Warrior. But owners will want to test this as well and potentially go up one more size if needed.
Needle Jet
The needle jet can simply be adjusted by turning it, and many times doesn’t even need to be. But owners should test this one as well to determine the ideal position.
Expected Increase In HP & Speed: None – you are maximizing the full power and speed potential that already exists through other modifications by re-jetting the carb.
Adjust The Gearing
The easiest way to increase the Warrior’s top speed is to adjust the gearing by swapping out one or both of the front and rear sprockets.
For more speed in vehicles with chain drives, you’ll want to slightly increase the size of the front sprocket and potentially slightly decrease the size of the rear sprocket.
But you’ll need to consider that there’s a tradeoff when doing this, in that you’ll lose some low-end torque which will result in slightly less acceleration.
The Warrior 350’s stock gearing consists of a 13-tooth front sprocket and a 40-tooth rear sprocket.
Moving up to a 14-tooth front sprocket and leaving the 40-tooth rear sprocket in place will likely net you the best gain in speed without sacrificing much in low-end torque.
But for those strictly worried about top-end speed and not acceleration, you could also move to a 15-tooth front sprocket and decrease the rear sprocket size to a 39 or 38-tooth which should result in even more top-end.
Expected Increase in Speed: 3-6 mph
Add Larger Diameter Tires
Like many other Yamaha sport quads, the Warrior 350 comes equipped with 21-inch diameter front tires and 20-inch diameter rear tires.
Moving up a size or two should help in adding some additional top-end speed.
22-inch tires in front and 21-inch tires in back seem to make the ideal upgrade as they’ll provide a few more mph of top-end speed without weighing the ATV down enough to affect its initial take-off speed too much.
Expected Increase In Speed: 3-4 mph
Parting Thoughts
A fully stock Warrior 350 will top out at 63 mph. But by way of some common modifications, owners can hit upwards of 75 mph.
Before heading out, check out the following guides to see how the Warrior 350 compares with other Yamaha sport quads:
