What gains should I expect?

[rcatvrider]

I finally am getting some performance mods for my 400ex and am wondering what kind of gains I will be getting. I'm pretty happy with it's current performance, but more power is never a bad thing. I'm riding with a 450 and a modded z400 so it would help. Here's a list of mods I will be doing all at once-
Already ground the header welds
Jardine slip on
uni filter, no cage
homemade ehs style airbox lid
timing advance key
removing the choke
adjusting valves(just maintenance, hasn't been done before)
rejetting with a 42 pilot and somewhere around a 155 main, maybe shim the needle up a little
Debating removing the snorkel

What type of gains should I expect and where in the powerband? Hoping some people have done these mods at once or have ridden stock and modified ones so they can tell me the difference.

Definitely shim the needle. Im running the 3 mods in my sig with the airbox lid on and stock snorkel with a 155 and 42 and it still pops in mid-range. I need to shim my needle.

[Honda10]

this might be a stupid question but how do you shim the needle?
Cuz I just put an HMF slip-on K&N and no airbox lid and have an 05. And need to know if I need to change the needle position.

[Brauap]

The cage on the UNI is made so when it is sucking in mass quanties of air, it doesn't colapse.. wtf did you remove it?

(Removing snorkle only makes it easier to remove the air box.. no preformance.. if so.. maybe .000001 hp!

All your 'mods' are so very little,

Originally posted by Honda10
this might be a stupid question but how do you shim the needle?
Cuz I just put an HMF slip-on K&N and no airbox lid and have an 05. And need to know if I need to change the needle position.

Tiny washers under the non adjustable clip

[powermadd400ex]

Originally posted by Brauap


All your 'mods' are so very little,

please, dont comment if you do not have any idea what you are talking about.
anyways i am interested in this as well considering my engine is stock.

My pipe woke my 400ex up way more then I thought it would. It pulls so much harder then I thought it would.

Between my pipe, filter, and sparks key, it made the 400ex a completely different animal. My dad and friends who rode it said the same thing.

The thing has some snot now.

rcatv, you should also look into the sparks key. It's $20 with the puller. I didn't believe all the hype people made it out to be, because most of the time they're just talking bs.
But when i installed it there was a huge noticeable difference in mid-top end.

i dont know about jardine for quads i only know them for bikes. But the mods list looks good, similar to mine and i'm rapin 400ex with a pipe and air filter.

[Brauap]

Originally posted by FoxHondaRider
please, dont comment if you do not have any idea what you are talking about. anyways i am interested in this as well considering my engine is stock.


Sorry, I didn't finish my post.. :eek: haha

, in HP..


because you most lickly very little, if any premormance between the pipe grounds, choke removed, no cage vs cage on your UNI, and the air box lid mod (tho it sounds alot better w/o a let IMHO.)

anyone else see something weird? lol

[rcatvrider]

Originally posted by Brauap
The cage on the UNI is made so when it is sucking in mass quanties of air, it doesn't colapse.. wtf did you remove it?

(Removing snorkle only makes it easier to remove the air box.. no preformance.. if so.. maybe .000001 hp!

All your 'mods' are so very little,
There are tons of people running it without the cage and I'm pretty sure hornet god is one of them. No one who has actually done the mod complains, everyone who runs without the cage says it has worked fine for years.

As far as removing the snorkel, if anything I would say it reduces performance by removing another opening for air to enter. I just mentioned it to state all of my mods. It cleans it up a bit. I'm going to experiment with and without the snorkel and if it makes no noticable reduction in performance I may block it. I will probably end up modifying it so it introduces more air though.

[rcatvrider]

Originally posted by Brauap
Sorry, I didn't finish my post.. :eek: haha

, in HP..


because you most lickly very little, if any premormance between the pipe grounds, choke removed, no cage vs cage on your UNI, and the air box lid mod (tho it sounds alot better w/o a let IMHO.)

I remember there was a time when you also ground the header welds and removed the choke. It's free, so why not do it? Everything helps. And removing the lid is common sense. It provides much greater area for air to go into the airbox. There are dyno charts proving that it makes an increase of 2+ horsepower and that is without rejetting and everything else stock.

[rcatvrider]

Originally posted by FoxHondaRider
i dont know about jardine for quads i only know them for bikes. But the mods list looks good, similar to mine and i'm rapin 400ex with a pipe and air filter.
I have heard alot of good things about the jardines and only a few bad rating from people who don't even own the pipe. dirtrider did a shootout of pipes on a yz450f and the jardine had the most in the seat power and was best on the dyno. I have only found a few people with it on the 400ex, but they all noted it had noticeable increases. For 95 bucks brand new I couldn't pass it up.

In the woods as it is i can keep up with anyone I ride with but on the straight they can pull away so it would be nice to have some more power.

[rcatvrider]

Originally posted by DMC-4OOEX
My pipe woke my 400ex up way more then I thought it would. It pulls so much harder then I thought it would.

Between my pipe, filter, and sparks key, it made the 400ex a completely different animal. My dad and friends who rode it said the same thing.

The thing has some snot now.

rcatv, you should also look into the sparks key. It's $20 with the puller. I didn't believe all the hype people made it out to be, because most of the time they're just talking bs.
But when i installed it there was a huge noticeable difference in mid-top end.
This is what i was hoping to hear. I am getting a timing advance key, just not the sparks one. I'm pretty sure I mentioned it but I'll check just to be sure.

[rcatvrider]

Originally posted by DMC-4OOEX
Definitely shim the needle. Im running the 3 mods in my sig with the airbox lid on and stock snorkel with a 155 and 42 and it still pops in mid-range. I need to shim my needle.
Alright, I have plenty of small washers. I had an adjustable needle on my old quad so I know about how much one clip position is.

Originally posted by rcatvrider
This is what i was hoping to hear. I am getting a timing advance key, just not the sparks one. I'm pretty sure I mentioned it but I'll check just to be sure.

Yeah. I didn't buy the sparks one myself. I got the one off ebay and it's been great so far.

[Honda10]

if I have an hmf Slip-on and k&N with open airbox how much do I need to shim the needle?

[3or4HONDA]

i run with an open airbox and have my snorkel plugged. I did it because without haveing the lid the bike can suck as much air as it would ever need, so i removed the snorkel and pluged the hole so that mud, water, and other debris would get in the airbox. Also running down dusty trails you may get a little cleaner air from under the seat then through the snorkel up front.

this is just my reasoning for it, as for performance i def did lose any but couldnt say if i gained any or not.


also would the sparks key be alright with a 416 11:1?, i just dont want to much heat

[Brauap]

You will be alright with the key...

but now with the dirty air thing.. its better to run the snorkle in dirty conditions because it is hid from all the other dirt in the air, because it is under the seat, under the gas tank, and above the engine and heat guard.. its pretty clean! And if you run an outerwares on the snorkle (they make them for it) its even better! But its fine, just don't be running any K&N with that open lid, and make sure your filter is always oiled and cleaned!!

[rcatvrider]

I'm going to be running a lid similar to ehs which probably has a small amount of restriction compared to no lid at all so I'm thinking of keeping the snorkel.