Hi,
I have a kfx 450r. I would like more horsepower. I want to keep my warranty. I know that a BIG 3 modification can get me 10-12 Horsepower. I am not sure I want that much. I was think of doing a Fuel ATV air box+ intake + filter and a Power Commander 3. they told me I can expect 4 hp from that. I would settle for that but the air box mod qill void my warranty and it not the fastest thing to to take off. I am think of intalling a full exhaust system . I have a few questions for you experts:
1) will it void my warranty?
2) can I get a horsepower increase? or will it harm my engine because it will run too lean/rich
3) if I decide to add to the exaust a power commander does it improve anything or do I still need more air for the extra fuel? Let us say you tell that I do need some more air, is ther anything I can buy that will not be too obvious and that will improve air flow: for example I am thinking a K+N air filter with some extra holes in the air box, that should allow a little more air?

As I said I do not want to get the full 10-12 horsepower, do any of you have suggestions for obtaining 5 horspower or so?

 

well 4-5 hp is not that mush. i have a full yoshi exhaust on my kfx400 and its not that big of a difference. noticeable but not oh my god. your factory warranty isnt that great is it? i thought they were only 6 months. if your gonna mod it, go big or dont go at all. more power the better-- i feel.

 

hey,
i have the extended warranty. 3 years. it was a good deal. only 15 $ ( CND) per month more. you have any kind of numbers for the exhaust? 2 hp?
you put a full exhaust on, does that make the engine run too lean?

i'm going to explain to you why i need the extra hp. I decided to gear the kawi for max top speed. i put the 15 tooth front ( stock 14) and 33 rear ( stock 39). everyone beats me till 100 km/h, after that they are gone. I need some more hp to get there easier. i would settle for 5 if it's possible, otherwise i will go back down a tooth in the front.

 

drop the 14 back in and see if that cures yah .. i read that 3 teeth on the back sprocket are about equal to 1 tooth on the front/...

so you went up 1F(or 3 R) and 6R (or 2F) which means you went up effectively 3 teeth, or a 17T front...

so, you can experiment...
14 and 33 is like having just a 16t front ...

 

for the easy mods I would go with a dasa complete exhaust (best for the kawis) and power commander and take the air box lid off. You can also replace the air intake tube with the ltr450 tube flows much better. You should easily get the 5 or a little more hp for around 700 bucks. Hope that helps.

 

1st off just adding the big 3 will not give you 10-12 hp gain. Its more like 5 to 6hp. Also any aftermarket header/pipe will void your warranty & same w/ the pc III..

Full exhaust is a nice place to start, The stock header on the kfx is nice & I hav seen some gains just w/ a slip on, but w/out a intake even the DASA does not add that much hp, so that might be a option for ya..but just to put a exhaust on will not hurt your motor....

A pcIII will add hp if you have the right map for your mods & altitude where you ride, all motors are big air pumps the more you can improve the flow of air the more hp you will make & the kfx is very restricted in that department...I used a EHS Lid on my stock air box thay work nice....

when I was putting mine together my 1st build was dasa pipe/header, ehs lid 15/33 gearing (we also like to go fast) but I found that the 15/33 is to tall for the kfx...w/ the mods you want to do w/ just a small hp increase you might want to try 15/35, atm I run 15/34s & just hitting the rev limiter w/ my mods & tune..

 

I got 11 hp with the big 3 on my kfx so maybe your dyno guy does not no what he is doing. Of coarse all the mods void the warranty but the 3 mods are easy to switch back in forth. I agree the stock header is nice but it is not steeped and thats were the extra power is made. hot cams are next for me.

 

Well like I said just boltting the big 3 on does not add 10-12hp...after dyno tune sure, but just to bolt them on and then guess @ a map, I would like to see it.

As you can see w/ my 1st Dyno run I only made 37hp w/ the big 3 just boltted on, Stock is what 32ish & after Tune I made 43hp so I think my dyno guy know's his stuff....

 

right, but you shouldn't do any mods and run just a map. The map might be close enough were it seems to run better, but it might be dangerously lean to.

 

check out this intake im running, this is a great piece of equipment, glad i got this instead of the fuel one.
http://cgi.ebay.com/ebaymotors...X:IT&item=350123612953