stalling problem

[87500rider]

i have a 1986 kx500...i start it and it idles fine...then wen i ride it it runs fine for about 5 minutes then bogs and shut off as im riding...has anyone else had this problem...any tips on how to fix it?

[Friar-Tuck]

 Where do we start....    What have you tried so far, and when did this start.  Did the condition start gradually or just one day it started and continues .
  I'm pretty lazy, so the easy/simple things get tried first... Fresh fuel,plug,airfilter (clean),etc. 
 
 Fuel or Ignition   "bogs and shut off as I'm riding..."   first thought is fuel... (starts & Idles)
 
 If the tank vent is not working properly, it will create a vacuum and not let fuel in your carb. (same for carb vents & overflow)
 If the in-tank filter (fuel valve inlet pipe) is plugged/restricted it will restrict fuel flow, or the valve itself has become corroded or sediment has found its way in the valve.
 If the float is not working properly or set too low you can run carb bowl dry, or the viton tip of the needle is boogered (possibly with age or meth/alcohol fuel content)
 How does the fuel line look, is it getting plugged,restricted..

If the coil or cdi has a bad wire or winding, a few moments running may cause enough heat to open the circuit, along the same lines, Then again the plug may be bad, or the plug cap or the wire.

There is some troubleshooting stuff in the gallery
 Pg.1)  http://www.kxriders.com/coppermine/displayimage.php?album=lastup&cat=1&pos=30
 Pg.2)  http://www.kxriders.com/coppermine/displayimage.php?album=lastup&cat=1&pos=21
 Pg.3)  http://www.kxriders.com/coppermine/displayimage.php?album=lastup&cat=1&pos=22
 Pg.4)  http://www.kxriders.com/coppermine/displayimage.php?album=lastup&cat=1&pos=23
    Etc...
  Let us know what you tried and how it went.
  Tuck\o/

[87500rider]

i put fresh gas in it and it ran better and i cleaned the carb....i will chech the tank filter tommorow and let u know how it goes...thanks

[Friar-Tuck]

 I'm sorry I can't give you anything more definitive '87,
  Trouble shooting is more or less about patience an working through the systems one at a time in some kind of order.
 Verifying that fuel is available at the carb is where I would start.

  Maybe drain the tank partially by the fuel valve. that would rule out the the tank,vent and valve.
  Tuck\o/   

[87500rider]

i fooled arouned with it today and i dont think it has anything to do with the fuel i think its electrical....cause i let it idle and all of a sudden it shut off like i was hitting the kill switch....any ideas?

[Friar-Tuck]

 Well,
 If you think the fuel system is good, it's on to electrics.

  Since the bike starts & idles, or runs for 5 min or so, And then just dies.
I think I would check all the wiring for chafing, clean & lube the connections w/ dielectric grease .
  Make sure all the grounds are clean, corrosion may be killing your bike after it gets too hot to carry the juice...
  Remove the kill button and rule that out.   
  Swap the plug and check the cap and wire.  Maybe cut a small piece off each end and re-attach the cap &  coil end.
  (Ohm out the wire and wiggle it while connected to your meter to look for a possible break.)
That's the easy stuff I think...

 Next would be to remove the coil and start checking that.
    An ohm meter won't detect a layered short or a breakdown in the insulation or a wire under high voltage, or
that shorts due to heat.
  Do you have a multimeter, and have you used one?
 set your mmv meter to x1 ohm
between the coil terminals .

 primary should be 1.0 ohm +/- 15%

secondary (spark plug lead and ground terminal)  5.9 k ohms +/- 15%

 Lets see how all that checks out.
  The cdi has a warning not to check it with too high a voltage multimeter or we could damage it....

 Tuck\o/

[BDI]

Check all coils. check them cold then heat them with a hair dryer and check again. Coils are nitoriouse for working when they are cold but quit when they get hot. Very typical problem.

[Friar-Tuck]

  Thanks BDI,!
 I never thought of the Hairdryer!
  \o/

[Polar-Bus]

i have a 1986 kx500...i start it and it idles fine...then wen i ride it it runs fine for about 5 minutes then bogs and shut off as im riding...has anyone else had this problem...any tips on how to fix it?

Why does everyone always suspect bad electrical components right off the bat ? Yea, the do ocassionally go bad, but the other 90% of the time it's fuel and or worn top end related. Check the simplist things first, like consistant adequate fuel flow. Need more specific details about how the bike starts runs, dies then restarts... is your plug wet after it dies ?

Guys, in all honesty i've owned 9 dirt bikes, and 6 street bikes, and 5 snowmobiles, and out of all these I had 1 bad stator on my '84 KX125, one bad CDI on my '81 Blizzard snowmobile, and those wer both on 20+ year old vehicles...

[BDI]

i have a 1986 kx500...i start it and it idles fine...then wen i ride it it runs fine for about 5 minutes then bogs and shut off as im riding...has anyone else had this problem...any tips on how to fix it?

Why does everyone always suspect bad electrical components right off the bat ? Yea, the do ocassionally go bad, but the other 90% of the time it's fuel and or worn top end related. Check the simplist things first, like consistant adequate fuel flow. Need more specific details about how the bike starts runs, dies then restarts... is your plug wet after it dies ?

Guys, in all honesty i've owned 9 dirt bikes, and 6 street bikes, and 5 snowmobiles, and out of all these I had 1 bad stator on my '84 KX125, one bad CDI on my '81 Blizzard snowmobile, and those wer both on 20+ year old vehicles...

Your right a couple of jack asses like us probably shouldn't even waste are time trying to help.

[Polar-Bus]

i have a 1986 kx500...i start it and it idles fine...then wen i ride it it runs fine for about 5 minutes then bogs and shut off as im riding...has anyone else had this problem...any tips on how to fix it?

Why does everyone always suspect bad electrical components right off the bat ? Yea, the do ocassionally go bad, but the other 90% of the time it's fuel and or worn top end related. Check the simplist things first, like consistant adequate fuel flow. Need more specific details about how the bike starts runs, dies then restarts... is your plug wet after it dies ?

Guys, in all honesty i've owned 9 dirt bikes, and 6 street bikes, and 5 snowmobiles, and out of all these I had 1 bad stator on my '84 KX125, one bad CDI on my '81 Blizzard snowmobile, and those wer both on 20+ year old vehicles...

Your right a couple of jack asses like us probably shouldn't even waste are time trying to help.

BDI, did I at any point call anyone a "jackass" for thier input  ? Why the attitude ? More and more posts I read about "my bike runs bad" equates to an immediate  "check the  coil/igniter/CDI" reply , and many times, the necessary facts are vague. Many new members don't have the necessary tools and experience to systematically diagnose electronics.  Diagnosing internet engine issues is challenging, espacially when you are not face to face looking and listening at the issue, let alone a post that many times calls out vague details. I respect ALL opinions, i'm simply trying to state to check the basics first not last to attempt to save a member from spending unnecessary money on components that are good to begin with.

[BDI]

Checking electronics is free. Unless you have to buy a multi meter and book. These are things most people should have. I would never suggest someone would just start buying parts, I'm a real mechanic not a parts changer. His description fits the bill for a bad pulse coil, this can be dignoseed for free in a half hour and then we could move on to the next possible prob. sorry for the jack ass thing polar but if some one tells me their tire is flat I'm not going to suggest they tighten their axle nut. I'm going to go with the prob that most closely fits the symtoms first and then move on.

[Friar-Tuck]

 Yikes!!
 BDI is on the mend, and actually, He' has been a really good dog lately.. (I think he's getting better.. )

   Polar, What happens I think,  is most guys who hang around and try to help just flat get discouraged with having to always be shooting in the dark.  How many other sites would have been yelling  !RTFM  That's what keeps us from becoming just another bike site.
 It's hard to pull the skill level of an owner out without making them feel like they have just been in the principals office. 
    You guys would be amazed at all the issues that have been solved through the site without having to go to a shop.
My worst fear is more guys will stop attempting to chime in, take a look back and see how usernames check in a day and don't post.   
We all have different approaches to troubleshooting.. Please keep throwing ideas out there!!
  Tuck \o/

[Hillclimb#42]

Yeah, I agree tuck. Both about the site and BDI has been pretty tame lately, he must be getting better. happy to hear from you, BDI. Thats good to have everyone say what they think, so the bike owner can get some new light shed on it. Lots of threads like this one, guys are thinking its definately not this new part or it can't be what I just cleaned or rebuilt, but the fact is, if it was easy, they would never post the question. Besides, I thought everyone always said "Crank Seals", now its "Compression" , or "Electrical" thats always last on the list for everyone. Mostly  because they don't typically just quit one day, and also because the expense. Coils and stators do go bad and are not simple tests, especially if the condition is not constant, or prevents the bike from starting sometimes. Great tip with the hair dryer. No reason to beat your head on the wall, if someone can point you to the correct repair. Its not a race or a score on this, we just want to diagnose it too. I would appreciate everyone finishing off the threads with the thing that wound up being the correct repair, too. Sometimes we get it fixed and go ride it, then forget to post what fixed it. That would be the best conclusion for these kind of threads, make sure the answer is posted....good luck

[don46]

Checking electronics is free. Unless you have to buy a multi meter and book. These are things most people should have. I would never suggest someone would just start buying parts, I'm a real mechanic not a parts changer. His description fits the bill for a bad puls coil, this can be dignoseed for free in a half hour and then we could move on to the next possible prob. sorry for the jack ass thing polar but if some one tells me their tire is flat I'm not going to suggest they tighten their axle nut. I'm going to go with the prob that most closely fits the symtoms first and then move on.

Hey Brian, thanks for the tip, you know I hate changing flats, next time I'm going to tighten my axle nut , on to a serious note, I typically don't respond to questions like this for two reasons, the person already has in their mind what the problem is and you can't change his mind or you get 30 posts on what it could be. Like polar I've had sleds bike and whatever and when I read the post my first inclination was the same as Brians, Electrical, the description fits the bill to a tee, works when cold and as soon as it warms up bam, no more spark. If it was a top end it wouldn't run fine for 5 minutes then go south, usually a weak top end makes it hard to start. So the question was posed whay jump to electrical, well because the described symptons are electrical. I can tell you I've owned more than 9 dirt bikes and 5 snowmobiles and I've had electrical issues, they are more common than you would believe and I would suspect that it is more than 10% of the time given the symptons described.

to the original poster, do you know someone the has a k5, no matter the year, you can swap ignitions and try it out, an 86-04 ignition will work, you just need all of it.

good luck

The axle nut should go in riding tips, I like it, two thumbs up
At the end of the day we are all here to help each other out, so to discount one suggestion because you have never had the issue doesn't mean it doesn't exist.