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Discussion Starter · #1 ·
need help with fuel gas mixture,i have a 2004 kx 125,this is my story so far,purchased bike,rode bike1/8 to 5/8 throttle bike spit and sputtered until it got on the main jet,rode bike hard trying to keep it reved up,oily drool coming from tail pipe, my guess bike running rich,so i changed packing in silencer figured it would be oil soaked it was, checked compression 175 psi, that sounded ok,replaced stock main jet420 with 410,whent down one size on pilot to 37.5 from a 40,needle clip second from top,air screw 1 1/2 turns out,completetly cleaned carb,spent 6 hours it was dirty,took bike for test run at night, ran fine,3 days later me and my son go riding,hes on a cr 125,ol dad gonna cut him today, crank bike up 1st kick starts right up,100 yards from truck bike cuts out,cant get it cranked up,pushed kawa back to truck,kick and kick no luck,pulled spark plug very blackand wet,changed spark plug 3 times would not crank,checked ol trusty manual under trouble shooting, it said to crack throttle wide open 1st try cranked right up, had to clutch and rev all day,bike started all day with cracked wide open throttle,oil drool still there spit and sputtered all day threw the entire powerband,float bowl overfill leaking from time to time all day too,but not all the time, atleast i did get to ride with my kid all day and have fun, manual says starter plunger stuck open under every fuel/air mixtuer incorrect what is this? could it be the kips or reed valves? any suggestions please
 

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Discussion Starter · #2 ·
well ive done a few checks,took carb off again cleaned,adjusted float height to .374 close as i could,it was off,done float valve to needle seat check with carb off used penetrant, needle seat did not leak,replaced oring on outside dia. of needle seat,checked reeds looked ok,cleaned air filter,and spark plug,pressure washed gas tank let it dry and washed out with gas,blew out all lines on carb vents.installed new fuel line and inline fuel filter,petcock strainer cleaned also,hopefully this bike will run ok today,if it doesnt gonna have to take it to shop,dont know what else to do,,,,,,,,
 

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What oil ratio are you mixing at ? How much are you loading the engine ? Are you woods riding ? Are you play riding in generall with more relaxed engine rpms? This will tell us what carb circut is running rich. I suggest mixing at 40:1. If you're plug is still black and wet, you are simply jetted too rich...

(PS please add some periods in your post, so I don't get out of breath reading your issues) :)
 

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Discussion Starter · #4 ·
jinxed again

mostly play riding,some trails, some track, mostly following my son,some where between novice and intermediate,mix ratio 32 to 1,tried to start bike today, opened petcock, i got clear gas line,holding level in gas line,tried to start nothing,loosened boots to carb rotated a little bit, removed drain cap from bottom bowl checking to see if iam getting gas,,guess what no gas,removed bottom bowl with fuel line stiil connected still no gas,tap float alittle bit it drops and i get gas,i give up,bottom bowl on float sticks, bottom bowl off gas runs free,guess it just wasnt meant to be,man versus carb and carb wins,2 choices now buy new parts and rebuild or buy new carb
 

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Sounds like a bad needle and seat.

Moose sells a rebuild kit that has all parts and gaskets with the exception of the float for around $30.
The OEM needle and seat is over $35.00

Mix fuel at 40:1 and use a good synthetic oil like Amsoil.

Rebuild carb
Install new plug

The first ride after the above repairs run the bike at WOT thru as many gears as possible then immediately pull the plug and check the color.

This will give an accurate "reading" on how the bike is running (rich-dark-black/lean-light-white)

If jetted correct the plug should "read" golden brown
 

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Bad needle and seat? Perhaps you are referring to the float needle valve?
But if that was bad the gas would not stop flowing. Doesn't seem you paid very close attention to what he typed.

The guy who has the problem ascertained quite well on his own, but I dont think he knows where to go from there.

He did not provide pictures or even tell us what kind of carb it is. Going by main jet size I'll guess Mikuni and of the TMX variety cause of 2004.

Has he looked at a parts diagram for the carb? Who knows? Probably doesn't matter he doesnt sound like a complete newb.
http://www.sudco.com/Diagrams323728/exptmx.gif

My guess, and this is only a guess, as usual, this is a Mikuni style float setup and the floats or the float needle valve tangs were installed upside down or some kind of bad assembly/adjustment or interaction between the two. He said he checked the needle valve and adjusted the float height. Now he has no gas. Well, ask yourself,"what changed?".

I experienced similar situations on Mikuni TM when trying to set the float level. Floats set wrong can equal no gas or gas flooding out the bowl overflow.
 

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Discussion Starter · #8 ·
the carb is a mikuni tmx 38 x. i do believe that the tang on the float, that has to be adjusted should be straight. it is kinda curved from repeated adjustments.this is most likely causing the needle float valve to stick in the seat.but i did get the needle float valve to seat.(manually)the pointed section actually looks like it is made of rubber, and has no indications of being worn.the o-ring on the seat was hard and brittle,and was replaced.every time i put the bowl on it is causing the float to not be able to move,could the float plate be worn or could it be dropping off its fit, or causing the float to stay open or stay close.i think the best thing is to buy the rebuild kit from moose and get a new float and float plate and start over.
 

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Discussion Starter · #9 ·
i do have a manual, and was looking at kawasaki parts list and they are actually showing to different float plates for this bike, i dont know really which one to order, one cost 16.00 and the other cost 3.00, maybe the previous owner put the wrong float plate in.nd4speed your guessing is pretty darn good, iam begining to believe that the float plate is causing problems also.any input would be great,thanks guys
 

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well the bike ran and you rode it, you played with the carb, and now it does not start.

I have never worked on a TMX carb.

Ok the float height adjust tang in the middle that rides on the float needle valve can become curved. I have seen and done that. Straighten it the best you can but really it should not be too much of an issue. But ,like you said, the tangs are usually straight (all 3 of them).


Also you can test the action of the tang and needle valve (even with gas on if you want to make a mess). I seem to remember having the bent adjustment tang feel like it was catching on the needle valve plunger. Action felt notched and not smooth. I did not like so i straightened it.(actuall it may have ended up kinda S shaped)

I hang the carb off the side of bike or lightly in intake boot, hookup gas line, turn on gas, wait till it stops flowing, turn off gas, crack open main jet cap on bottom and drain into something to check how much gas went into the bowl.


I did this last summer with a 38mm TM cause the carb boot i used puts the carb at a forward tilting angle. Carb looked clean and hardly used. Found the float needle valve was bad. Put in good valve. Now over adjusted and no gas, ect You have to play with it sometimes and it is trial and error to me because i can't measure float level with the bowl on. Only other way is to know how much gas should be in the bowl, but i dont think anyone tells you what that should be.
 

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Discussion Starter · #11 ·
i have been away for awhile,(working)i told myself that i could fix this carb without buying any parts.3 tangs on the carb,one holding the float needle valve.and one each holding the float.the left side float was touching the bottom bowl causing the float to stick.i tweaked the tang. and done a blow test,with the carb in the correct up right position(with the drain plug removed)free flowing threw the carb,turn the carb upside down and blew threw the fuel hose line and the float needle valve would not come off the seat.i installed the carb,turned air screw out 1 1/2 turns,cranked the bike up and played with the idle screw,and had total control of the idle,i was making it idle high and low,everything working good,i did not ride the bike and check the powerband it was to late at night,but the bike is idleing fine,thanks alot guys
 
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