Sep 2, 2001
Hey Guys, new contributor to the forum, but long-time reader. I just bought an almost brand new DRZ400e so I have something to ride with my son. My father (67 year old enduro riding stud!) has a DRZ400e and I have enjoyed trying it out. The only thing I'd like to get is just a little bit more low end, but I don't want to change pipes if it increases loudness. I've read some miscellaneous posts about increasing the breathing through either drilling or removing the airbox cover. Anybody have any experience on how this impacts the power/torque? Is it better to drill or remove? Does the carb require any adjustments? Any other ideas to improve performance without radical surgery? Thanks in advance for the help!


Welcome, Kudzu!

Former DRZ owner here. Two things that you can do to wake this sleeping giant that will only cost you about $3!!
1) The air box is under the seat and it has a flexible, rubber lid on it. Just yank her off!!
2) Once you open the airbox, you will need to replace the main jet. I forgot what size came stock but I believe it was a 145 (or close to it). Replace that with a 158 or 160.

You will be amazed at what these two little mods will do for that bike! Couple of tips on replacing that main jet: It is difficult, at best, to get to. But it is do-able! Do this from the left side of the bike. There is a cap on the bowl on the bottom of the carb about 1/2" above the starter. Take this cap off (that's the easy part!) and the very bottom tip of the main jet will be exposed. Loosen the two clamps around the carb so you can rotate the bottom of the carb towards you. Here, you will have to get creative and get ahold of that sucker some how and unscrew it. It is a 6mm hex shape. Then, just reverse the process to install the larger jet.

There are also now several quiet pipes on the market that people seemed to be pleased with if it comes time for you to get a pipe. For a wealth of DRZ information, also check out www.thumpertalk.com You will see a lot of familiar faces there! Post here or Email me if you have any other questions or concerns. Good luck!:)

Skid Jackson

Nov 1, 2000
I have a drz e that hasn't been broken in yet so i don't qualify as all knowing, but..... I just put a 13 tooth sprocket on mine and while i only had a chance to ride it around the parking lot I'm thinking i'm gonna love it in the woods. All i do is trail ride so i don't need a "race" set up. I'd say start with the sprocket, see what you think, then go from there. Just my .02


May 17, 2000
Not, only change the main, but also lower the clip position one notch on the
needle and turn the fuel screw out to 2 turns when you get ride of the airbox lid, this will richen it up and wake up the low-end, I would also drill out the
exhaust end cap using a 1-3/8 bi-metal hole saw. it lets her rev a bit more
and keeps the bike running a little cooler, it doesn't add alot of noise at all
unless you start drilling through the inner baffles. Its a great bike. Borsy
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