Two-Stroke Dirt Bike Issue

[Rossim22]

Yesterday while my little brother was riding his RM80, it bogged down and stalled. He tried starting it again there, but had no luck so he pushed it home. After many unsuccessful tries starting it in the garage, I tried a couple times. I leaned the bike over, emptying the fuel lines and flooded engine, then tried again.

The first two kicks almost started it and on the third, the kick start didnt budge. It moves down about an inch then comes to a stop, no matter if I put all my weight on it. I don't think it's possible that the piston is seized since I just put in a fresh top end a couple weeks ago, and because the kick start went up and down fine when it was flooded, then stopped out of nowhere.

So I have yet to pull the head and see if the piston moves up and down by itself, but does anyone have any other ideas? I'm going to take off the cover as well, to see if the kick start is jammed somehow... but does anyone have any experience with this?

[Rossim22]

Took off the head and the piston is seized at the bottom of the combustion chamber. :confused

[Rossim22]

Well since I'm on a roll with responses I'll update the situation...

The piston's skirt is completely shattered. The metal inside the crank case is what caused the kick start to jam. So my new question is... what next? How do I get a piston out of an engine with a crank that is jammed with metal flakes the size of my thumb nail?

http://i34.photobucket.com/albums/d120/rossim22/piston2.jpg
http://i34.photobucket.com/albums/d120/rossim22/piston.jpg

[Jeffie ON JUICE]

bore it out make it a 90cc

[BlackMagicGTO]

take it to someone and let them fix it

[Rossim22]

bore it out make it a 90cc

Lol woooooo bring on the power. It does not need to be bored because, as of right now, the cylinder wall looks good. But I cannot take out the old piston because the crank is partially turned over and because theres metal inside I cannot turn it over. Is splitting the case my only option?

[Rossim22]

take it to someone and let them fix it

I took it to someone for the top end to be replaced... now my piston is inside my crank case....

[95w_bTEG]

yup, split them.

[Rossim22]

yup, split them.

Sweeeeet... any tips for a first-timer?

[Anthony]

if the piston looks like that i really doubt the cylinder walls are fine just saying

[e36rcr]

if the piston looks like that i really doubt the cylinder walls are fine just saying

lol agree..

try a magnet?? I duno if that shit is magnetic. and for future reference, when a 2-stroke dies on you like that PLEASE don't try to kick start it... best thing to do is check the head... you can ONLY do more damage by doing so. it doesnt matter when you replaced the top end its a 2 stroke lol

[Rossim22]

lol agree..

try a magnet?? I duno if that shit is magnetic. and for future reference, when a 2-stroke dies on you like that PLEASE don't try to kick start it... best thing to do is check the head... you can ONLY do more damage by doing so. it doesnt matter when you replaced the top end its a 2 stroke lol

Youre telling me that if a dirt bike I'm riding bogs down on me, I should not kick start it? It's kinda hard to tell when youre in the middle of a field if anything went wrong internally lol. I'll check out the cylinder wall and see if thats destroyed.

[Rossim22]

if the piston looks like that i really doubt the cylinder walls are fine just saying

lol agree..


http://i34.photobucket.com/albums/d120/rossim22/cylinder.jpg

[+Juan]

Id still get it re-honed to be on the safe side. you know how picky 2-strokes can be.

[Rossim22]

Id still get it re-honed to be on the safe side. you know how picky 2-strokes can be.

Lol, i'll worry about the re-honing after I get the chunks of metal out of the crank case. To do this... do I just jump oil through the top under the piston and let it drain out?

[OkiNutsEP3]

You just rebuilt the top end right? Did you do it, or somebody else? Was the ring, at the index mark in the piston? Was the arrow, or dot on the piston towards the exhaust side of the engine?
You can remove your piston ya know. Get a 90 degree pick, or a small (freebee) flat screwdriver, and work you way around the circlip, and it will come out. once out, slide your piston pin out.

[Rossim22]

You just rebuilt the top end right? Did you do it, or somebody else? Was the ring, at the index mark in the piston? Was the arrow, or dot on the piston towards the exhaust side of the engine?
You can remove your piston ya know. Get a 90 degree pick, or a small (freebee) flat screwdriver, and work you way around the circlip, and it will come out. once out, slide your piston pin out.

I did not rebuild the top end, a friend did who has done it many times before. This bike is my little brother's, so it was my mom's idea to have him do it since I never have. He said it was the piston, but I looked up the specs on the piston I bought and the piston that was in there before the top end, and they're identical.

I'll work on removing the piston from the crank right now. I am buying a 1993 rm80 lower end off someone from ebay. It's the full engine, clutch, stator, crank, clutch... everything minus the cylinder and piston. So I am going to just swap them out, that way I do not have to split the crankcase myself.

[OkiNutsEP3]

You do know this is what I do for a living right??

[Rossim22]

You do know this is what I do for a living right??

I did not know... I wasn't disagreeing with you on anything if that's what you're inferring... ? I'm going to try to take out the piston tomorrow morning when I have a little more light to work with.

[Anthony]

just have him do it for you ross,thats what he does and i believe what he was getting at

[OkiNutsEP3]

I wasn't being negative, but I possibly could help you.

[Rossim22]

I wasn't being negative, but I possibly could help you.

Oh ok, well I'm no longer going to buy the extra low end because I asked "Are there any known issues with the lower end?" and the guy went off on me because how is he supposed to know if everything works if it's been sitting in his shop for three years... so I took that as a sign that its probably toast.

Now it looks like I will be removing the engine and splitting the crankcase to try to remove the metal thats keeping the kick start from moving at all.

[Rossim22]

With the head off and the piston exposed, still installed in the lower end, should there be any sideways play? The connecting rod moves side to side very little... maybe this caused the piston to shake itself to pieces?

[OkiNutsEP3]

Side to side is ok. Up and down is no good.