KDXRIDER.NET

I have a new to me bike. I know no history on it. Drained fluids and replaced with fresh. Bike runs horrible. Seems from what I read jetting could be the issue. New plug and air filter. Seems to be bogged down in lower gears. One I hit top of 3rd gear it takes off like a rocket. Any help is appreciated. Getting a little discouraged. Has a 48 and 160 jet installed.

make sure you clean your carb 1st, but i'd bet it's jetted pig rich (looks like factory jets). Follow jetting guide in my sig and you'll get a beast bike in a couple hours

Thanks for the help.

Could also be a powervalve issue. If hung open it will kill low rpm power.

Reeds are another possibility, but usually if they are bad enough to kill low end power than starting will be very difficult.

Doesn't seem to have much power on the bottom. Once I get into 3rd gear it seems to pick up. Starts first kick. Runs like a beast through 4,5, and 6.

wouldn't hurt to know what we are talking about
im guessing a KDX but different models are prone to different issues

cleaning the carb, jetting it properly and doing a little maintenance is good practice on any bike you acquire

Sorry I guess I should have led with the goodies. I have a 2004 KDX200H. With a Pro Circuit Platinum 2, and a Pro Circuit 304 silencer. Other than that I know ( because I pulled the carb) I am running a 48 slow with a 160 main. No idea about the needle seems to all be pretty stock on the carb. I found it 5 turns out on the idle screw. toned it down to 1.5 and it seeems better. However it seems to be a little off yet. First and second dont come alive te way 3-6 do. I guess I need some different jets to dial it in.

Coming soon: 2004 kdx 200 for sale. Was really excited about this bike. Not anymore.

As with anything, learning your way around it will take some patience. Between the resources here and a service manual, there is absolutely nothing on a KDX that an average rider shouldn't be able troubleshoot and fix. Pull the carb, clean it (do not soak!), and follow the jetting guide found in the jets and needles section here. From the information you've given that would seem to be the best first steps. It wouldn't be a bad idea to pick up a service manual and study up a bit, so that you can familiarize yourself with what you're working on, IE air screw vs idle screw. If you aren't willing to take the time to troubleshoot this stuff, or even learn what's what, letting it go is probably not a bad choice.

Julien D wrote:As with anything, learning your way around it will take some patience. Between the resources here and a service manual, there is absolutely nothing on a KDX that an average rider shouldn't be able troubleshoot and fix. Pull the carb, clean it (do not soak!), and follow the jetting guide found in the jets and needles section here. From the information you've given that would seem to be the best first steps. It wouldn't be a bad idea to pick up a service manual and study up a bit, so that you can familiarize yourself with what you're working on, IE air screw vs idle screw. If you aren't willing to take the time to troubleshoot this stuff, or even learn what's what, letting it go is probably not a bad choice.

I have to empathize with Beavis, heh heheheheh. But seriously, I have done every possible thing I could do to try and make my bike run right. It was torn down to the crank, power valves, cleaned, new air filter, all new carb parts, almost every possible jetting combination, the list goes on––many of you have witnessed my troubles. My friend has a beat-up '95 with pig rich stock jetting that runs like a rocket, and just picked up a weathered 220 for a grand that runs beautifully.

The amount of time and money I dumped into this thing is sad, and I really believe that it's hit or miss buying used KDXes. If I were to do it over, I'd have unscrewed the circular power valve cover to check that it worked correctly, and I would have made sure the engine ran perfectly that day I went to look at it. It had a new top end, and that was why I was a bit forgiving in terms of its performance, but lesson learned. Basically what my KDX needs is an engine swap with one that actually works.

That's very strange. There aren't many engines that are more simplistic than these little 2 strokes. There just isn't much to them. If the fuel delivery, compression, ignition system, and power valves are all in working order, any performance issues should not be that difficult to track down. Of course, buying any used machine is going to be somewhat "hit and miss", but as a general rule a KDX is reliable as heck.

In the OPs case, it sounds like he really just needs to go through the jetting. Not that complicated. If problems persist afterward, then more troubleshooting is required.

I have been reading everything I can on the bike. Never had this much issue getting a printed manual. I work 60 plus hours a week and only get a few hours here and there to wrench. Even less to ride. Ive cleaned the carb and made some changes. Seems to get better but still isnt right. Wondering about power valve being funky. Young man I got it from said it had not seen much action in a year or so. It ran a little choppy on my test ride but i chocked it up to old fuel and being in the shed for too long. I understand the time and patience part. Im just disappointed that I cannot get in any trail time due to the mechanical state of the bike. Im not a carb person. I always chose to leave that to others for fear of screwing it up. I had always been told these are great woods bikes and I was excited to snag one. Frustrated with it at the moment.

the carb is easy to take apart and clean, hard to screw it up. the hardest is clean the jets really well.
Did you try the jetting guide?
start there and report what jets you end up with, the stock ones are far from optimal and will leave the bike run crappy.