KDXRIDER.NET

Ok, so I have a 2000 KDX 200 with the RB carb mods done and full fmf (clean silencer). When I first got the carb back I put it on and fine tuned the jetting but never got the upper range perfect.

My issue is I had the bottom to about 3/4 throttle is pretty good but there was a bog or stumble at 3/4 throttle. I don't tend to ride high in the rpm's but as of lately I have been a little more. I tried to lower the needle ( raise the clip) and that seemed to help the 3/4 bog but now I have a 1/4 bog instead. The needle I have installed is what RB sent back with the carb and I'm not sure what it is. I have a feeling I may need a new needle but am looking for any suggestions as to which one(s) to try. The carb is clean and the pilot seems to be about right and the plug chops look good. Any other thoughts would be appreciated. Right now the weather is back and forth between cold and warm so playing with the jetting is on hold until the temps get a little more stable.

Why are you messing with needle clips? With a 3/4 and up bog that's all main jet size. If below that was fine, the clip was most likely perfect in the original position. Go up one size on th main jet, put the needle back to where RB had it set, and report results. Above 3/4 throttle the needle is less and less in play, and the actual size of the main jet itself is what matters.

Sorry, I should have been more clear. The bog is AT 3/4 throttle. Past that is fine below that is fine. But when rolling on the throttle it will bog at 3/4 than straighten back out. Past 3/4 seems to be good now and before.

Weird.

Still, I say go up a size on the main and see what that does for you.

Tonight I pulled the carb and put the needle back in the middle, swapped out the 155 main to a 152 and the stumble seems to be much better but still has something going on. The bottom seems to be pretty good again but could use a little fine tunning with the air screw. I only put about 3 miles on it around the house so I guess we will see at the next ride how it's going to go.

I'm not sure why the main worked well past 3/4 throttle but it seemed to do the trick for now.

Thanks for the help. I'll up date later after I get some more time on it.

You went to a smaller main?

Since the first mention was a "stumble", I should think smaller would be appropriate. But then it's a "bog", in which case I would think larger. There's a pretty noticeable difference between a hollow lean bog and a rich blubbery stumble.

Slick_Nick wrote:Still, I say go up a size on the main and see what that does for you.

Oh ya I'd listen to slick

152 sounds pretty rich too me