Maintenance & Technical > KX250 / KX125
Getting the jet needle out of the throttle valve?
mustangfury:
I am having a problem with my bike bogging out in the mid range. It goes well up till about 1/4 throttle, boggs up to speed slowly from 1/4 to 3/4, then at 3/4 tears down the road like there is no tomorrow. I am also having an excess of oil that spits out the silencer when i wind it out. I think it might be the oil that isn't burning completely when the engine is bogging out. I have done one thing at a time trying for results but nothing has delivered yet. I have cleaned the air filter, checked compression, checked reed valves, and a few other things. The range of lacking performance seems to suggest it has to do with the jet needle being out of adjustment or the wrong size. I am going to try an move the clip either up or down on the jet needle but i can't seem to get the cable screw out of the throttle valve. The bike came with an fmf fatty and silencer. It also has Vforce Reed Valves. I run a 32:1 mixture which kaw. recommends using Bel Ray H1R.
My question is: how do you get the cable screw out of the throttle valve assembly? I tried to get some needle nose pliers in there but all it seems to want to do is tear up the screw.
Any suggestions on how to get it out besides drilling it or doing something that will require its replacement. Any suggestions on my general problem are welcome too.
Thanks
blueoval:
mustangfury, what part on this diagram are you having difficulty with?
http://www.mxsouth.com/keihin/keihin-complete-carburetors-diagram-parts-list-of-pwk33.htm
Hillclimb#42:
Finally a question that I get. The carb's upper chamber all unscrews, the little brass screw stays. You can release the clamps and turn the carb towards you a little, or pull the whole carb out. The whole top cap of the carb comes off and the slide will still be connected to the cable. The top cap should come off with your hand twisting it. Smash the spring that you will find between the slide and the cap, all the way compressed. hold the spring compressed to the lid of the carb. push the slide toward the cap for some cable slack and with a little jockeying the cable will come free of its notch.
If you look into the top of the slide, you will see a 6mm nut. That holds the needle in the slide. remove the nut and you will find the needle with a circlip stuck in one of 5 grooves. That clip is very hard to find if it shoots off there, so be careful. I lay it flat on a countertop and push the needle down while covering the clip with my hand, flip it over and snap the needle into the clip.
Moving the clip up one position will lean the mixture in mid range by lowering the needle into the hole, thereby restricting fuel flow a little bit.
When you put it back together, insert the needle and fasten with the 6mm nut, you have to again, smash the spring to the lid, then get the cable into its notch, then align the little plastic deal that keeps the cable from coming out of that notch. Make sure the throttle spring goes all the way down. Drop the slide back in there and screw the cap back on.
If this is the first time, you have been in the carb, it would be a good idea to pull it out all of the way and look it over for dirt and debris, or wear. Also good to note what jets are in it, and clip position, for future reference. I always snap the throttle a few times to make 100% sure that its working properly before starting it back up after messing with it, too.
mustangfury:
--- Quote from: blueoval on April 12, 2010, 05:22:47 AM ---mustangfury, what part on this diagram are you having difficulty with?
http://www.mxsouth.com/keihin/keihin-complete-carburetors-diagram-parts-list-of-pwk33.htm
--- End quote ---
I was refering to number 14 as the cable screw and was wondering how to grip it to get it out.
--- Quote from: Hillclimb#42 on April 12, 2010, 05:31:48 AM ---Finally a question that I get. The carb's upper chamber all unscrews, the little brass screw stays. You can release the clamps and turn the carb towards you a little, or pull the whole carb out. The whole top cap of the carb comes off and the slide will still be connected to the cable. The top cap should come off with your hand twisting it. Smash the spring that you will find between the slide and the cap, all the way compressed. hold the spring compressed to the lid of the carb. push the slide toward the cap for some cable slack and with a little jockeying the cable will come free of its notch.
If you look into the top of the slide, you will see a 6mm nut. That holds the needle in the slide. remove the nut and you will find the needle with a circlip stuck in one of 5 grooves. That clip is very hard to find if it shoots off there, so be careful. I lay it flat on a countertop and push the needle down while covering the clip with my hand, flip it over and snap the needle into the clip.
Moving the clip up one position will lean the mixture in mid range by lowering the needle into the hole, thereby restricting fuel flow a little bit.
When you put it back together, insert the needle and fasten with the 6mm nut, you have to again, smash the spring to the lid, then get the cable into its notch, then align the little plastic deal that keeps the cable from coming out of that notch. Make sure the throttle spring goes all the way down. Drop the slide back in there and screw the cap back on.
If this is the first time, you have been in the carb, it would be a good idea to pull it out all of the way and look it over for dirt and debris, or wear. Also good to note what jets are in it, and clip position, for future reference. I always snap the throttle a few times to make 100% sure that its working properly before starting it back up after messing with it, too.
--- End quote ---
I've had the carb apart several times for cleanings so i'm familiar with that aspect of it. That was the first thing i did in regards to the problem. I checked the float and made sure the float needle was working properly. I have gotten as far as getting the cable out of the assembly but the cable holder screw wont break loose and i think it is just because i cannot grip it well. There is no hex nut on my carb. According to diagrams i have looked at similar to the one posted by blueoval, it is just the cable holder that screws in. I don't know if i am using a different carb than yours. it is a pwk keihin carb.
thanks for the replies
Friar-Tuck:
Does this help?
You might drop some penetrating oil on it overnight. I have seen the 6mm stripped/rounded. There are a few options I can think of if it is stripped.
Needle nose vice grips.
If you have a dremmel and a small cutting burr you can carve across the the top and put a slot for a standard blade screwdriver.
If that doesn't get it a reverse drill bit might. The last resort for me would be an easy out in the hole the reverse drill bit made.
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