Just wondering if it is worth taking the airbox lid off the 400ex, installing a White Brothers Powerflow air filter (my choice over other 3rd party filters), and rejetting with a K&N jetkit? Can I expect a noticeable difference in low end power without changing the exhaust at all?

The goal is to produce a quad that will pull hillclimbs in 2nd gear while NOT being under full throttle. The problem with the stock setup is that 1st gear is too slow (not enough wheel spin) to get up some of the hills encountered and doesn't have enough low-end torque to pull in 2nd gear without being under full throttle. I don't have a problem with it per se because I run the pi$$ out of it up the hill. But it is my girlfriends quad and she does. She is 5'6" and 120 lbs and looses control when under full power in 2nd gear. If she goes too slow then it bogs down but if she really gets into the power zone, it pulls the front end up and she ends up off to the side of the hill.

I tried dropping one tooth on the front sprocket but it still doesn't do the trick. It made 1st even worse for going up the hill and still bogs too much in 2nd gear. She is now back to stock gearing. I am wondering if I go back to the 14 tooth front along with the above mentioned change if this wouldn't be the ticket.

I am prepared to buy a full exhaust or just a slip-on if necessary to solve this dilema but wondered if I could get by without it. She loves her "stealth" bike.

Thanks for any input. Let me know if it is based on experience or just a good educated guess.

 

You'll notice the increase even if you don't get the pipe but you will REALLY notice it if you get the pipe. I'd try putting a larger sprocket on the rear. She should be able to climb hills a lot better. The 400 has tons and tons of low end. She must be encountering some steep hills.

 

take the lid off get for the lid, screw the aftermarket filter (stock one is great) put taht money to a 14 tooth front sprocket, great for hill climbs.