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2004 kx250 xc build

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whats up guys, i've been building an 04 kx250 2 stroke over the last 2 years full frame and swingarm powdercoat, fcr works suspension front and back, applied triple clamps 3.1 gal tank and a scotts stabilizer. just curious on setup for xc gncc style riding. gear ratios flywheel weight tire pressures ect... and opinions on motor setup, i was thinking about running a high compress cool head with a 19cc dome, what other mods are avail? and what about cdi boxs? any avail? all i can find is a $600 tokoyo mod....

 

 

my bike.jpg 

Edited by gmiller443wv

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There is a guy on here called zzgm33 or something like that who has one.  Look at his posts and hopefully he will chime in on this thread.  He is QUITE knowledgeable on the bike.

 

Congratulations on the bike!

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There is a guy on here called zzgm33 or something like that who has one.  Look at his posts and hopefully he will chime in on this thread.  He is QUITE knowledgeable on the bike.

 

Congratulations on the bike!

thanks i'll try to find him..

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awesome.. makes it alot easier thanks  :)...  any tips on making more power without going with a big bore? any help or recommendations would be great.... 

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i've rode over 20 years but i've just got into racing over the last few, so i'm just now really paying more attention to bike setup, just really looking for feedback from guys with experience with the same or similar bike and riding conditions. biggest thing is getting the motor tuned to where the power is more usable in the woods  but still have plenty of power when i need or want it... and whats a good chain/sprockts set up for xc ? wasn't sure if running a aluminum rear would be a good idea and not sure what chain is a good choice   

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The 04 makes a great offroad bike with a few mods. It already makes good power. Mine and my wifes 04s were stock engine wise except for a 9oz fww on mine and a 11 on hers. We use WER dampers and our suspension has been revalved by WER also. Ive tried Vforce reed cages but ended up going back to Boyeson reeds. The Vforces dont last long and cost alot for replacement reeds. She ran a stock pipe on hers with either a Pro Circuit 296 or a FMF Q spark arrestor. I used a rare Enduro Engineering pipe on mine. We both run Flexx bars. One of the best investments we've made! Another thing we do is run 03 KX250 forks valved by WER. The 03 forks are open chamber and dont have the bladder that the 04 has. They are way better for offroad. Where the the 04 fork has a tendency to deflect off of the little stuff. roots, rocks and square edge holes, the 03 forks eat that stuff up! You can disable the bladder in the 04 forks with good results from what Ive been told. I havent tried it yet. I ran 13/51 gearing on my 04. We use DID Xring chains. They are strong and narrow so you wont chew up your cases and chain guides. We run cheap steel sprockets. No blingy dual metal stuff, those aluminum inner steel outer sprockets are what Im talking about. Clip a rock with one and watch then come apart! My 04 is no longer a 250, I swapped in a 02 500 motor a few years back. My wife just converted hers to a 300 big bore. We also have a 03 and a 07 KX250. The 03 is a good bike but the 07 just mostly sits. Its a quirky handling, hard hitting bike that put my wife on her head a few times. In our opinion, the 04 is the better bike of the 3. We are both A enduro riders, she's an ex Team Green support rider with around 15 years of racing under her belt and I have 30. Where in WV do you live? My father inlaw has a place near Romney. Any more questions just ask.

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Stock ignitions were used and we run Moose HD tubes with 10 lbs for sand and 12 for the rocks (most GNCC events except for Florida).

Her 04 300

IMG_20140408_192240223_zpshl93gnlt.jpg

My 04 500 hybrid before the Flexx bars

2013-03-11111022_zps414500c3.jpg

Edited by zz3gmc
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thanks for the info helps alot. are you having your stock stator rewound or is it aftermarket? i was looking to run a light... u got some good lookin bikes... i'm from the beckley area about 4 hrs from romney.... another ? i had is about installing the front forks... book says 15mm from top of clamp to top of shock tube.. what do you run? i installed it at 15mm and noticed my bars were right on top of the adjusting screws on my forks... and do you know of any aftermarket cdi units??? sorry about all the questions lol.. i've been workin on this thing for awhile its just nice finding somebody that has one and knows about them, i really appreciate the help 

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15mm is where we ran them and yes it just about touches the rebound screw.  Her 04 has a Eline 200w lighting coil and my bike has a 65w Moose lighting coil. When it was a 250 I tapped into the powerjet carb circuit. It puts out around 30w or so and I run Acerbis DHH lights with 2 35W equivalent LED bulbs from Home Depot. You can ride at night at low speeds. Ive never used any aftermarket CDIs, I really didnt see a need for them. I think Vertex makes a CDI. Love riding in WV! I raced the old Blackwater 100 8 times and have ridden several dualsport events there also. Thinking about moving to WV someday. Probably around Romney/Slanesville area.

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i set them at 15 but i added some small spacers under my bar clamps to raise em up a little bit, made me feel better if nothing else... i haven't found an aftermarket coil but i found a guy said he can re-wind mine and get 25 watts i think? do they not offer any kind of high compression piston for these bikes? i built a 125 a few years ago and vertex offered one but i haven't found any for my 250... i'm not expecting to be out running 450s but i'd like to get the most out of my motor... yea over the last few years west virginia has actually became a really good place to ride, we got burning rock atv and hatfield mccoy trail systems in our back yards basically, plus several other great places to ride,, so much gorgeous scenery, let me know if your ever down this way, i work in charleston but i travel all over the state to ride


will any plastic off a newer bike fit an 04? i was wanting white plastic but havne't found any 

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I have an 05 pretty well dialed in for aggressive single track riding.  I agree with the comments above re: x-ring chain and steel sprockets.  I have an efm auto clutch, FWW, RTT damper, ASV levers, and run a gnarly pipe.  Not sure what engine mods you are looking for but I have spent my time tuning the 05 to make linear power from the start all the way up.  I can't imagine riding the tight stuff with a harder hit than the 05 had stock. I messed with jetting for a while, then spent the money n the JD kit and have only needed to tune the A/S since.  Mine does sign off a little early but can now be lugged and has almost instant power.  Well worth the slight loss up top. Mine will easily pull the gnarliest of hill climbs and is a blast in the tight stuff.

 

 No luck on a white rear fender I have been looking as well.  Steahly Offroad has a light kit that runs off the power jet carb.  Enough to run an LED light up front and a tail/brake light in the rear. Easy instructions and has a bar mounted switch.  They also make the fww.  The Hyde racing skid plate is very good.  It is quiet, fits well, and protects the water pump.  

 

Great bikes,   Good luck

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I ran only oem pistons in ours. You can get thinner base gaskets from Cometic that will bump compression up some. You dont need to rewind the coil you just need to tap into the white wire with the red tracer coming out of your voltage regulator on the left side of the steering head. 

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I ran only oem pistons in ours. You can get thinner base gaskets from Cometic that will bump compression up some. You dont need to rewind the coil you just need to tap into the white wire with the red tracer coming out of your voltage regulator on the left side of the steering head. 

 

 

Would I be able to do this on a 99?  I just want a small light up front.  Nothing really powerful, just an option for a little light in dark spots/night would be helpful.

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http://www.efmautoclutch.com/

 

 

The efm is similar to the Rekluse z start pro.  I have a Rekluse on my ktm 200.  So far the EFM has proven to be bulletproof.  Even on the gnarliest of trails it has had zero issues.   It is a little different in that when the bike is not running the clutch lever is dead.  You can, however, use it just like a normal clutch the same at the Rekluse z start pro.  Is does seem to add a little flywheel effect to tame the motor.  The bike rarely stalls and makes the KX, in my opinion, a much better trail machine.  

 

The initial set up is tricky at first but they walked me through step by step.  Haven't had to adjust it in the last 50 hours.  

 

IMO it is a very good alternative to Rekluse. 

Edited by tt81621

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Would I be able to do this on a 99?  I just want a small light up front.  Nothing really powerful, just an option for a little light in dark spots/night would be helpful.

Yep, it should have a Powerjet carb. Just find the voltage regulator, I think its by the airbox or under the seat on your year.

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Yep, it should have a Powerjet carb. Just find the voltage regulator, I think its by the airbox or under the seat on your year.

 

 

Then I can tap into the white with red tracer?  I'm assuming ground the light or what not somewhere on the frame?

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Im pretty sure it is still a white wire with a red tracer on your bike. You can run it to a toggle switch so it can be turned off and then to the light and taillight (if you want a taillight) ground both to the frame somewhere. Use LED bulbs for the best results. You will be surprised how bright it is.

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anybody offer a stabilizer that mounts down low and not on the top of the bar clamps for these bikes??  and has anybody adjusted sag on their rear suspension? is it worth the time? whats a good starting point if i do decide to do it? sorry guys, sooooo many questions i know i sound like a complete newb but i promise i've been riding over 20 years lol ... just want to get this bike right, i've got a good bit of time and money wrapped up in it... i really want to make sure the motor is as strong as it can be, i've only had port work done on a 125 and it took all my bottom end away is that the case with all port work? , never had any big bores, i'm wanting a high compression cool head but i'm just not sure what route i wanna go...  i don't have any unreal expectations i don't expect to be outrunning 450s just want a strong clean running engine 

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