NewBie MOds

[Jdev3407]

Hey Guys, just bought an 05 400ex and was wondering what good aftermarket parts should i put on it to make it go faster maybe a lil snappier we do alot of trail riding here in PA and its pretty rocky sometimes but i dont race . im not looking to spend thousands yet just a couple 100 for starters and was wondering what sites have good parts for these quads??? i was thinking about a sparks advance timing key???? and it already has a lexx mx slip-on on it but i kinda wanna go HMF Full i want loud and power??? please help

[jcmoore82]

you should most certainly get the sparks timing key. i just installed one on my 02 and it is well worth the money, not hard to install either. Is your bike jetted? you should look in to that. A rev box is a good investment also. motosport.com is a good site.

[Jdev3407]

i dont think its jetted and not really sure how to jet new to it ive ridden alot but not mechanical stuff but when i let off the throttle it kinda backfires a lil ?????

[jcmoore82]

well most all jet kits come with instructions, its not that hard to follow, i never did one before i did mine. and i got it right.

[Jdev3407]

were can i get jet kits like what are some sites and what brand do u guys recomend

[gojk]

I would recommend dropping 1 tooth on the front sprocket if you right mostly tight trails with few long open areas.

Secondly, I don't think I would by a jet kit, just by the individual jets. Jetting is very trial and error. What is perfect on one machine, isn't necc right on another. Plus if you worry yourself on perfect jetting, you will go insane as the weather changes along with elevation changes will modify your jetting needs. Get the jets close and to a point that it isnt doing harm to the engine and you should be good.

Third, buy a slip on silencer. Plenty of them on the market, some good, some not so good. There are plenty of "my pipe is better than yours" threads, so you can see why each person thinks each is better. Some of the brands to look at: HMF, Yoshimura, Duncan,Pro Circuit. And to go along with it, look for an aftermarket air filter. I like K&N if you have the prefilter on it, some prefer UNI. If you like the cotton type get the KN, if you like sponge type, get UNI.

[bigbad400]

backfire on decelerartion is a sure sign that you need to jet, HMF all the way!!!!
i would also def. recommend the sparks key, easy affordable and great gain for the price.

but on the other hand, i would first off make sure you got skids with the rocky woods, especialy the swingarm skid, but then i would go with some trx450r front shocks or those pogo sticks will bounce you around so bad, there around $200 anytime i ever saw them, usually on ebay. there another great buy, im saving to send a set to gt thunder to get revalved and sprung to my weight and riding style.
but for your application the skids first of all might be the best way to go. protect your machine, belly skid, and swingarm skid at least, the a arms are a little more protected but def. worth buying the skid rather than buying a a arm set. i hope i was some help, and by the way the black chrome HMF looks sweet on a yellow 400

but i have black and yellow everything......im just not a fan of red plastics :D

definatly just buy kehin jets too, the sizes are not the same from brand to brand.

the cdi or rev box as some call it, is also a good choice i got mine on ebay as a pair with a high performance coil, just go to ebay and type in 400ex AMR cdi.
i got the stage 2 combo pack they have a stg 3 too if you want to do a big bore in the future. mine was 105 shipped for the combo and i love it great throttle response.

[Jdev3407]

Alright i got a swingarm Skid and a belly skid just under the engine i was thinking of going full and definetly want the HMF FULL SYSTEM was thinking HMF BALANCE SERIES and they come with the jets u need

[buster024]

If you're trail riding, grab some nerfs too. They'll save your bacon countless times. A good pipe will treat you right as well. After that, suspension, arms, new handle bars (the stock ones are way to small, and force you to ride like a turd), good tires (Maxxis or Holeshots with a heavy ply if you are ridin' the rocks).
Use the search feature or cruise through the how-to section to learn how to jet. It's easy, just time consuming. Look into picking up a 450R carb. They are a great upgrade as well.

As far as god shops to buy from, Motosport.com & rockymountainatv.com are popular. This site has some great sponsor shops too. Ebay is great for used parts (don't be afraid to buy used stuff, everyone does).

[Jdev3407]

i have tusk nerf bars and tusk handle bars and a lexx slip-on exhaust but im thinking going full HMF

[buster024]

Look into a Curtis Sparks full system vs. the HMF. If you plan on upgrading the engine, you're going to wish you had the Sparks in the first place.

[Sanddraging28]

i totally disagree with buster024. HMF is one of the best full system exhaust's on the market.
with all the 400ex's i have built both for me and for customers the HMF has made better power than the countless other brands i have tried.
spend some time at a drag strip that runs four wheelers or at dirt and sand drags you will see more HMF exhaust's than any other.
i have seen a 3 HP difference between HMF and some of the others on a dyno.
the only downfall of HMF is how loud they are.

Get the sparks key and perform the "free" mods. Open the airbox lid, remove the choke, gring down the header welds, replace the spark plug boot resistor with a piece of metal and I recomend an aftermarket better flowing airfilter. Then jet for it all and it will be a shocker. The Lexx isnt a bad pipe. Its not the best but I would make with what you have right now.

[jelrod05]

willing to sell the lexx pipe if so how much

[buster024]

The absolute very last thing I want to do is to start a "which exhaust is better" war. I just think it's wise to recommend alternatives that new riders may not be familiar with. HMF is definitely a popular brand that everyone has heard of, & I don't think everyone just starting has had the opportunity to hear about Sparks.

Jelrod, ask around, call GT Thunder, call C&D racing, call HMF and Sparks directly, and then take all that advice & make a good decision. I don't think many people would argue that Sparks and HMF are two of the best products on the market. Most atv circles have those two at the top, with the second tier of still excellent products being Yoshi, FMF, WB etc., then maybe all the rest from there (I'm sure I'm leaving someone good out).
In either case, just make sure you are thinking of your finished product before you make any decisions on high ticket items. I'm paying the price for not doing that, and have a full Yoshi system that just won't handle the engine upgrades that I know I want now. I wish I would have purchased a Sparks (or even HMF) over the Yoshi.

[Sanddraging28]

i agree on recomending alternitives to people new to the sport. but i am also think that those of us that have been around the sport for a while and even those of us that make a living with four wheelers, whether it is by racing, selling parts or building race motors to let some of the new people know the things we have found out the hard way and expensive way. everybody has an opinion on what works best, i know i do. but i try to limit my advice whether it is on a forum or in my shop to things that i have first hand knowledge of. this just happens to be one of the things i deal with all the time since i build drag race and stroker motors for four wheelers

[buster024]

i agree on recomending alternitives to people new to the sport. but i am also think that those of us that have been around the sport for a while and even those of us that make a living with four wheelers, whether it is by racing, selling parts or building race motors to let some of the new people know the things we have found out the hard way and expensive way. everybody has an opinion on what works best, i know i do. but i try to limit my advice whether it is on a forum or in my shop to things that i have first hand knowledge of. this just happens to be one of the things i deal with all the time since i build drag race and stroker motors for four wheelers

I couldn't agree more. Well put.