hop up on a 400ex

[Desperado]

ok guys here is my deal. i bought a 400ex from the dealer new in 01. the quad was brand new and it came with a pro circuit t4 pipe, k&n filter and jet kit. they had it as a demo and i bought it cause it had the pipe. it was also geared up 1 tooth on the counter shaft to give more top speed (i did this cause i ride in large open areas) and i also have the airbox lid drilled


so here are my questions

1. would i see a gain from a head pipe install?
2. is the pro circuit t4 pipe any good?
3. how much do you think i picked up over stock with current mods?
4. what would you do to this quad for more drag racing power and trail fun. (no big bore kit or cam)

sorry for the simple questions but i got to know. the new 450 has come out but i can't see upgrading since i don't ride as often as i did due to work. so i want to be faster without going to a big bore kit or cam. so thanks for the help in advance

[JDiablo]

i woudl sell that pipe and invest in a HMF full or sparks full

[Florida400EX]

Originally posted by 300exrida
i woudl sell that pipe and invest in a HMF full or sparks full

Pro Circuit is just as good as either of the ones you've listed, the gain could only be shown on a dyno. Pro Circuit's quality is also one of the best.... For just play riding, don't get the headerpipe, because you will loose quite a bit of low end power, and it will gain better topend. If you're looking for more power, but dont want a big bore, or a cam, then look into a 39MM fcr carb.

[foleyit]

1. You would see some gains from installing a head pipe, but would see much more gains if you sold the T4 and bought a full system.

2. Your current slip-on is not a bad pipe, it's not the best in my opinion either. The WB e-series gives you more flexbility to add/remove discs as needed for your riding needs.

3. I'm sure the mods you have woke it up a little.

4. It really depends on how much you are willing to spend on the 400ex. I'm sure there are some gains from a full like HMF, Curtis Sparks, or WB R4 pro meg system, but not nearly as much if bored it over. Drop-down to a 14t front sprocket -- you will lose top-end for those wide open areas you mentioned, but should get some quicker starts in return. You can probably put in a higher compression piston, and while you have the head off, install a drop-in cam like hotcams (stage 1 cam/trails, stage 2 cam/open areas) or HRC. Depending on your riding/trails terrain investing money into your suspension wouldn't hurt.

[Steve-o 400EX]

If you install a head pipe, you will NOT see any gain, you might even lose some on a stock motor. Most aftermarked head pipes are too large unless u have motor work done. U willl lose bottom end bigtime. YZROOSTINYA would back me on this one. We have done some tests on this theory. U are basically stuck without doing motor work, a 416 is fairly affordable though, think about it, its like 350 for the kit if self installed which is not hard at all. PM me with Q's.