i need to keep up with 450s

[PowerJunkie]

ok heres what i want to do i need all the help i can get. my freind has a yfz450 and im stuck with a 400ex because i to young to drive to get a job anyway heres what i came up with so i could keep up with him and rev as fast as him.

1 Yoshi pipe
2 yoshi headers
3 k&n filter
4 jet kit for carb
5 rev box
6 piston 11:1
7 cam
8 lightened fly wheel
9 port and finish head

1 is a pipe and header even worth it becuase of such litle gain?
2
3 k&n filter i have no questions
4 jet kit what do i need?
5 rev box what company should i get?
6 is wiseco a good one and what is the highest compresion that i can have so i can just use super gas not race fuel?
7 hot cams stage one i gess?
8 never even heard of lightened fly wheel where do you get it done is it worth it how much does it cost?
9 where do you get it done and how much does it coast

[FoxRacing81]

1 Yoshi pipe
2 yoshi headers
3 k&n filter
4 jet kit for carb
5 rev box
6 piston 11:1
7 cam
8 lightened fly wheel
9 port and finish head

1 is a pipe and header even worth it becuase of such litle gain?
2
If you plan on doing motor mods, (which you are), an aftermarket headpipe will help increase the power out of your motor. In my opinion, it would be worth it.

3 k&n filter i have no questions
Alright..

4 jet kit what do i need?
Kinda depends. Most people will say not to buy a jet kit because there is no need for all the jets. I'm not sure what the stock jetting is, but I would go up a decent amount in the main jet, run it for a little, and see where it is at. From there, determine whether you need to go richer or leaner. You could simply buy individual jets from your dealer and post your questions on here


5 rev box what company should i get?
I have a white brothers and I like it a lot, except whenever your battery is low, your quad will not start and it will backfire. Most people wills ay GT Thunder is the best.

6 is wiseco a good one and what is the highest compresion that i can have so i can just use super gas not race fuel?
Wiesco is an okay piston company. I guess you could kinda compare them to a store-brand product. There cheaper then all the rest, but then again you get what you pay for. Wiesco would be fine, but I would go with Ross or JE.

-I'd also reccomend an overbore if you haven't considered it. 426 provides the most power and is cheaper then 440. You can get a kit actually from C&D Racing that comes with 426 11:1 Ross or JE piston kit, Cometic Top End Gasket Kit, and a new sleeve if you want. With 426, you do not need to resleeve. But it is optional. Resleeve will cost around $120 and boring it out will prob be another $40-50, if you don't resleeve, it'll probably be the same to bore it. Quite a few members also have a 416 kit. Something else you may want to look into.-


7 hot cams stage one i gess?
Stage one would be fine.

8 never even heard of lightened fly wheel where do you get it done is it worth it how much does it cost?
I have heard of it being done but I do not know if it is worth it nor how much it cost.

9 where do you get it done and how much does it coast
There are many places to get it done. I believe a member on here with the forum name mikeboone ports 400ex heads. PM him and ask he may be able to. I believe GT Thunder does also.

If you have anymore questions, please ask.

-Justin

[koschak]

I was told the big gun rev box over other after market ones is like adding an aftermarket one compared to stock. It supposedly like adding another gear

[hondardr4life]

Ok, I'm not a 400ex expert, but I will give it a try. I am assuming your 400ex is all stock.

1. YES a pipe and header combo is well worth it, but a slip on is better with 400ex's unless you do a 440 kit, or a 426 kit.
4. Just buy regular Kehin jets to run in it, don't waste your money on a jet kit.
6. Wiseco is a good piston brand, and you have to run 11.1 compression or less to still be able to run super pump gas. Just a Wiseco 11.1 standard bore piston WILL NOT make you keep up with a yfz. To even come close, you need to put in a 440 or 465 big bore kit with a stage 2 hotcam. I believe Duncan makes a whole new jug that you can buy that is already bored out to a 465, and it has the same thickness as the stock cylinder wall, so it is very reliable. With a bore as big as a 465, you would need a bigger carb to get real power out of the motor, so I wouls suggest an Edelbrock Doug Eichner 440 carb, then just change the jetting on it a little to run well with the 465.

I think that a 465 might be able to take a yfz, but like I said, I'm not a 400ex expert. Thats about all I know about 400ex's

I personally would suggest the Duncan 465 jug, and a stage 2 hotcam, then get a good race port and polish job, the Doug Eichner carb, Outerwears airbox cover, and then to top it all off, a Curtis sparks X-6 full system. Just the motor work alone will probablly cost you around $2000, then add another $1000 for the pipe, carb, filter, cover, and other misc. parts. It will be pretty expensive, but that will be one bad***** 400ex, and it would be well worth it.

Well, I hope that helps- Hondardr4life

[koschak]

save some money for suspension though, its not all power its how it handles through the terrain.

[hondardr4life]

All of the stuff I put is for if you want to beat your buddy with the yfz. If you just want to come a little closer than you are now, but still not come close to beating him in a straightline drag, I would suggest a 416, its cheap and adds good power.

[FoxRacing81]

Agreed...I say you first buy an exhaust. Next, buy some elka front shocks...see if you keep up then..if not, then buy a cam and port/polish the head and drop in a stock bore 11:1 piston.

If you still can't keep up after that, practice practice practice! If you practice until your better then Dana Creech and you still can't beat him....maybe its time for a new quad...?


Or, if you want motor mods, read my first post hahah.

[bakeen]

If your drag racing then all the motor mods suggested above sound good and suspension wouldn't be as big of a deal. But if your MX racing then get a new pipe/filter and re-jet but then focus on suspension (New shocks, wider A-arms) before you do anything else to the engine. MX is much more than just raw power and speed in a straight line.

[PowerJunkie]

mx610ex how much r thoughs 426 big bore kits their web site is under construction. and all thoughs mods you said you think there the best and how close do you think ill be able to keep up with him?

[PowerJunkie]

ok heres my plans but i have to think about it because it might just be worth it to save my money to get a yfz.

Engin
yoshi pipe
yoshi headers
k&n
main jet
gt thunder rev box
port polished heads
hotcam stag 1
ross 11:1 piston

suspension
elka front shocks /triple rate i gess?
long travel front a arms /what brand?
rear longer axles /what brand?

this is still my rough draft so tell me what to change no big bores im to scared of heat.

[whiteflash]

Originally posted by PowerJunkie
ok heres my plans but i have to think about it because it might just be worth it to save my money to get a yfz.

Engin
yoshi pipe
yoshi headers
k&n
main jet
gt thunder rev box
port polished heads
hotcam stag 1
ross 11:1 piston

suspension
elka front shocks /triple rate i gess?
long travel front a arms /what brand?
rear longer axles /what brand?

this is still my rough draft so tell me what to change no big bores im to scared of heat.


i hope you have a very large bank account. i suggest doing it one by one ex: pipe,filter,jetting then piston, cam, etc...good luck

[PowerJunkie]

ya your right its the suspension that gets me its way to much for me maybe some wheel spacers instead intill i can aford better.

[400exredrider]

uggh,,,, there are alot of good setups to make it "keep up" but if you want it to "keep up" your first going to have to keep it cool,,, all of this will cost alot of money, id reccommend stepping up to a 450, once a 416 or 426 is fully built it will take on stock 450s but when they add a pipe, which most will cause like 99% of the ATVers end up with a pipe,,, thats just an exaggeration but you know what im sayin,,, i have both and after the hassle of the 416 id almost tell anyone else to just go to a 450 cause a 416 that will keep up will cost you. up to you tho,,, i mean i love the 416 but i love the 450 more.

[400exredrider]

and on wheel spacers,.,,, big NO,, dont mess with wheel spacers... worthless IMO

[bwamos]

My take.. is that it will cost you more to upgrade your 400ex to keep up with the 450's then it would to sell the 400ex chalk up the difference and buy a 450.

With the price difference you could even add on some aftermarket. ;)

[FoxRacing81]

Originally posted by PowerJunkie
mx610ex how much r thoughs 426 big bore kits their web site is under construction. and all thoughs mods you said you think there the best and how close do you think ill be able to keep up with him?

I think you'll be close, but I doubt you'd beat one. You'd prob hang with him with those mods and if your a good rider.

Well, I think just for the 426 kit (I bought a new crank and rod assembly because mine needed one) but just for the 426, I think it was somewhere around 250 from C&D. Your looking at 250, (assuming your resleeving), 120 for resleeve, 40 to bore, thats a total of $410 not including whether your doing the work or someone else...then you could add in labor charges..

Then for a cam...I believe they were in the area of $150 or something?

So $410 + $150=560...now for labor..most people will say to buy a manual and do it yourself to save money...but I'd much rather let someone like my mechanic who's been working on these for a long time do it. I'd be too afraid of messing something up...but I'm sure if you'd take your time and do everything right...it'd be fine.

So, about $560 not including labor...then around another wat...$400 for the pipe?


-Justin