Hi everyone..I recently bought a 2003 400ex and I was wonderin what aftermarket parts I should get and witch ones to get first. Thanks for the help

 

Your going to need a good pipe, just a slip-on because the Honda header is pretty good. Unless you have money to waste a complete system.

Just take a dremel and grind out the welds on the inside of your header. That will help exhaust flow.

Then you can buy a K&N or any other high-flow filter and possibly modify your airbox for better airflow.

You can take it a step further with new cams. Most people use Hotcams, Stage 1 if your not going to go insane on the engine mods. Stage 2 if your going all out.

In the future you might consider boring your cylinder to a 416ex and adding a higher compression piston to add some torque.

Then you will need to re-jet that carb.

Good luck
Have fun

Jeff

 

Protect your investment(?) first. Get a full frame skidplate. Unless you are super serious about weight, get the Pro-Tec swingarm skidplate if you ride near rocks, etc. All others just get mangled. To be honest, I've found a-arm skids on a 400ex to be optional - the frame is wider thus the a-arms aren't as long as some other quads. New lower a-arms are relatively cheap too.

Nerf bars are key for protecting yourself so you can ride. I don't know anyone who has run over his/her foot with nerfs but I know several who have without them. Many like the new, almost all aluminum A/C Propegs - they look great and are lightweight. I hate them because I don't like the height on even the stock footpegs and these are about 1/4" higher than stock. You can still get the old DG style Propegs that lower the footpeg height 1" and moves it back 1". They are under the name Magnum now. You can get them from www.dirt-deals.com. Although heavier, the footpegs are solid steel and much wider than stock. The balance on the bike is much better and you can wheelie at speed over obstacles much easier. Obviously the higher your footpegs the harder is is to pull the front end up.

If you want to save your front shocks, take them off and grease the lower bushing especially.

Power upgrades:

Phase 1 - open your airbox lid, get a replacement air filter, and rejet the carb and gain maybe 2 ponies.

Phase 2 - add an exhaust and rejet again for more power.

Phase 3 - internal changes to the engine.

Change to a 14 front sprocket and a 39 rear unless you are into top speed. If you ride in the trails where you rarely can get to 5th gear anyhow then this is a good setup.

Get rid of the rear emergency brake setup. Get a Cascade blockoff from Rocky Mountain ATV. It is less than $10 and comes with two hex screws that are recessed within the blockoff and it comes with a rubber ring seal. It looks much nicer than the ones that expect you to use the stock bolts.

I highly recommend one of the perches and clutch levers that advertise a 30% reduction in pull.

Get rid of the stock handlebars. Enjoy life and install a set of heated grip warmers from Rocky Mountain ($19.00) at the same time. These will install under any rubber grips. You would be surprised how much longer and better you can ride when your hands are truly warm. Trust me, I've ridden plenty of times with wet gloves in the winter mountains. These allow you to keep riding fast while others just can't hang on anymore.

/Jon

 

Thanks for you input.

 

Get a kill switch. Pro Design makes a good one for about $35-$40 bucks and there easy to hook up.