New 400EX, help me wake this thing up!

[leasureryan]

Alright, I have this 400ex I just bought, well, practicly stole from a guy at $2500, original owner, so clean you could eat off of it, and aftermarket everything from here to the moon! Only problem is, I am used to my 2 strokes, you know, my light weight little Blaster, that could seriously keep up with the biger 4 strokes. I am used to my powerband and torque, and this 400ex just needs a good kick in the *** to get it moving! It has all of the below, and everything has been done correctly, maybe some slight jetting issues. I want to keep it at stock bore as long as I can, but seriously, I need some go fast info....quick!!! I can barely get this thing to pull the front wheels!


Help me out here....I am a 2 stroke guy! And honestly, I think the wifes 330ex feels like it has more SACK!!!!

[DementeD]

something must be wrong..
it should rape ur 2stroke blaster..and have TONS more tq..
and should easily pull the fronts off the ground..

[BigBore24]

i dont see many engine mods on the list. it wont be super powerful with stock motor but should pull the front up with no problem. id say check your compression first, maybe its a bit sick. also you can stay stock bore and go higher compression that will really help, especially if you throw in a cam also

[Wheelie]

The jettings seems to be pretty close. Install a 11:1 piston and cam, have the head ported as well. The stock bore can be retained, but the power will be upped substantially.

[leasureryan]

I don't think anything is actualy wrong with it, it is just lacking the enthusiasm, kinda like, you know, buying a stock mustang. I mean, this guy has covered EVERY base as far as looks and protection. If you could put a guard there, you bet your *** there is a guard ther. If they make and upgraded version of something fancy, he bought it. He also upgraded the suspension. The only thing to my knowledge that is upgraded performance wise is the FMF slip-on, and the aftermarket air box lid with uni filter.. I know it has been jetted as well, but I don't even know what should be in it with just those upgrades. Said it had a bigger pilot for winter start, and bigger main. Said may run a little rich. It's not that far off if any, I also had a couple guys at the shop take it for a spin, they said it was minor if any. But as I said, this thing just needs some ummph!!!

Don't get me wrong, I can get it to do a wheelie, and I do have to remember that this machine is a TON heavier than my Blaster.

It's got sack, but I want more, without taking it straight to the races right from the get go. If the motor blows up, then, and only then will I bore it, and even then I don't want to go so far that it becomes unreliable.

Help me out here.
What helps?

CDI, Header pipe, 450r carb, cams, etc,etc. Let me know the first step to performance upgrades.

[NickG5755]

you can go 426 and it will still be REALLYYY reliable...

[leasureryan]

all in time my dear friend.......but.....for now????

I am actually thinkingof just buying a whole spare motor, and taking that one as far as I can, this way there is always a spare, in case something crapy does happen, which will eventualy happen anyways

[DementeD]

for now..
most people say a advance timing key really brings the 400ex alive..its like 20-30bucks plus gaskets..
also a new hotcam stage 1 would compliment ur motor pretty well imo..all that should run u under 200 and should feel like another quad..

[supraloud84]

A port and polish will really wake that thing up too. the guys I ride with all ahve 400s and we all have differnt levels of mods. My buddies with a pipe and the port and polish destroys my other friends stock motored machine.

[chayes627]

go for the high compression piston like 11:1 and a stage 1 or 2 hotcam. it will react to that very well

[mitchamus]

what tooth sprockets are you running?
what size tires. also HD rear tires are heavy as hell you could got to a lighter rear tire to get rid of some unsprung weight.
Also remove you choke that will give you a little better throttle response.

[redrider57]

Get rid of that FMF pipe and go with a full pipe. I recommend HMF, but that is just what I run. Drop a tooth up front. Rev box if you don't want to tear into the engine. Sounds like you removed the air box lid, so jet accordingly. If you want to go into the engine, put a Weisco high comp piston, hot cams.

Do any number of these things and it will come close to ripping your arms off, and walk all over your Blaster.

[leasureryan]

yeah...I don't want to pull the choke off.

Probly going to get a Rick's Hot shot CDI, Stage 2 cam, and a full exhaust system, either white bro's or HMF. I don't really like the FMF power core IV, sounds kinda wussy, and I know it doesn't do much for performance, but I will end up keeping it for times when I need a spark arrestor.

What will I have to change the jetting to when adding the CDI, Stage 2 Hot Cam, HMF full exhaust(or equivilant) ????

Not putting a piston in until I need to.

[leasureryan]

also changed from 15 to 14 tooth front sprocket. Will put it on after it comes in. I love working a a powersports shop!!! The discounts are great, and access is awesome!

HMF or Curtis Sparks full system, hot cam stage 1 or 2, bump up the compression to 10:1 - 11:1. that should make a huge difference

[leasureryan]

Alright, well, gonna start by getting this HMF full exhaust from a guy that posted it on our bulitin board at work.

So....HMF it is! $260 in great shape. Good Deal???

But, how much am I going to have to change my jetting going from the Powercore 4 w/stock head pipe to the HMF full system???

Best part is, he has a spark arrestor to go with the HMF, so I can sell the powercore 4. How much you guys think it is worth?? With stock head pipe???

[leasureryan]

This is what some who are selling HMF's are saying is recomended as far as jetting. Sound right to you? If so, I am going to have to re-jet, which was inevidable. Just wanting to know if this sounds right toy you?????????????????

Recommended Jetting Specs: 400EX '99 - '03 Slip on 165/170 Keihin Hex 400EX '99 - '03 Full 180/200 Keihin Hex 400EX '04-> Full / Slip on 152 Keihin Hex / 42 Pilot [B]

[MOON]

165 main sounds kinda high for a stock motor.

http://www.exriders.com/vbb/showthread.php?s=&threadid=344906&highlight=400ex+jetting+and+carb+tuning

in that thread we posted our mods, elevation, riding temperature and what jetting we used for it.

[leasureryan]

actualy....with the full system...they are saying it requires a ....


400EX '99 - '03 Full 180/200 Keihin Hex


I thought that was a pretty dramatic increase myself. But hey, who knows. Like I said, I am a 2 stroke guy. I need tought this 4 stroke stuff!

[Cool Guy07400EX]

I'd say go with the full system, the cam, and CDI but I also recommend getting the Curtis Sparks advance timing key. It really helps.
Also maybe get a 450R carb or if you have the money then throw an FCR carb on there. It's like $500 though but probably the best carb you can get for the 400. :blah:

Hope that helped!!

[leasureryan]

here is what I just bought

thats nice!

[leasureryan]

this FMF pipe has got to go!

[leasureryan]

front view

[sc400ex_rider]

get the hotcam stg 2, 11.1 piston, 450r carb,cut flywheel and the sparks keyway. check my sig this thing rips. the lightweight flywheel makes is feel 2 "strokish" LOL... i only have about $700 in the motor and it winds up pretty fast. the springs and timing chain are insurance. i dont have a rev box also for insurance i only tag it when i miss a gear. i have stock gearing and stock bore 85MM piston for lightweight. the 440 piston weighs 2 oz or 60 grams more. so they tend to rev out a little slower plus if you raise the rpm (rev box) you can stretch the rod. im not saying i have the fastest quad on the planet and im sure there is someone with 4 g's in his 440 that will spank me but for the mony i spent i LOVE this motor. PM for more details

P.S. thats a sweet quad with lots of goodies but some of it is added weight

[krt400ex]

Originally posted by leasureryan
I don't think anything is actualy wrong with it, it is just lacking the enthusiasm, kinda like, you know, buying a stock mustang. I mean, this guy has covered EVERY base as far as looks and protection. If you could put a guard there, you bet your *** there is a guard ther. If they make and upgraded version of something fancy, he bought it. He also upgraded the suspension. The only thing to my knowledge that is upgraded performance wise is the FMF slip-on, and the aftermarket air box lid with uni filter.. I know it has been jetted as well, but I don't even know what should be in it with just those upgrades. Said it had a bigger pilot for winter start, and bigger main. Said may run a little rich. It's not that far off if any, I also had a couple guys at the shop take it for a spin, they said it was minor if any. But as I said, this thing just needs some ummph!!!

Don't get me wrong, I can get it to do a wheelie, and I do have to remember that this machine is a TON heavier than my Blaster.

It's got sack, but I want more, without taking it straight to the races right from the get go. If the motor blows up, then, and only then will I bore it, and even then I don't want to go so far that it becomes unreliable.

Help me out here.
What helps?

CDI, Header pipe, 450r carb, cams, etc,etc. Let me know the first step to performance upgrades.

first thing, i dont like fmf exhaust for four strokes. i love my yosh full system. woke the bike up alot. id say that something isnt right if you are having probs with wheelies...it should come up pretty easy in third without clutch. mine did when it was totally stock. i can do 4th gear wheelies with a little clutch very easily. i raced a modded blaster with my 400 when it was stock and i raped him 300 ft.

do a compression check. baseline for jetting should be something like a 42 pilot, 152 or 155 main, fuel screw about 2.5 turns out. that will get you close. these #'s are with the OEM brand jets.

if comp is low, that is your problem because the 400ex is very crisp off the bottom. throw a better exhaust on there, a mild cam(hotcam stage 1 or 2), and maybe a higher comp piston and the bike will run much better. another thing to check for is the gearing...he may have changed it. mine is an '05 and it is a 14 tooth front and 39 tooth rear stock. if he has it geared taller with stock engine that baby will struggle through the gears. trust me, i tried taller gearing.

Good luck

[krt400ex]

BTW, the #s i gave you for jetting is with a pipe. the stock jetting is a 38 pilot, and 148 main

[krt400ex]

Originally posted by leasureryan
actualy....with the full system...they are saying it requires a ....


400EX '99 - '03 Full 180/200 Keihin Hex


I thought that was a pretty dramatic increase myself. But hey, who knows. Like I said, I am a 2 stroke guy. I need tought this 4 stroke stuff!

180-200 is waaay too rich. the 400ex isnt like the 450s when it comes to a stock pipe. the 450s are super corked up, so the increase in jetting is very dramatic...the 400ex pipe is actually pretty good stock. 155 should do it. that is what i am running in mine, and she runs very well