Recommended jets for 92 KDX 200

[iamthecowboy]

Hello all, I am new to the KDX forum and just got a 92 KDX 200 in excellent condition. Problem is, I don't know anything about them. Could someone please let me know what the recommended jetting is with an opened up airbox? Also, it has an aftermarket pipe without silencer and I need a stock one, will a pipe off a newer bike work? Any info is good info.
Thanks guys! :nod:

 

[paab]

No, you need a pipe from 90-94. The stock one is super quiet which is great IMO. I just went through the whole jetting baseline process, and here's what I found to work: (I hope I'm remembering this accurately)

Main 148
Pilot 38
needle CGK in the fourth position
Air screw 1 and 7/8th turn out

I may try the 35 pilot this summer. Overall, this improved performance everywhere, but especially down low.

I would work your way leaner slowly so as not to blow anything up. It's worth it in the end to spend time getting this dialed in.

 

[iamthecowboy]

Thanks, my other bike is a crf250x, and I know all about that bike, but this is going to be my spare that I will leave with my buddy in KY. I want to get it mostly dialed in before I take it down there.
- TheCowboy

 

[iamthecowboy]

I didn't have a 148 main, but I had a 150 and I didn't have a 38 Pilot, but I had a 40, so I removed the 155 main and 55 pilot and dropped the needle and the bike runs awesome. I opened up the airbox and cleaned the exhaust. I can't wait to take it on a real trail ride, just ripping around my yard just isn't enough. Thanks for the help!

 

[paab]

Get the CGK needle. It's really good. Glad you got it going in the right direction.

 

[iamthecowboy]

What is a CGK needle and where can I get one?

 

[paab]

It's a different needle taper/diameter from stock. Search it. There's a few threads on it. I got mine at Pat's Small Engine Parts online, but I don't see the carb stuff on their site anymore???

Looking at my notes, I see I also ended up at 150 main, 40 pilot.

 

[johnnymoto]

I have a 92 kdx 200 which I bought new and after 14 years of riding with a race here and there, it's still chugging along. I have only made a couple of mods, a pro circuit pipe and fmf ram valve and I also dropped from a b8es to a b7es plug and picked up a big gain in off the bottom snap. The basic short coming of the bike is the soft and mushy suspension which can be up dated with after market springs but mine is stock. She smokes a little but I have only cleaned the power valve once in 14 years. I know-shame, shame, shame. I deserve the flames but when I have time to clean it, I go ride instead. Invest in a shop manual also. It's not a ktm or a crf but it's the best little trail bike I have found in 40 years of riding. moto

 

[glad2ride]

If you want to retain the stock taper, go for an R1173N.

 

[jssport]

Read these:

http://www.frpoffroad.com/kdxposed/engineTips.aspx

http://justkdx.dirtrider.net/

 

[paab]

Wow! An update, I finally got the 38 pilot, dropped teh CGK needle to the second clip, and put in a 148 main and this motor is incredible. Smooth from bottom to top and it really pulls AND spins up quick. (90 bike, stock pipe, airbox opened up)

Plus, no more smoke or spooge!!!

 

[G. Gearloose]

It should because thats a killer needle for that vintage, but thats a really lean main, beware.

 

[paab]

150 is stock, so I don't think it's that lean. THe bike wouldn't rev out very well with the 150, I could feel the transition from the needle, which is spot on, to the 150 which was definitely rich.

Don't worry, I race a 125GP bike and jet it for maximum power each day. I can feel when it's getting lean by the loss of torque/quick rev character. I'm nowhere near that. I'm sure I'm 3 jets fatter than optimum, and it would take a few leaner to do any damage.

I haven't worked out a chart for this bike yet, but it feels fantastic and it's not detonating. temps in the 80s, humidity in the 50s, sea level-1,000 feet. If anyone has data on their jetting experiences, I'd love to see some for reference.

YMMV

 

[G. Gearloose]

paab you have a lot to learn too. 150 is stock because the airbox is so restrictive it chokes the carb at high rpms. Its no way to run a railroad. Open up the airbox lid if you havn't yet, and set the main right with some plug-chops, else you are thowing away power

 

[glad2ride]

The 148 sounds OK, but the 38 sounds way too lean.

 

[G. Gearloose]

38 is just perfect with a CGK needle.

Historically 148 is too lean for the 200/35mm, 148 is 220/33mm terratory

 

[paab]

Teach me ;)

I have opened the airbox. The jetting runs perfect at the moment. I've read up on this site and Jeff's, and I had a stuttering bike spitting raw fuel out the tailpipe, so I started working my wat towards this setup a little at a time.

It's making noticeably more power (revving more freely) than the 150 did, and it's not detonating. I still have the stock pipe for quietude.

Over the last five years I've learned a fair bit about jetting, winning an expert raodracing championship on a 125 GP bike. I opened that bike after every session, and learned to jet by feel.

I'll do another chop, but feel tells me that I'm in the ballpark for making power.

 

[G. Gearloose]

I concur, quiet is good.
Whats the width of the soot ring on the insulator after WOT, and the plug heat range?

 

[paab]

Plug is an 8.

I have the bike torn down for a shock/swingarm rebuild, so I can't do a fresh chop, but I looked at the plug anyway. My last ride was an hour and a half at the motoX track and the nose is chestnut brown pretty much all the way down. The wire has a nice clean burnback to 3/4 length. I'll swear that I'm still a tad rich, but right near the zone for making good power.

Other setup details:

I run boyesen 2 stage reeds, and I put a piece of fuel cell foam over the top of the open airbox to keep junk out. It's incredibly open cell and air flows nearly unrestricted through it. I used it in the rain on the roadracer (no airbox or filter) and it never required a jetting adjustment...

 

[G. Gearloose]

Plug observations like that are not indicative of the health of the main jet selection.

 

[paab]

I know, I'll do a chop with a fresh plug when I get it back together.