KDXRIDER.NET

Hit me up about those 125 front end goodies, please. I've got an '05 KX 125 frame and I'm just starting to accumulate parts for my build.

sean-svm wrote:No the airbox fit right up. I'm a little concerned though, I found some dirt and junk in the venturi of the carb. I think I need to have a ring made to fill up a little space KX carb is quite a bit larger than the KDX.

I ran into the same problem with my '01 KX125/'00 KDX220R conversion. The difference between the KDX carb and KX airbox is huge...like several mm's....there was no way I could clamp it down and not expect it to kink. I ended up turning the OD of the intake side of my stock KDX carb down smooth (to remove the "lips") and heat shrunk a custom stainless ring onto the carb to make up the difference, worked perfectly. I can post pics and a some dimensions if you are interested.

Beautiful bike BTW, looks 110% professional. I hope mine looks 1/2 as nice after I "prove" it out and strip it back down for repainting. It's a pretty ratty looking prototype right now.

That'd be great if you could post up some pics and dimensions!

I'm looking to build a hybrid soon....Hopefully an '03 model as I already have a front end and a manual for it. I'd really like to see your fix for the airbox boot. Thanks in advance!

man thats a sweet bike sean-svm...im workin on my 99 125 and 00 KDX....hey UFS207, some pics of the air box line up of that 01 would really be a plus...and would help me out tremendously.

Maybe I need to look at mine more closely, but my KX airbox boot seemd to work fine with my KDX200 carb. I did buy it separately from the frame, so maybe it is off a 250. Will this make a difference?

The diameters of the boot and carb are pretty significant but I've been checking after my last couple of rides and the inlet of the carb has been clean. I do have to screw the clamp for the airboot all the way until it bottoms out but it appears to be sealing.

I agree. I had a terrible time getting the boot to shrink down small enough to seal on the carb. It was winter and the parts were all 20 degrees. I figured it would mount better in the spring. It does, but I too had to really crank down on the clamp. I have a KX125 2003 and a KDX220 2004. Getting the boot to fit was one of the hardest parts of the conversion. I have ridden in 1 hare scramble and it is still tight. However It's going to have to be checked before every ride. Can't afford to have it pop off before or during a ride.

rdsrf wrote:That'd be great if you could post up some pics and dimensions!

Haven't forgot about this, will take some pics and measurements this friday when I have the time to wheel the bike out and pull the subframe again.

Had a thought in the meantime though: you could maybe find a piece of heater hose (aka radiator hose) that was the right diameter to fit over the KDX carb's intake, cut a 1/4" or so off the end and tighten the airbox boot down over that.

Very nice job. Couple of questions; what model/application are your oversize tank and pipe? I'm starting on an 03 kx125 chassis/98 kdx200 engine build, so thinking the same would work for me? Also curious about some of the cooling hose connections that show up in the pics. Are they adapters piecing modified hoses together? Thanks in advance!

The tank is an IMS for a 2005 KX 125, it fit up perfect no modifications were needed. The pipe is a FMF gnarly for a 2003 KDX, again no modifications were needed there either. I can't say if they would work for you though. From my research on hybrids I did on this site, the 2003 frame is different from the 2005's. It looked like pipes and tanks had to be modified for those bikes. To modify the radiator hoses I went to Lowes and picked up some brass fittings from the plumbing dept., then I cut the hoses in a straight section and then twisted them to get the angles I needed.

I could be wrong but I though that the frames changed from 2002 to 2003.

I had hoses for both the KDX and KX and I just grabbed what looked like ti would fit and nearly all of them did. I had to shorten one hose but didn't have to use any fittings or splices.

I also have an IMS tank. It is tight underneath but seems to clear everything. The headstay bracket like the one above it probably the only way to get it to fit. I did mine a different way and it hit the tank. Now I will have to change it to like the one above.

I used a KDX PC pipe and a KX250 silencer. Everything lined up good.

What year kx250 silencer fits best?

Tedh98 wrote:What year kx250 silencer fits best?

I would say the year that your frame is. All KX250's from 2003 and later were the same so any of those years would work. I wouldn't try to fit a silencer from a 2002 or earlier on a 2003 and later bike. That was what I was gettign at about the engineers using the same dimensions and stuff over and over. The KDX PC pipe goes right down between the KX frame and airbox just like the KX pipe. The KDX pipe stopped for the silencer at the exact same place that the KX pipe would. A lot of things just seem to work too nicely to be by chance. If you put a KDX motor in another brand you would have to REALLY work, cut, fab and weld a lot more. It seems that the 2003 and later KX's were closer in a lot of these regards than the older KX's. I guess Kaw finally realized how sweet the KDX was and modeled their later KX's after them.

Looking forward to those photos!

Wow! what a machine! I am wanting to build me one of these - in fact exactly like this. Any further ride reports there?
And tell me, if I want to build the ultimate woods weapon would I need to go to KX250F forks also, what is the reason for doing that? And lastly, how do you like the subtanks?

I've got quite a bit of ride time and races on the bike and its finally coming together. I've made alot of changes inside the forks: different fork and ICS springs, different shim stacks and found a set up that is working well right now. I can ride through some pretty rough stuff that before would bounce me all around. Its plush and good in the woods but SUCKS for moto. I used the 250F forks b/c I had bought a set to put on my old KDX before the KX chassis fell into my lap. I'm sure the stock KX 125 (open chamber cartridge) would have worked well, the KTM XCW's use a similar style, but I had the KXF's so I went with them.
The sub tanks are working out well. I find myself running them either full open or full closed depending on the conditions and they are a nice addition to my set up. I have had to replace the main valve once already after a good get off but other than that no complaints.

hey sean-svm....do you know how new that gnarly pipe is?...i have a 2000 model gnarly and it looks alot different than yours...im thinking that they might have changed the design over the years...and that maybe a newer gnarly will fit alot better than the older ones.

jc7622 wrote:

Tedh98 wrote:What year kx250 silencer fits best?

I would say the year that your frame is. All KX250's from 2003 and later were the same so any of those years would work. I wouldn't try to fit a silencer from a 2002 or earlier on a 2003 and later bike. That was what I was gettign at about the engineers using the same dimensions and stuff over and over. The KDX PC pipe goes right down between the KX frame and airbox just like the KX pipe. The KDX pipe stopped for the silencer at the exact same place that the KX pipe would. A lot of things just seem to work too nicely to be by chance. If you put a KDX motor in another brand you would have to REALLY work, cut, fab and weld a lot more. It seems that the 2003 and later KX's were closer in a lot of these regards than the older KX's. I guess Kaw finally realized how sweet the KDX was and modeled their later KX's after them.

I finally found an '05 kx 250 silencer for my '04 frame and you are right, it fits perfectly. Thanks for that advice.

bulabula09 wrote:hey sean-svm....do you know how new that gnarly pipe is?...i have a 2000 model gnarly and it looks alot different than yours...im thinking that they might have changed the design over the years...and that maybe a newer gnarly will fit alot better than the older ones.

I'm not really sure. I bought it new this winter when I did the build. 088-020057 is the number on the upper mount flange.

YOUR BIKE IS SICK DUDE!!!