KDXRIDER.NET

Just purchased an '03 KDX 200. I have not owned a 2-stroke for 10+years so I'm a little green. I have read a lot of helpful information on this site but just want to double check if I'm understanding everything correctly. This is very low hour, completely bone stock bike. I have drained and replaced all the fluids, cleaned the carburetor and air filter. I replaced the pre-mix with fresh Golden Spectro mixed at the factory specified 32:1. This what the previous owner used and a bottle was included in the sale so I used it.

The bike ran very rich especially on the bottom and smoked and spooged quite heavily. In an effort to lean it up a little I open the air box up with some holes, removed the snorkel and dropped the needle 1 position. The air screw is only set at 1/2 turn out. If I go out more than that I get a pretty good bog off idle. These adjustments helped some in the mid-range and up but the bottom end is still blubbery. The carb has the stock jet configuration, 160 main, 48 pilot, R1174K needle which is now set in the 2nd position. I ordered a 155 main, 45 & 42 pilot to try out.

Now, to be clear that I am understanding this correctly: A rich condition is a fuel/air/jetting issue, not a fuel/oil ratio issue, correct? So in order to correct a rich condition I need to go down on the jetting and then fine tune with the air screw, correct?

Lastly, I have always used and had good results with Amsoil products. So, I purchased a bottle of Interceptor that they recommend to run at @ 50:1. I am a little leary of that and will most likely start off at 40:1. Any thoughts?

check my sig for how to.
seems you are on the right track with the mods and the jetting.
pick a ratio and jet for it. most use 1:40 and are happy with it.

My KDX has always been run on Amsoil at 40:1. Makes sure you have it filled up with the mix you plan on running and the ratio you want to use before you go through the jetting process. No sense in jetting it for 32:1 then switching to 40:1 later, you'd need to re-jet. 155-45 is a good starting point for most people. Many will end up going leaner than that, but seldom richer. Tuning the pilot jet and needle are pretty straightforward. The main requires plug chops. The link in scheckaet's signature above is an excellent resource. You just have to commit a half day to actually doing it, lol.

as for the "rich" comment
mixing your oil at 20-1 is rich
running a 175 main is also running right
(towing a brand new KTM with a 18 year old bike is priceless)

the term applies to both subjects

Gotcha! I think thats where I was getting a little confused, that the terms lean & rich apply to both the jetting(rich in fuel) and the mix(rich in oil). I drained what was left in the tank today and filled it up with 40:1 Amsoil mix and as soon as my jets get here I'm gonna get to it. Stopped by the dealership just today just to see if they had some jets in stock and of course they didn't, but they did offer to order the (2) jets for me for $23.00! Who pays those prices? I also pulled the drain plug from the stock silencer and drained a bunch of oil and crusty nastiness out of there. I was so surprised at how much came out that I took a picture of it. If I could figure out how I'd post it here... Thanks for your advice!