KLX450R Convert Into KXF450

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KLX450R Convert Into KXF450

Post by 4Strokes » Wed May 25, 2016 4:43 pm

Topic: KLX450R into a KXF450
Author: b_king
Posted: 11/13/2007 06:35:00 AM

I've bought a KXF450 airbox and muffler, still need to find a headpipe. I'm trying to open it up a little cause the stock airbox, as all you XR riders know is plugged up like there's no tomorrow. So in an attempt to do the job properly, I've got all the KX stuff on order to keep this thing looking as stock as possible. Anyways, I'll keep ya'll updated as this little project progresses. It might be a while because I plan to do it as part of my winter tear down and inspection. I'm still riding now!

Reply by JoJo boy on 11/13/2007 11:44:12 AM
Has there been any reviews that have put this thing on a dyno and a KX too? I heard its missing the topend punch but i was wondering by how much.

Reply by b_king on 11/13/2007 4:36:10 PM
The KLX? It is definitely not XR, but it'll chug through most stuff. You have to keep the revs up to get the whole package though. It's not a screamer like a full on moto bike, but how often are you screaming at 11,500 rpm in the trails? I've only red lined a couple of times doing hard accelerations out of corner or on straight flats. The KXF on the other hand is similar power but a lot more on top and a lot less on the bottom. I've rode the KXF in stock trim on the ice, then with a ported head, carb, custom exhaust with Supertrapp, intake mods setup for flat track and let me tell you. That thing is ridiculous fast. The shortened wheelbase for flattrack makes it a wheelie machine.

Reply by b_king on 11/30/2007 06:28:21 AM
Long time no post, I was without a computer for a while. Anyways, I've got the airbox and muffler so far. I am now looking for a headpipe from an 06' because it is slightly smaller than the 07', so I won't lose as much torque. I'm still riding this weekend, and I have next week off so I'll be getting out quite a bit, I've only got 12L of gas left so we'll see how long that lasts, then it's time to take it apart!

Reply by Admin on 11/30/2007 08:44:06 AM
Glad you're okay, b_king! Looking forward to the outcome of your "KLX Tractor" project.

Reply by b_king on 01/15/2008 10:18:05 PM
So got the whole bike stripped. Before doing so though I mocked up the KXF airbox and with my vast knowledge of absolutely everything decided to use a battery holder from an 05 KTM 250EXC which happens to be the exact size that I need. So I will bolt it on to the back of the fender, as KTM does, but using a little fabrication of some BMW parts and some ingenuity and I'll have a battery holder. Now all I need to do is go over the entire bike and get it ready for the new season and hopefully some amateur racing. I tried to keep up on pics of this whole project so I could document it, but the teardown process happens so quickly I'll take some as it slowly comes together. I mean, putting it back together is what people tend to have more trouble with anyways. I mean, any idiot can take something apart right.

Reply by 250f canuck on 01/16/2008 05:31:48 AM
What kind of racing are you going to be doing?

Reply by b_king on 01/17/2008 6:50:43 PM
I'm thinking of trying some enduro's and harescrambles.

Reply by bigggdozzer on 03/30/2008 06:15:16 AM
Does anyone know.i wanted klx but stuck with a kx 450 ,anyhow can i convert this to klx like will the kx do the lighting etc.i have a 06 kx 450 with 30 min on it and has two bros M-7 pipe and etc on it,can i convert this to enduro,thanks tim

Reply by b_king on 05/03/2008 5:19:05 PM
Alright, I've fought and fought with jetting issues and finally found a setup that works, pretty well. I'm going to have to fine tune a little bit after I start riding it a lot. But I've currently got this:

  • Pilot - 45
  • Slow Air - 100
  • Needle - NLZU
  • Main - 145
  • Leak - 50
  • Starter - 65
  • Fuel Screw - 1-1/8 out
  • Pilot - 55
  • Slow Air - 100
  • Needle - JD Red 4th Position
  • Main - 165
  • Leak - 50
  • Starter - 65
  • Fuel Screw - 1/2 out
I've got the Boyesen Quickshot 2, O-ring Mod(thanks Canuk). The White Bros. Fuel Screw was crap, the aluminium ones do not seal properly and will mess up the jetting. So, I bought a Scott's fuel screw, which is brass like the stock one but has a roll pin pressed into the bottom to provide easy adjustability with your fingers.

The electric start works with the Yuasa YTX4L-BS, 4 amp hr. battery I'm using. Smaller than the stock 6 amp hr. The stock charging system on the KLX is virtually useless, it only charges the battery at 13.2-13.3 V. My next upgrade is a higher output stator to provide the battery with some more juice. Hence all the battery issues others are having. I've used a tender since new, so no issues. The KXF muffler is badass, nice snap to it. I'm looking at either the Yosh RS system of the Leo Vince because they both provide a 94dB removable quiet insert. This way I can ride at events requiring a quiet exhaust, then open her up on the other days at the track. Next step through this riding season is getting my suspension revalved for my weight and my style of riding. Prob stiffer rear spring as a start.

A side note: I cannot believe the customer service at JD jetting. Awesome product, a little overprice. I didn't need any main jets, I just wanted the needles, but you have to buy the kit. Anyways, I called and asked for a tech dept. The lady said she can usually answer most questions. I explained my situation with the hanging idle I was having, the modifications to my bike and basically everything else. She pretty much read off the package what the kit for the KLX does for my bike. I said great, I understand that, but that is not my problem. All I wanted was the needle, I couldn't care less about the other jets I get, or the O ring mod that I've already performed. She then explained to me that she was the only one there when I asked to speak to someone else, I found this hard to believe. Reluctantly I bought the kit. If it wasn't such a good product, I would have gone elsewhere, but the genius behind the multi taper needles is awesome.

First ride will be this week or weekend, we'll see how the weather goes. Robb

Reply by 250f canuck on 05/03/2008 6:24:54 PM
Customer service at JD is better if you shoot them an e-mail, usually JD himself will reply and get you sorted out. Rode my WR today in stuff where I could actually open her up, the power from the JD kit is just awesome (with my quiet insert in). Power wheelies are no problem in the first 3 gears, haven't tried the upper two yet. I was lucky with my kit, the recomended setings to start off with were bang on for my conditions.

I've always wonderd about the main jet sizes people claim to run on their 450s, you have a 165 in yours but my 250 runs great on a 185. To my way of thinking shouldn't a 450 need to suck in more gas in one gulp than a 250?

BTW are you planning on going to Madawaska this year?

Reply by b_king on 05/03/2008 10:56:08 PM
It all has to do with fuel air ratio of around 14.7, but I mean just because it is a different engine size doesn't mean it necessarily needs a larger amount of fuel. I have a feeling that I'll have to bump it up to about a 170, maybe 172. I haven't had a chance to go screaming down a trail WFO yet, so we'll see. These settings are basic by the ear and riding in the parking lot and local streets. The Kawasaki Factory race teams have a chart with the stock jetting of each of their motocross and offroad bikes vs. the jetting the Works bikes have, and most are pretty similar, maybe minor adjustments. I too noticed that the 250F and 450F were the same main jet, the KLX was still a 150 or something small because they didn't open up the airbox and exhaust.

Yes, I would have preferred to deal with JD himself, but I'm not a big fan of the email system for inquiries such as the one I was making. Not enough information can be sent across to the other person via email, I like speaking to a person.

I would very much like to do the Madawaska, but I'm sceptical about my pipe as it is right now. I'm sure no one wants me around with a 102dB pipe. I'm certainly not in the market for a quiet pipe just yet, I'd rather spend the money of race gas and other goodies.

Reply by 250f canuck on 05/04/2008 08:58:32 AM
Well nobody checks sound at Madawska, but you would turn a few heads blowing 102db. You couldn't just put your KLX muffler back on for the two days?

Reply by b_king on 05/04/2008 09:52:14 AM
I could I guess, maybe by then I could afford a nice Leo Vince or something. Plus I hate paying to ride, I mean last year it was like $80, pretty ridiculous. I wouldn't mind paying say a $10 trail fee every time I ride somewhere, but I mean $80!

Reply by 250f canuck on 05/04/2008 10:54:32 AM
I guess the argument there is that they provide dinner on Saturday and I think they do breakfast on both days (on Saturday for sure). It is a little pricey, especially when you factor in campsite fees. I split the cost of the site with my Dad and I think the whole thing worked out to just under $100 a person. It's a great ride though, bench "racing" after each day is almost as fun as the riding itself.

Reply by b_king on 07/06/2008 07:16:40 AM
Finally got my idle issue figured out. During the modification process of changing out the KLX airbox for the KXF airbox, I had to reroute the crankcase breather vent line to the airbox. I opted to drill a hole in the boot from the airbox to the carb. Put a small hose fitting from an F650GS airbox and call it a day. Everything worked fine, looked good, mounted up ok. Ran fine except for the hanging idle. Now, typically a hanging idle would be do to a leak in the intake manifold, or possibly in the exhaust. Neither of which were my case, so I had to jet the pilot so rich(55) to accommodate the hanging idle. Well, yesterday while doing a mid season overhaul, I was curious. I had an extra airbox boot and threw that on. Routed the crankcase breather elsewhere. Fired it up. No hanging idle. Now, I was super rich on the pilot. So I dropped it down to a 52, still too rich. I am now going to wait to get my new exhaust system on before I continue to much jetting because I will most likely have to tinker the jetting once I get it on anyways.

I'm still planning on taking pictures of my airbox mod setup and such. Hard to find time with all the overtime I'm putting in, plus I just bought a truck so I'll be doing some work on that. The girlfriend takes most of the time though. Robb

Reply by 250f canuck on 07/06/2008 09:22:46 AM
Whats the main difference between the KXF and KLX air box that would justify a swap? I'm assuming more airflow.

Reply by b_king on 07/06/2008 2:22:18 PM
The KXF airbox is yes more airflow because it is more open. But mainly the actual filter is wider, and because the engine draws the air from the sides of the filter it doesn't really matter how much longer or more open the airbox is, it's how much wider the filter is. This is what will give it better throttle response and more torque and horsepower.

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