Maintenance & Technical > KX500 Original

jetting maybe?

(1/3) > >>

HK_Shawn:
help!
i have a 92 kx 500 that i just picked up. when purchased the bike wouldnt hit power band and chugged down low. i tested compression and it was at 85psi. i redid the top end and while it was apart i cleaned the carb and checked kips function. now that the bike is back together its still doing the funky rev thing, its almost like its hitting a rev limiter when the main is supposed to open. the crazy thing is when i shut off the gas and let the bike run to eat up the fuel in the carb it cleans up and revs right before it runs out of gas. heres what the carb is set at:
main 168
pilot 60
#3 clip
1.5 turns a/f
40:1 mixture
while it was apart i checked float level

bike has stock pipe and pro circuit can
no lid on the air box and an K&N filter

am i missing something?

HK_Shawn:
forgot to mention this is at sea level

Hillclimb#42:
I would be looking at the reeds and main jet. Main jet would be easy to check for debris without much disassembly. I was told that the reeds only affect bottom end before, but from experience, I found that with broken petals the bike started, but would not rev.  More throttle equaled more bog. I'm confused a little that you say that you shut off the gas to run it out of gas and are surprised it revs before it dies. Not sure about that method helping with longevity either.
  You should always know if it starts revving off of idle for no reason, the carb is out of fuel and the air/fuel mixture is leaning out causing a rev. Sometimes you forget to turn the gas on after a break, or just plain run out of gas, even a clogged petcock with a slow flow acts like that. It can Braaaaaaaaap, and take off like a rocket with just a little throttle when its almost out of gas. Scary on a 500.
  No power at the top-end is not related to that. You called it probably, when you said it happens when the main should open. I blow through main jets onto a piece of paper to analyze what got in there and how.  Is it smoking like a mosquito fogger when this happens? If so, could be crank seals. Good Luck.

HK_Shawn:
the reeds are brand new vforce 2's, i put them in with the new top end.
i ran it out of gas because i was going to pull the carb, thats when i noticed the improvement under lean condition.
the main jet is clean, ive taken the carb apart about 10 times now and check it every time.
ive adjusted the needle from one end to the other and it doesnt effect the way it runs.
i also drained the crank case to see if the crank seal was sucking but that didnt make it run better either.

is there a chance that the ignition is weak and it will only fire when lean?

thanks for your help and keep the ideas coming.

Hillclimb#42:
 The weak spark issue has come up several times, but I have never had a spark issue, so I am either lucky or they are rare. Other guys had troubles with low rpm spark, but their weak spark condition was helped by revs. Have you checked the pipe and silencer chambers to be sure that they are all clear? If the gas is on and you lean it way over gas comes out, then when you stand it up gas stops pouring out of the overflow, right?

You might try to add more description, too. I get that its not revving out. Is it revving there quickly? Is it loading up at an idle? Its fresh fuel too? No way its contaminated? Just ideas, not trying to be insulting. I remember BDI or somebody having a choke valve that broke or something that essentially kept the choke on.

Good choice on the reeds. They work well.

Navigation

[0] Message Index

[#] Next page