The trade for a Raptor idea is a bad one. Sure you'd get some more power, but you'd loose all of the good handleing traits of the KFX. The only reason to trade for the VForce would be either you're a big guy, or you want the auto clutch. Don't do it for speed reasons. You will be faster on the 400. The V might be faster in a drag, but deffinately not in the dunes(they have serious traction problems). About your engine, the way you are sounding to me is that you want a rocket with just some small mods. Don't get upset with the people giving you advice and deffinately don't accuse them of not knowing what they are talking about. You asked, they talked. Every one of the suggestions made in this thread are good, sound advice. Your KFX is a mid sized mild four stroke. You will need to put substantial money into it to get the power that it sounds like you want. With the KFX/Z, nearly any mod will be mediocre gains, it will cost alot, and you will still have a very dependable bike as long as the enternal mods are done right- and it's kind of hard to mess it up so don't stress over reliability unless you get into stroking and major valve work.

It seems to me that you are wanting to get it back from the shop, jump on to take a spin and come back with an ear to ear grin and a moist spot on your pants. To get this from a KFX400, my suggestions would be to do everything that has already been told to you. 440, cams, port and polish, carb, and cdi box. If this combo is put together right, you will be what I like to describe as pi$$ on yourself happy- ya know, like a jittery little lap dog. And you will still keep a high level of reliability- sure, it's not as reliable as stock, but it's not as slow either.

Otherwise, there is not a lot of horsepower just waiting to be released with your engine- it needs to be created. Hence, if you just go out and by a two part combo like carb and cam- or a cdi and port-n-polish; little things like this will add up and make a difference, yes. But you will be altimately be saying, "Wow, I spent how much for this?" And then you will still be searching for the next peace to the puzzle.

JP

 

My comment concerning people who do not know much about the KFX400 was not intended for posters to this thread. If it sounded that way I appologize it was aimed at the so called proffesionals who all have a different answer to the same question. I started this thread in this forum precisely because of the knowledge available here.

Your suggestion concerning the trade in or up is helpful and informitive however your suggestion concerning my quad is a bit on the safe side, a little light. Of course I can go all out spend thousands and pump every mod into my quad, short of alchohal, and of course it will scream. Im not looking to do everything all at once I want the most bang for my buck. In short im looking for the next step. What I dont want to do is put another k into my bike without noticeing a real difference i.e. exhaust/intake/re-jet. Some say I stand to gain the most with a new carb others (sparks) says its the CDI thats holding my bike back and even others still say my biggest problem is with my head (the one on the bike [img]i/expressions/face-icon-small-smile.gif[/img] my problem is I dont know who is right or who is just trying to sell me something.

 

It's cool. My point was that any pair of mods that you get are going to be about the same, so just go ahead and pick. If you want MY view of the best bang for the buck, I'd say get the carb you've got bored out and then maybe throw in the cdi. Any fair machinist will be able to bore out your carb (usually around 2mm) for about $20-$35. You do not need to go to the overpriced dealerships, the only important thing is to not bore as large or larger than the slide valve. And then the cdi isn't more than $135, right? This way, you'll be able to throw some more fuel in there and also let it pull a little higher into the rpm's. Very inexpensive too. The carb mod usually works well as long as you jet it properly. Don't expect to get the same power out of your stock/bored out carb as you would for the Kiehen, but don't forget how cheap you got it either. Then with the money you've saved, get the cams. If you do this, you should be able to stay under $400 and yet still see a reasonable gain. My estimates are around 5-6hp.

I don't expect you to do this, however. Most people are afraid of ideas like this because of one of two reasons. A.- It's not advertised, because it doesn't make alot of money. B.- Their afraid of getting their hands dirty for the 15 minutes it takes to pull the carb.

I consider this to be weak.

Good luck,
JP

 

youre willing to spend a grand right?
then you need to have the head ported as well...add the ported head and the cams with the carb and the cdi and youll be impressed...

 

If your willing to do a grand like vquad mentioned, then follow his advice. The mods that I listed with a well ported head will give you an extremely strong running KFX.
JP

 

let us know how it turns out!!!

 

Im liking what I hear. What you guys suggest touches on a little bit of everything without going all out. I get the cams and the higher reving CDI but take a short cut on the overpriced carb and head work. I'll check with the local machine guys and see if they want to work with the carb. The head work I already know can be done for 500 but if I only have it ported im sure it will be much less.

 

hey sandmudandhills, what pipes and main jet sizes are you using? and what is your intake setup?
ive been researching for months tryingt o figure out what to do to my bike .. it is stock now... but i know what im going to do when the time comes... so i dont know first hand.. but i KNOW what everyone has to say as i have been researching for llike 4 months.

 

Sell it, buy a Cannondale with all the updates, the difference should be less than a grand if not straight up. Thank me later. [img]i/expressions/face-icon-small-smile.gif[/img]

In all seriousness, everyone seems to be pointing you in the right direction. It will cost a lot of money to get it to midly modded YFZ performance though. I think you are trying to make up ... 12 or so HP. It won't come easy or cheap, or with a warranty. A trade up will probably make you the most satisfied in the end. I'd hate to see you have 3k in your Z before you were merely even all the while sacraficing reliability, and getting none of that investment back on resale.

All about what you want though. From my eyes, you are 1k deep into a couple thousand dollar hole that you aren't gonna be happy in...

 

Funny you should mention that. I have spent the last 2 days searching for a C Dales speed or glamis with absolutely no luck. The best I could do was an ATK distrubutor who can get the new ATK440VR, its the Speed with all the ATK refinements, but he wants 7495+250 assembly and 600 frieght/tax.... Im seriously considering it but thats a hell of a lot of money. Its a tuff decission but either way it comes to about $3000

As for what I have already done. I have the FMF power core 4 head pipe and silencer. I installed a K&N filter/pre filter and removed my lid. I also installed the d165 main jet from dyno jet and the needle that comes with the kit on the 3rd slot. The bike runs great as is and it sounds awsome. The only way I know its more powerfull is it pulls wheelies a little easier in 2nd gear and I hit the rev limiter a lot now but I didn't make up much ground on the YFZ450 in fact after second gear he's at least 3 quads ahead of me and pulling hard.