Bike wont start need help

4 replies to this topic
  • mvoss

Posted June 22, 2002 - 09:52 PM


I hope this is ok to post here.

My son has a 1982 Yz 80. It's been running fine until yesterday. We were out for a ride, it was about 95 degrees out, and the bike started overheating. The coolant came out of the radiator overflow hose.

We shut it down and trucked it back to the house. I put new coolant in it but the bike wouldn't start. I then replaced the plug, still no go. I checked the carb and it was getting gas. I was also getting spark.
I then took the plug off, poored a little gas in and put the plug back on but still no go.

Any ideas as to what to check next. It's hard to tell if it's getting compression or not because before this the kick was also easy.


  • new_mulisha

Posted June 22, 2002 - 10:08 AM


if it never had much copression any way i think its time to tear it down and put a new top end in it and i bet then it will run fine (top end = piston, rings, wristpen, and gaskets)

the duke of eral

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Posted June 22, 2002 - 10:20 AM


if the top-end is outta spec it will contribute to some over-heating, so time for a freshen-up.

  • sirthumpalot

Posted June 22, 2002 - 03:30 PM


Since it ran fine before the overheat and not at all after the overheat I'm guessing you blew a head gasget or have a stuck ring or something. If you have a really blown gasget you can probably kick it over slowly with the radiator cap off and see bubbles. When I was little a friend had an overheat on an '84 YZ80 (blew the head gasget which resulted in all the coolant going out the overflow very quickly) that resulted in a small missing piece of the piston which caused the ring to get stuck and no compression. I'm guessing you've got something similar.

  • Guest_mxrider426_*

Posted June 22, 2002 - 08:55 PM


Man, my friend has a kx85 that is only a year or two old, and I have never seen a top end in as bad of condition. And the weired thing is that he said it was running fine. I guess it overheated somehow and the top of the piston and the inside of the cylinder head melted(you could see bubble marks on them), and the top of the piston smeared down over the ring covering part of it, and making it stuck. Then his piston skirt started to crack off, and I guess the pieces came up the ports because when he took his pipe off, and dumped it out, pieces of the piston fell out. And I guess he found out all of this was happening because he took the spark plug out and saw that there was a piece of his piston skirt jammed into it. Yep there was a peice of his piston shoved in his spark plug!!! :) :D :D And all the time it was like that, he said it was running fine. :D

And I know why this happened, it is a kx!! :D

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