Help needed for 2-stroke tuning - 2001 KTM 200 EXC

I bought a 2001 KTM 200 EXC that wasn't running due to a cracked cylinder.  I ended up completely rebuilding it from the ground up.  It is all back together now, but I have no idea how to tune a 2-stroke.  It was completely stock and the carb was stock with the carb set-up as listed below.  But since I never heard it run, I have no idea how good it was running.


Current set-up:

   - 212cc big bore kit

   - powervalve & head porting

   - FMF Gnarly & Turbine exhaust

   - Stock carb (180 MJ, 42 PJ, NOZG)

   - 93 octane

   - 2,000' altitude


I set it up as:  180 main, 42 pilot 1 1/2 turns, and NOZG 3rd.  It started right up, but I had to turn the idle screw in almost all the way to get it to keep running, and the idle mixture didn't seem to make any difference until I screwed it in almost all the way - maybe 1/4 turn from bottoming out and then the idle started to decrease. A short test run had it running really flat after 1/2 throttle. Then readjusted the powervalve so that it opened a little later. Another test hop and it was a little better, but still flat from 1/2 on - never really revving out.

A couple of things I noticed:
1. There is an occasional popping on decel - kinda like a quiet back-fire or single cackles. On my 4-stroke, I would take that as an indication of possibly being too lean. Is it the same with a 2-stroke?
2. As I was trying to run the gas out of the carb bowl, (fuel turned off, running) once it started to run out of gas, the idle picked way up. Would this mean that I'm running too rich in the idle circuit?

I also had been running a mix of 32:1 for initial break-in. I've since changed to 40:1 but haven't had a chance to see if it makes any difference.

And, finally, I have an assortment of jets and needles now to work with: 170 through 190 MJ, 38 through 55 PJ, NOZF, NOZG, NOZH.

Any suggestions on where to go from here?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Similar Content

    • By Sammy_1101
      Hi Guys,
      So I recently bought a 1997 XR400. I've done some research into getting more power through some basic mods and rejetting the carbs. Though all of the ones I've found have been for post 98 XR400s so the stock carb set up is a lot different. Usually people are opening up the airbox, exhaust ect. ect. and Jetting their carbs up to 160/162 for mains around 60 ish (I think) for the pilot. However for the 97 model this is close to stock for the jets.
      So essentially what Im asking (Just to cut to the chase ) Has anyone got a 96/97 (maybe 98, not sure) XR400 and has done these similar mods, and what sort of jetting have to done as a result.
      Thanks in advanced, also its my first post so apologies if I havent done everything correctly.
    • By Jturn
      38MM Cast SmartCarb. Purchased a couple years ago for a yz250. Don't have the bike anymore, and it has been sitting around for about a year. Used, but in fine working condition. You can also purchase a different needle for different bikes, as well as rebuild kits from their website.
      Asking $250 shipped to continental United States. I can arrange other shipping options at the buyers expense.
    • By faizakhtar125
      Hey guys I just bought a bike last night. So the seller said the bike will turn on but then die. We didn't try it because it was really late at night and it was raining (seat was wet). But he said if you bump start it, it will turn on and ride. So what do you think the problem is? I just want to make sure it runs... I probably won't be able to bump start it till Saturday (rain)... It's a four stroke, and I know absolutely nothing about them. Thanks.
    • By knotduke08
      I know this topic has been discussed in the past, but I have not found any options available for the new 2018 bikes. I live and work for a new Beta Dealer (Auburn Extreme Powersports) in California, and we are having a difficult time mapping the RR-S bikes for full FMF exhausts. We have tried contacting Beta Support several times for this issue to no avail, and we typically are given the runaround when transferring to techs and secretaries. From what we can gather, the FMF flash is designed for the RR bikes, but not the street-legal counterparts. Every time we try to install the FMF map onto an RR-S errors occur, and the programmer screen goes virtually blank. We have heard through the grapevine that some are using the RR maps on the RR-S with success, but we have yet to try it, even on our own bikes for fear that it will permanently erase or damage the CDI. Any and all help or suggestions regarding this topic would surely be appreciated! Thanks, Ben.