cheap upgrades

[hellshot00]

well i finally got a job and im finally going to have money to spend so im wondering what r some real good upgrades that wont burn a hole in my pocket that will have a very noticable power gain or make the 400 run better in any way thanks guys!

[slightlybent47]

What kind of riding are you doing?
That’s the most important thing when considering modifications.
I’d do the suspension first, there is more motor then there is suspension to handle it in the stock form. But I think the sparks timing key bumps it up some for a small price but I have never used one. A pipe is not a good cheap up grade and won’t do much without other mods to go with it. The rev box is a waste of money on the ex there’s not much power up top on the ex anyway.
Grind the headers and remove the air box lid and maybe re jet would be the cheapest mod.

[3400ben]

Define cheap?

[hellshot00]

i do mostly trail riding where torque is way more use and cheap maybe like 200 max

[ridein'red7]

grind header welds, air lid and put outerwears on it, keep an eye for a after market muffler probly the best you can do

[3400ben]

Originally posted by ridein'red7
grind header welds, air lid and put outerwears on it, keep an eye for a after market muffler probly the best you can do
I disagree on getting a muffler. Most slip-Ons you lose power. I would get better rear tires before a slip-on. The stock tires get no traction. You can have all the power in the world but if you can't transfer it to the ground it is a waste.IMO

[hellshot00]

that is a good point ben i was planning on getting new rear tires as well but just an opinion is it worth paying the extra money for holeshots or are razrs just as good?

[ridein'red7]

well he wanted power not traction lol and i personlly like razrs better they seem to be more "sticky" on wet things like rocks and tree roots and goo great in muddy trails

[slightlybent47]

Traction is not something to be overlooked, if your tires are worn then it can feel like you need more power. New tires do make a big deference, post a picture of what you are running so we can see if you’re going bald. lol

[slightlybent47]

If you like torque then a gear change may do you some good also.

[400exkam]

Originally posted by ridein'red7
grind header welds, air lid and put outerwears on it, keep an eye for a after market muffler probly the best you can do

I am new to the 400ex and quad world. What is the advantage of grinding the header welds?

[hellshot00]

i have stock tires on it still i was planning on getting tires soon anyway but since he brought it up it made me wonder and i was plannin on goin wit razrs for the cheaperness

[slightlybent47]

Originally posted by 400exkam
I am new to the 400ex and quad world. What is the advantage of grinding the header welds?

Welcome to the site 400exkam, if you take your head pipe off and look inside where the collar has been welded on. There is a weld in there and It restricts the air flow and reduces power. But this is just a small amount of restriction so it's not much of a gain, but we all seem to come down with the same sickness and want more power so we try every thing possible to get more out of our scooters and this mod is free..

Look up at the top of the page and click search and there are some threads that show how to do the mod.

[slightlybent47]

Originally posted by hellshot00
i have stock tires on it still i was planning on getting tires soon anyway but since he brought it up it made me wonder and i was plannin on goin wit razrs for the cheaperness



When I put on new rubber it always feels like I gained 5 or 6 hp, having new sharp edges on the knobs makes a big deference. I think you’ll be surprised at the deference.

[hellshot00]

how much does grinding down the header welds help? and yeah tire are def. coming before anything else they do help alot

[slightlybent47]

Originally posted by hellshot00
how much does grinding down the header welds help? and yeah tire are def. coming before anything else they do help alot


You won’t really feel any deference if that’s all you do. it’s all about getting a ¼ hp here and 1 ½ hp there and it all adds up. if you do that and take the air lid off it will feel a little peppier on the throttle response, that’s about all you’ll notice. But hay every little bit helps and these are free to do.

[woodsridn400]

I did the sparks advanced timing key, great for the money. If you check on the used parts page on here you can come across pipes, wheels, shocks, and everything else pretty cheap usually. But i think too suspension and traction is a big player on the 400s. But a pipe always looks and sounds great too :)

[slightlybent47]

Also with this mod you may bump your main jet up from I think stock is 148 to a 150 to compensate for the slight increase in air flow.

[slightlybent47]

Yeah used parts can save you big bucks, I buy used parts when I can but sometimes you have wait awhile till you find what you’re looking for.

[tri5ron]

For around 200 bucks, you'd be best served getting a set of good front shocks, adjusted to your weight, set the ride height and you'll be able to ride much happier.

Another 200 bucks, for a decent steering stabilizer will improve on that even more.

And another 250 bucks will get you a 450r carb, airfilter, outerwears, and Sparks+6 key.
Do the headpipe grind, (free), and pick up a decent slip-on used if you can.
You'll be up around 30 to 31 HP at the wheels, instead of your 24 - 26 stock HP.

Do all of this, and you'll be pleased with the modest HP gains, improved throttle responce, and greatly improved handeling.

Your bike will be a respectable Trail / XC machine, and you will still have a near bullet proof, highly Reliable machine, still running on pump gas.

Yeah it does cost a little money to modify, but you can save alot with the MANY used good parts that are always available.
And you still end up with a great macine that will last many years of riding fun.

Work on improving the handeling first, then go for the power gains.
hope this helps.

[ish416]

I completely agree with tri5ron. Get the suspension and handling mods out of the way and then start saving up for the engine and other go fast goodies.

I have a fairly well modded 416 and I can tell you from personal experience that replacing the stock front shocks with kfx450r shocks is the absolute best bolt on mod for an EX.

I purchased a set for $120 and could not believe the difference that they made in ride quality and actually cut 8 seconds a lap on a mixed xc/mx style course that is about 1.5 miles long.

I would then purchase the Sparks timing key (http://www.alwaysopenmall.com/layouts/02/unsecure/item.asp?SiteID=223&DepartmentID=85&CategoryID=949&GroupID=7033&ItemID=31633&StartNum=1&Sort=&ShowPics=0&ListByCode=1&Brand=&GenderAgeGroupID=0&MaxPrice=&SearchString=&ItemCode=&IsOnlyOnSale=0&FromHomePage=0&FromFamily=0&ProductFamilyID=0&RelatedItemID=0) . Here is the Timing Key How To. (http://www.atvriders.com/articles/timingkey400ex.html)

Then, I would do the free mods, choke removal (http://www.atvriders.com/articles/choke400ex.html), which will work on 99 - 04 EX's. I am not sure if the carb was ever changed on the newer ones. I have heard it was and then that it wasn't. So do check or maybe someone with a newer EX can clarify this.

Then do the header grind and remove the airbox lid if its safe for where you are riding. Also, if you do remove the airbox lid, you will need to rejet the carb.

Then with any money left over you could replace the front sprocket with a tooth smaller to give you a little more acceleration at the cost of about 4 mph top speed.

With just the sparks timing key, the free mods; header grind, choke removal and airbox lid removal a rejet and a sprocket down on the front, you should be able to pull stock EX's with a slip on exhaust.

Of course, if you need tires, there is no point in adding more power when you wont be able to use it.

[450Rida]

btw dont remove the airbox lid, you actually make more power with it on. well more usable power with it on. with it off you gain a little in top but lose in the mid

[tri5ron]

Originally posted by 450Rida
btw dont remove the airbox lid, you actually make more power with it on. well more usable power with it on. with it off you gain a little in top but lose in the mid Can you give an example of this with any verifiable data ?

[3400ben]

Originally posted by tri5ron
Can you give an example of this with any verifiable data ?

X2

[trailrider894]

Originally posted by 450Rida
btw dont remove the airbox lid, you actually make more power with it on. well more usable power with it on. with it off you gain a little in top but lose in the mid

uh.... i think somebody has been drinking it up a little bit... Remind me what color powerband you have again? :huh

[trailrider894]

Originally posted by 3400ben
I disagree on getting a muffler. Most slip-Ons you lose power.

I would love to see your logic in this... i TOTALLY disagree with you. Please explain how this would make you lose power?

[tri5ron]

Originally posted by trailrider894
I would love to see your logic in this... i TOTALLY disagree with you. Please explain how this would make you lose power? X2 , can't wait to hear this one explained.... http://i111.photobucket.com/albums/n148/tri5ron/rotflol.gif

[3400ben]

I should of said some pipes you will lost power. There was a 15 pipe shootout with hp rating in the 400 forum that someone posted i will try to find it. I did a search but have not found it yet. If you remember which one it is post it .

[clemsonteg]

Originally posted by 3400ben
I should of said some pipes you will lost power. There was a 15 pipe shootout with hp rating in the 400 forum that someone posted i will try to find it. I did a search but have not found it yet. If you remember which one it is post it .

This what you're thinking of?

http://www.260111.s5.com/testtrx400escapes.htm

[3400ben]

Yes thanks for posting.