I just bought a 2006 Honda 400ex and was wondering on some good hop ups. Im looking at the new DMC afterburner pipe. I am looking to increase power. I do alot of pit riding i climb lots of HUGE hills and i need the power. Im also looking at a K&N filter and a jet kit. Any suggestions would be great.

Thanks

 

Aftermarket header and muffler, EHS airbox lid, Pro Design adapter and FOAM (UNI) filter. I would never trust my precious motors to a K&N!

Rims and tires????

 

Whats wrong with K&N?

 

K&N, hold one up to the light. You can see right through it. Save if for the street, but event then only with a wrap.

 

ok thanks. I am looking at widening my wheel base, and was wonder if i should just widen the front, or the back also? Which one, and why? Thanks

 

I wont use anything but a K&N on anything even considered to be performance. I do use a prefilter on those rides that will be especially dusty or wet (dont use an airbox cover either).

The foam filters I have tried just dont flow the same amount of air, and are a real pain in the you know what to maintain properly. (try a search for more info because I know that I and others have discussed this at length before)

Anyhoo thats just one of many parts and here is some info.

On a stock engine with a stock bore dont waste your $$$ on a header as it will not produce the gains you need across the rpm range, and can even hurt the bottom end. I have a heavilly modded engine that would benefit from a good aftermarket header, but still run a modded stocker with a silencer in order to increase bottom end torque. I know not everyone agrees with this, but even well known builders like TC have advised against and even built engines that utilize the stocker so save the $$$ for something else.

Unless your wanting to get into the internals of the engine you have already addressed the major areas with just the intake (k&N) and exhaust (new silencer) that will produce the most gains for your $$$, and all the other little stuff like timing advance, rev boxes, amd a host of others are not going to give you the same results, and will only help in small amounts.

Deffinately pick up a few larger main jets, and a larger pilot jet too so that you can dial in the jetting, and allow it to start and idle better with the increased fuel on the pilot.

You can also look into different silencers too since there are lots of options and some effect power delivery. I like most of the disc systems since they allow you to tailor your exhaust outlet size to match your engines power delivery to your riding style. More discs = more flow and better mid to top rpm power, less = more bottom to mid (what really pulls you up those hills).

Now before you start thinking about internal changes like a cam or larger bore or even higher compression get all the safety stuff set up first (nerf bars, skids etc etc) and then tackle the most important thing " the suspension".

With just the basic engine mods your looking to do the machine will be able to go faster than the suspension can handle (the intake and exhaust really make a difference) and you will be faster overall at this point from smoothing the ride and the landings etc than adding more power.

After you get the shocks and other parts dialed in you can always tear into the engine later and pick up the other 20-30% in power that can normally be had with a big bore, high comp, porting, new valves and springs, cam, and other stuff, but know ahead of time very little of it beyond the basics is cheap.

Hope that helps!!

 

+1.25" swingarm will provide more traction and help keep the front end down too. You should get the rear shock revalved unless you are under 120 lbs...then you might be okay leaving it as is.

/Jon

 

I widen all my quads with rims and tires. ITP Holeshot XC's on ITP 9X9" rims in the rear and 10X5" in the front. The tires are wider than stock, and the rims are wider with a greater offset. Makes the quad +3" in back and +2" in front. Wide enough for some increased stability, but not so wide that it can't be trail ridden anymore.

I have wicked hillclimbs around my house. Consider gearing down a bit, say maybe 1-2 tooth larger in back. I don't like longer swingarms, because while it keeps the front down, it actually DECREASES traction because it distributes weight to the front, when you need it in the back for traction.

 

Good point.

Thats another good one, and also one that I had done not long after getting the 400, but as much as it was better over stock (and it was a lot better) the difference between the revalved stocker and a aftermarket rear shock is many times better than the revalve compares to the stocker.

I know not every is wanting or even able to dump a couple or few thousand on suspension, and a revalve on the rear (and even a respring too) plus a good set of works will make words of difference, and not put you back nearly as much in the pocket.

What I can not empathise enough is just how important a properly set up suspension is when it comes to tackling any rough terrain at speed, and the stock fronts just are not up to anything beyond casual riding after just a few decent hard rides (I wouldnt say they are great when new, but are still way better than many others while at the same time not close to any aftermarket shocks). Jumping just speeds up the process so keep that in mind when you start adding preload to make up for the performance of the stock boingers.

 

I have a 400ex and i piped it k&Ned it and it has a jet kit init i put a megamax pipe on it what you should look into is a power bomb header i put one on my 400ex and it gave it some more power about 5% more