i just bought a kx 80 for $20 but it doesn't run. i pulled the pipe off and looked into the cylinder and the piston wasn't moving when i kicked it over so i thought the connecting rod or crank was broken but i took the jug off and the connecting rod isn't broken and i don't think the crank is and also the piston moves like normal with the jug off????? does anyone know what could be wrong with this??? the person i got it from said they took it to a dealer and they told him the bearings were bad in the bottom end. and this bike just had a new top end put on it. i need ideas????????????

 

I know that they are guaranteed to blow up on me.

 

its a major piece of chit. sell it!

 

If the piston moves with the cylinder off it should move with it on. If it needs crank bearings the you should be able to feel some play when you wiggle the end of the crank. Or you could feel it when you turn the crank by hand.

 

its worth 20 bucks, use the parts towards a fiddy and youll have a kick *** suspension!

 

ya i didn't get hurt on the deal since the kid i got it from bought it off ebay for $510 i'm not complaining. i was out messin with it and now the piston won't move so like sometimes it will and sometimes it won't

 

Can you spin the crank by hand with the jug off? If so what does it feel like? If it feels like there is dirt in the bearings or it catches then you need to do crank bearings and seals.

 

i haven't tried to spin the crank by hand i just push the kick start down if it was bearings why wouldn't it grab all the time????

 

If it's just the kickstart not grabbing then that's no big deal. Just pull the right side case cover of and check it out. It won't affect it running.

 

i push the kickstart down and sometimes the crank turns and sometimes it doesn't????

 

Probably the spring inside is ****ed up. On my KX250 I had the same thing happen. I pulled it apart and a clip had let go. I put it back and it works great now. I think you may have to split the cases on the 80 to get to it though. I would concentrate on getting it running first then mess with little ****. Do a compression test, look at the piston for blow by and check the crank bearings. If you end up splitting the cases, replace the crank bearings and seals while you are in there. You'll thank me later. What year is the 80?

 

u need to put a light bore on it and a new piston and rings sounds liek he ran in lean and seized it

 

if i remeber my kx 80's properly its probably the kick start gear itself
those have plastic gears on the kick start a very common problem on them
is shearing teeth off
a new gear and a clutch cover gasket
will remedy that, if its a watercooled model i would suggest the mechanical seal for the waterpump while you got the cover off

 

Sounds like the kickstart is messed up if it is a hit and miss thing when trying to turn the engine over. Remove the flywheel side cover on the engine and turn the engine over by hand. You should be able to feel if everthing feels good or if there is excessive play or excessive resitantce to turning. From my experience with 2 strokes if you plan on keeping it for a while, tear the engine down, (split the cases) replace the crank bearings and seals, replace the lower rod bearing ( made this mistake once), you'll have to have a shop with a press, press the crank apart and install the new bearing and press the crank back together. Mic the cylinder for wear, replace the piston,rings, wrist pin and wristpin bearing. Basically a total rebuild but it will be worth it if the rest of the bike is in good shape. Those little 80's are real screamers. Good luck!!!

 

sounds like you got a hellofa good deal for $20, just take ur time and fix it right, i think it might be the kickstarter too.
B

 

You may have a oversized piston that wont go in the jug, or oversized rings.

 

ya i'm goin to take it to a friend that works at the local dealership and have him split the cases for me the i will see what wrong and sooner or later it will be runnin, i will prolly get rings,piston,bearings,gasket set,clutch, and that will prolly be it, i'm pretty sure its and 86 and it is water cooled, in my opinion i got a really good deal because it is in pretty good shape other than the motor and it came with new answer bars that i could sell for almost the price i paid for it i will post some pics of it tommorrow if Danimal doesn't try to steal any more parts off it!!!!

 

have you tried bumping it?

 

i had a KLX 250 same thing happened had to bump it all the time