400ex help plz

[icy1155]

I recently got a 400ex and i am looking to increase the horse power. I will soon be getting a new slip on for it, and i was looking at the different 440 big bore kits that are avalible and i was wondering if people could give me some input into wether i should get the 12.5:1 or 11:1 and stage 1 or 2 (for the hotcams). I am also getting a new CDI, i just got in my skid plates and twist throttle, and was wondering if neone had suggestions on other good and reasonably priced modifications for the 400ex. THANKS. :D

[deejayeb]

Whats up bro

First thing - If your gonna get a 440 kit, dont bother with just a slip on, you gotta get a new header so it will breathe better. I just got the new Sparks Big Core which is a little more (550) but it has a 2.5 inch diameter instead of the normal 2". If you can get the 13:5:1 I would go for it! Im rockin 11:1 now on my 440 and I smoke every 400 I line up against. Some other mods you can do it just to lighten up the bike. I moved my battery up front, shaved off all the little brackets the battery used to sit on. Your also gonna need to eliminate your airbox and get a big K&N intake filter if your gonna go 440. (bike has to have plenty of air) - I also put a twist throttle on mine and your gonna love that. other stuff you can do is cut the front and back plastics for less wind resistance, take off Nerf's if you have those. Take off the parking break (about 2 pounds alone!) if you dont use your front breaks ever you can take those off and that about 5-7 more pounds. get a lighter axle for 200 bucks which eliminated about 3 pounds. Just all the little stuff man. The lighter your bike is the faster its gonna go. also if your gonna get a 440 your gonna have to run high performance 4 stroke oil to help keep the engine running cooler, because a cooler running engine means more horsepower. theres a ton of stuff you can do man. If you have anyquestions about anything just ask. ive done all my own work so I can answer most of the questions you'll have. Heres a pic of my bike after moving the battery and taking off a bunch of stuff.

later

[icy1155]

Thanks. I already have the fenders cut :D and the parking break off, and i was thinkin about getting a different airbox that moves the battery in there. I think for now im gonna keep the nerfs just so i dont run over my foot (i do a good amount of trail riding) but im going to look into an axle... would you suggest lonestar or durablue... ive heard people swear by both

[roperr]

You might want to make up your mind about what kind of riding you are going to do before you plan out your mods. 440 kit + air cooled + trail riding + $$$$.:confused:

[prepracing]

Originally posted by ptillman
You might want to make up your mind about what kind of riding you are going to do before you plan out your mods. 440 kit + air cooled + trail riding + $$$$.:confused:


I agree..... if your gonna trail ride u will need... fenders, airbox,frontbrakes and probably no more than 11:1 compression piston so u can stay on pump gas and I think the new stage 2 is a good overall cam that performs well on all ends

[SHADETREE101]

that is a good looking duner. we don't see enough of those on here, good job man.

[icy1155]

Originally posted by prepracing
I agree..... if your gonna trail ride u will need... fenders, airbox,frontbrakes and probably no more than 11:1 compression piston so u can stay on pump gas and I think the new stage 2 is a good overall cam that performs well on all ends

Well ill be doin a lot of trail riding but i also wanted to get into MX racing at the local track. I think just for ease of fueling i am probably going with the 11:1 compression, thanks cause i didnt know that was the higest u could go on normal fuel. There is a pretty good package for 440 that comes with a K&N air filter, a new cdi, a 11:1 set up for 440 and a stage 2 cam... so far thats what im lookin at

[fasterthanyouex]

wellif you p;an on getting into mx i would go with a 426 or 416..it will rev faster and higher then a 440

[fasterthanyouex]

also do a search on this...you will need new heavy duty studs and such! alot more then just puttin in a new piston

[prolineracing]

yo dude golden west cycle has a 416 kit with a cam that would kill a 440 bored 400. also slip on is not the way to go. they add minimal to no power. get a curtis sparrks or a white brothers. their the best for 400s. also duncan fatboy 4 and trinity are mad good in the power range.

[prolineracing]

also dont take your airbox off. bad move. get a high performance twin air kit they add so much power. also, you can get a um alluminum airbox from rockey mountain for about 200 its light, bigger so you can put your battery in it and you dont have to cut anything. my friend put that air box on his 416 and it rips with an airfliter, cdi and a curtis sparrks. thats all you really have to do

[motoboy66]

Here is what I did, and now two others are going to do the same thing after riding it.

Wiseco 11:1 piston first oversize $100
Hot Cams stage 2 E-bay $100
Cylinder bore $30
Big Gun rev box $114
Stock header ground welds FREE
HMF slip-on $200
Uni filter $30
Cut airbox lid with outer wears $15
remove stock snorkle insert beer can FREE well the cost of the beer

I race B XC and GNCC This setup is very competative in the woods lots of torque, and best of all super reliable. I raced the whole year with no trouble at all A 450 will still pull you in a drag race, but you can get them back once you back in the woods

The Big Gun rev box actually works! I have had 0 trouble with it, unlike the white brothers I had befor.

Thats what I did. If you watch e-bay, you can get the stuff pretty cheap

[icy1155]

So go with a 416 with 11:1 compression, stage 2 cams, a new cdi (not white bros i take it), and i heard the Pro-Flow made one of the best air filters on the market from someone. I hopefully am goinng to be winning a new aluminum air box off of ebay within a couple days and im also getting air scoops as well for more air flow... with this set up would you recommend a +6 degree key. What was that about a beer can instead of the snorkel, and lastly what exhaust system would you recommend for this set up? THANKS SO MUCH GUYS

also how many teeth on the front and rear sprocet would you suggest, i currently have 14 on the fron and stock on the back

[icy1155]

Ok, so what pipe would everyone reccomend for a 2001 400ex with a 416 11:1, Stage 2 hotcams, +6 degree key, gt thunder cdi, and k&n air filter?

[fasterthanyouex]

seem every1 likes HMF but i personally like my DMC.. it is mafufatured nice and have a nice sound..with the quiet core. Even with out the quiet core it still has a nice sound but is alot louder:devil:..but my favorite pipe has to the maxwell ..it rocks:cool: :D

[ZeroLogic]

dose that thing actually work good?

[prolineracing]

yo dude white bros cdi is the best out there now. definality get scoops, 416 with a stage 2 cam, white bros carbon pro, curtis spaarks, or a duncan racing fatboy 4 are the pipe you should get. i have a fatboy 4 and it sounds great and i dont have a bore and i kill my friends 416 bore haha