kfx 450r exaust air filter mods

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kfx 450r exaust air filter mods

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kfx 450r exaust air filter mods - 8/18/2008 7:19:45 PM

percykfx450r

Posts: 5
Joined: 8/16/2008
Status: offline

Hi, I am a new in the atv world. I have just bought a kfx 450r. I am not really happy with it. I have raced it against a 03' Polaris 525 and a yama 450 yzf. Both beat me. At the take off and up to about 60 km/h ( 35 m/h) I was ahead and then they got me. In top speed it was worse. I never really liked my gears so I increased the front sprocket by 1 tooth and I removed two teeth from the back. I am able to best the 525 know. It is really good at top speed. My question for all of you is as follows. I am lookinbg at buy these " full exaust" systems. I have been reading that you can gain around 20 % power all accross the rage. The only problem is that you have to reajust the efi. Ehicjh means I will probably loose my warranty. I caLL DRAGONFIRERACING And they siad that the fuel inject does not need to be reajusted. They say the computer can conpensate. What do yopu guys think of that. I have clearly read an article by F2 racing that say it is even dangerous not to reajust the efi? Any thoughts?

Post #: 1

RE: kfx 450r exaust air filter mods - 8/19/2008 12:12:53 AM

Fastford

Posts: 216
Joined: 1/3/2008
Status: offline

I would look around for a chip of some kind to get a richer mix. Unless you got an O2 sensor the EFI isnt going to beable to adjust that much. I dont know anything about the KFX but my DS dont have an O2 and I had to clip a wire for a race map which added the fuel I needed for a pipe.

(in reply to percykfx450r)

Post #: 2

RE: kfx 450r exaust air filter mods - 8/19/2008 12:30:51 AM

SCboys

Posts: 423
Joined: 4/3/2008
From: Andrews, South Carolina
Status: offline

just get a fuel programmer thing.

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(in reply to Fastford)

Post #: 3

RE: kfx 450r exaust air filter mods - 8/19/2008 12:37:18 PM

BrootGoot

Posts: 2319
Joined: 2/1/2007
From: spartanburg, sc
Status: offline

the efi adjusts for air density, but does not adjust the fuel / air ratio. you will need a PCIII , like i have. there are other brands, but i like the dynatech pciii because its programmable and adjustable.

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(in reply to SCboys)

Post #: 4

RE: kfx 450r exaust air filter mods - 8/19/2008 3:32:21 PM

percykfx450r

Posts: 5
Joined: 8/16/2008
Status: offline

Hi,
I've calling around. I have talked to dragonfireracing, motoworks, big gun, pro circuit, fmf, trinity racing and yoshimura. I am interested in either yoshimura or motoworks. My first choice will probably be yoshimura because they have two types of efi. One of them has two settings and the other is the type of efi where you manually set 6-8 diffrent fuel settings. For example you can get a setting for full throtel or accelerations... I prefer the first because it's more simple. Also I have been reading on their web site that just the "simple" efi can get the horsepower form the stock 36 to 40.1. That is already a pretty good increase. It's around 12%. It is higher than any of the other efi. It seems real easy to intall too. There is another good thing about the yoshimura "full system": it seems that my efi has two settings and it seems that the exhaust has two settings two. what I mean by that is that you remove some peice from the muffler and then you get the full power. You can set the kfx back to almost original settings: not much fuel wasted. The only thing I fined really annoying is that I have to repack my muffler every 8 hours. I am actual going to ask if I cannot buy the "simple" efi and keep my stock muffler. I don't want to make things real complicated. I use my atv every day. I live in a canadian county that allows atv's on the roads. I use it everyday to get to work. So, somewhere I am reluqtant to modify it. I will have to get soem more info on the matter. Also i have learned that these mods can be tacken off really easyly and they are "unnoticable". I am trying to decide wherether or not to go all the way. I would love to get to that 46-47 hp range( efi 4, exhaust 6-7). I think that the yzf and ( for sure) the 525 will be hiding when I am done with them, but there is just so much work to do. Are there any of you who have done this and is it really worht it when you do the pro/cons. Also if any of you have an opinion on which exhaust system is the best, please tell me.
Many thanks

(in reply to BrootGoot)

Post #: 5

RE: kfx 450r exaust air filter mods - 8/19/2008 3:37:18 PM

percykfx450r

Posts: 5
Joined: 8/16/2008
Status: offline

hi,
of all the companies that make the full system exhaust: yoshimura, fmf, big gun, pro circuit, motoworks... Which is the best? I am not a atv racer. I use it on a daily basis. I would like to get to 45 hp but I do not want a fragile engine. It seems that yoshimura have a two setting efi that increases hp from 36 to 40.1. Do you think that i can still keep my stock exhaust with that efi?

(in reply to BrootGoot)

Post #: 6

RE: kfx 450r exaust air filter mods - 8/19/2008 9:50:24 PM

Joseph Who?

Posts: 350
Joined: 4/10/2007
From: Tifton MF'ing Ga.
Status: offline

Two words.... DASA racing.

Call them, they know whats up with the KFX's. Not the cheapest but probably the best.

(951) 681-1131

http://dasaracing.com/sitepages/DasaRacingKawasakiATVnew.html

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(in reply to percykfx450r)

Post #: 7

RE: kfx 450r exaust air filter mods - 8/20/2008 9:53:02 AM

percykfx450r

Posts: 5
Joined: 8/16/2008
Status: offline

Hi,
Thank for the dasa hint. I called them yesterday. They seem to know the 450r. Theey do mods to the air box too. Yoshimura doesn't and neither does motoworks. They are the most expensive, I think they are around 900 $us. Trinity racing is about the same. Both have air box mods. The others ( to my knowledge don't). For everyone's information, I got the yoshimura exaust all wrong. You don't remove anything from the exasut. It stays as is.
I am still hesitating. I am sttill pretty keep on yoshimura, just because the ecu is so simple. It seems all will get you that 10 hp gain. Dasa and trinity claim a bit more, but they both redo the air intake box. I think that dasa and trinty are the best for heavy mods: valves, cams, bigger engine... I think it may be more than I need. It seems that if you go to my level, the yoshimura/motoworks mods are enough.

I have one more question: I have a rear moose sprocket. I tryied to get the smallest there was. Alll they had was -2 teeth. Does anyone know of a company that goes even lower?

(in reply to percykfx450r)

Post #: 8

RE: kfx 450r exaust air filter mods - 8/21/2008 9:55:31 AM

on2wheels

Posts: 5
Joined: 8/21/2008
Status: offline

I would have to agree on the Dasa pipe.My second choice would be CT racing.Tunable for power and sound.The stuff you are looking at is commonly known as the Big 3.Intake,programmer and exhaust.I would try and get all 3.You'll notice an awesome gain.Fuelmotousa.com is the cheapest place I have found for the PC3.They send it pre-mapped for your elevation and mods.Pretty easy install.Kawieriders.com is a great site with lots of info on your bike.Probably some pretty big discounts from site sponsors on the big 3 too.Keep us updated.Good luck!

(in reply to percykfx450r)

Post #: 9