Little cheap mods do make a difference

[OregonEXrider]

I got my 04 400ex and I took the baffle/restirictor/spark arrestor off. Cost free. Then I took the air box lid off and put a white bros air filter on. Cost 23.50. Then I bought a 158 main jet and a 162 main. Cost like $7.00. Left the air box lid off.

For a total of less then 31.00 I am very pleased with my power gains. Before when I'd go out and have little play racers or what ever with my friends I would almost always loose. I am pretty heavy. They are all piped, and have paddles. Now even with alot of weight difference I can normally tie them and if they are near the same weight as me I smoke them!

Just wanted to put that up there for guys like me who can barely afford the quad much less a couple hundred or better in mods.:D

[daimon1054]

I saw a dyno run with the baffel and arestor in and out and it lost power with it out. The gains you are getting are from the box lid and jetting. The stock muffler was not made to be run open.

[OregonEXrider]

Originally posted by daimon1054
I saw a dyno run with the baffel and arestor in and out and it lost power with it out. The gains you are getting are from the box lid and jetting. The stock muffler was not made to be run open.

I dont trust dyno's......I hear the same thing on 4x4 boards you hear oh I put this part on and it lost power on the dyno, or I saw this or that on a dyno. There is no way you are going to loose top end power with a straighter flowing exaust. What do you think a pipe does? They are flowing straight through and hitting the discs at the end. All those discs do is tune the sound. FWIW the stock chrome peice was left bolted in it was just the deal in the middle that was removed. No offense but I will trust my first hand expereince before a dyno.

In thinking about it though I could see a loss in power if it was not rejetted. That could cause it to run a little lean.

[daimon1054]

If you run on 10 dyno's you will get 10 different #'s but if you run on the same dyno the same day you can compair results. The thing to remember is the #'s them selves mean nothing.

When you run on a dyno you also attach an exhaust sniffer and it tells you what your air/fuel ratio is at all RPM's and on the test that I am quoting the jetting was spot on.

Honda spent a lot of time making sure the back pressure was right and that the stock system made the max HP per noise it could. When you pull the guys you loose back pressure that the motor needs to produce torque. By pulling the stock system you end up with something like the old Cobra exhaust, it made a lot of noise and had 1 more HP or so on top but you lost power every where else on the curve. I promis this to you, you are not making the power you could be with the guts pulled out, yes you might be making more peak power but you do not ride at 1 RPM you ride along the entire RPM range and loosing power from bottom to just a few RPM from top is not the E-ticket.

I am not trying to lead you off I am trying to help you out but you do not need to take it if you wish. When you get the money just add a slip on system. The stock head pipe has a ring in the flange which acts like a torque stuffer (adds back pressure and increases torque) and will make better power down low where you need it, when you go larger with the motor then toss the stock head pipe because it does cost HP on top but your stock motor does not like to rev even if you were to swap the CDI so there is not need to chase RPM's.

Last never trust the butt dyno it does not work, you will swear you are making more power but just be making more noise.

[stonerider250x]

the discs on and exsaust do not only tune sound they also tune performance. guttin ur stock pipe is just like goin and geetin a paice of pipe and stickin it on ur header. u lose power. trust me ive put a straight pipe on mine just playin around:devil: :devil:

[OregonEXrider]

well like I said seat of the pants improvement throught the rpm range. The butt dyno has never failed me, and it is proven when I race and hill climb etc...When do you need the most HP when your riding along at your own pace or when your racing and hill climbing? Your jetting should change with almost every mod you do. When you go from a 1" exaust exit point to a 2" your jetting is going to need to be changed. I am not telling anyone this to make them do this mod or say dont get a slip on. For comparison purposes when I was stock my friend with only a slip on FMF pipe would beat me in every race no matter what. I did this mod and it actually preformed better on the low end but it actually didnt pull that great threw very top of 3rd until we jetted it. Now I can not only keep up with him but I can normally win. Just putting the info out there to help someone as broke as me.....:confused:

[flyingbyfast400]

DYNOS Cost money to use........... or around me they do anyways....
Sumthing alot of us dont have alot of....

[smith_400ex_213]

i hear ur supposed to runn slicks for tires when u dyno ur quad to get and a more accurate reading

[ill_lil_romey]

Before I PAY to use somebody elses dyno, which may not even be calibrated properly, I'de rather use my dyno. TRACK TIME manoAmano:eek:

[TheJeSter1340]

Originally posted by smith_400ex_213
i hear ur supposed to runn slicks for tires when u dyno ur quad to get and a more accurate reading

Yes, you do lose HP with knobby tires. The Dyno will also tear up knobby tires. But are you going to run slicks on a track? Knowing how much actual HP your bike puts out is great, but how much is it putting to the ground?

With that said. I am putting out 42 hp with slicks, probably about 37-38 with knobbies.

[Cody_300ex]

Hey another thing you could do is grind the welds off the header, it made a lil bit of differnice on my 300!