2 stroke help

dak
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dak
Edited Date/Time 1/27/2012 4:53pm
I ride a 2004 cr125 and i lost compresion riding one day. I relized it was my top end and that mabie i broke a ring or somthing. I took off the cylinder head and the combustion chamber and piston was dented and chewed like someone started beating it with a screwdriver or somthing. so i think mabie the piston ring broke and got inbetween the cylinder head and the piston and caused havoc. Do you guys think this is right or a tottaly different problem? (im asking beacuse this is my first two stroke and the first time ever doing a top end replacment) thanks
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motogeezer
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motogeezer 7/20/2011 12:14pm
7/20/2011 12:14pm
Sounds about right, but you didn't mention the condition of the ring.

You must have seen it if you took off your top end.

If that's what happened, there are most likely some pieces in your crank case too.

Sorry for your loss.
dak
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dak 7/20/2011 1:13pm
7/20/2011 1:13pm
yeah i havnt taken the piston out yet i only removed the cylinder head. thanks for the help
motogeezer
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motogeezer 7/20/2011 2:19pm
7/20/2011 2:19pm Edited Date/Time 7/20/2011 2:21pm
Oh.

Your post said you took off the head and combustion chamber...

I thought you were talking about the cylinder.

Get to it!!
RMiller227
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RMiller227 7/21/2011 9:24am
7/21/2011 9:24am
i actually had a similar problem with my yz250. thoroughly inspect the cylinder for any scaring or knicks. you may need to replate it if there are any defects. also, you may want to flush out your bottom end to make sure the missing piece of the ring didn't drop in. as far as the cylinder head goes, i was told that mine would be able to be smoothed out at a machine shop, or just pay $130 for a new one.

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dak
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dak 7/21/2011 10:16am
7/21/2011 10:16am
RMiller227 wrote:
i actually had a similar problem with my yz250. thoroughly inspect the cylinder for any scaring or knicks. you may need to replate it if there...
i actually had a similar problem with my yz250. thoroughly inspect the cylinder for any scaring or knicks. you may need to replate it if there are any defects. also, you may want to flush out your bottom end to make sure the missing piece of the ring didn't drop in. as far as the cylinder head goes, i was told that mine would be able to be smoothed out at a machine shop, or just pay $130 for a new one.
Yeah i can get a new one online for $60
dak
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dak 7/21/2011 10:19am
7/21/2011 10:19am
motogeezer wrote:
Oh.

Your post said you took off the head and combustion chamber...

I thought you were talking about the cylinder.

Get to it!!
I ment the combustion area on the bottom of the cylinder head. the sides of the cylinder are smooth the only thing thats messed up is the top of the piston and the bottom of the cylinder head
Kryan5
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Kryan5 7/21/2011 10:31am
7/21/2011 10:31am
RMiller227 wrote:
i actually had a similar problem with my yz250. thoroughly inspect the cylinder for any scaring or knicks. you may need to replate it if there...
i actually had a similar problem with my yz250. thoroughly inspect the cylinder for any scaring or knicks. you may need to replate it if there are any defects. also, you may want to flush out your bottom end to make sure the missing piece of the ring didn't drop in. as far as the cylinder head goes, i was told that mine would be able to be smoothed out at a machine shop, or just pay $130 for a new one.
STFU noob! haha
motogeezer
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motogeezer 7/21/2011 10:43am
7/21/2011 10:43am
It seems to me that a broken ring pretty much guarantees cylinder damage.

Did you check to see if maybe an electrode broke off your spark plug?

That wouldn't cause a loss of compression unless the center electrode broke loose from the insulator, but it's something to look at.
RMiller227
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RMiller227 7/21/2011 10:46am
7/21/2011 10:46am
RMiller227 wrote:
i actually had a similar problem with my yz250. thoroughly inspect the cylinder for any scaring or knicks. you may need to replate it if there...
i actually had a similar problem with my yz250. thoroughly inspect the cylinder for any scaring or knicks. you may need to replate it if there are any defects. also, you may want to flush out your bottom end to make sure the missing piece of the ring didn't drop in. as far as the cylinder head goes, i was told that mine would be able to be smoothed out at a machine shop, or just pay $130 for a new one.
Kryan5 wrote:
STFU noob! haha
Sir, there is no need for your immature comments on this post. The individual was simply asking for any feedback regarding his situation. While you are on here looking for topics to comment on, i am out putting in the laps at my local track to show you around on race day.
Kryan5
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Kryan5 7/21/2011 11:02am
7/21/2011 11:02am
Judging from last weekends results you need more practice than i do! haha. Ok i'm done thread jacking! Also, Dak if it was your ring you may not find pieces because they can get smashed up into small pieces and get blown out you exhaust. Also a ring does not always mean cylinder damage, but it can. The rings are made from a softer material than the nikasil cylinder wall. Sometimes you get away unscathed. I'd just replace the top end and see what happens. I scared wall will just wear your rings faster so its not like your going to do more damage. I would also replace the spark plug, put in new top end gaskets, and just take a dynafile or angle grinder with a low grit disk and smooth out the cylinder head. Good luck!
dak
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dak 7/22/2011 10:14am
7/22/2011 10:14am
Kryan5 wrote:
Judging from last weekends results you need more practice than i do! haha. Ok i'm done thread jacking! Also, Dak if it was your ring you...
Judging from last weekends results you need more practice than i do! haha. Ok i'm done thread jacking! Also, Dak if it was your ring you may not find pieces because they can get smashed up into small pieces and get blown out you exhaust. Also a ring does not always mean cylinder damage, but it can. The rings are made from a softer material than the nikasil cylinder wall. Sometimes you get away unscathed. I'd just replace the top end and see what happens. I scared wall will just wear your rings faster so its not like your going to do more damage. I would also replace the spark plug, put in new top end gaskets, and just take a dynafile or angle grinder with a low grit disk and smooth out the cylinder head. Good luck!
ok thanks
dak
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dak 7/22/2011 12:37pm
7/22/2011 12:37pm
ok i got the cylinder off and i only had a chance to look at the piston real quick beacuse rain was coming into my garage and the ring was still there so ill take the piston off when it stops raining and i can open the garage door so i have better light.
motogeezer
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motogeezer 7/22/2011 2:07pm
7/22/2011 2:07pm
Post some pics.

And don't forget to check the electrodes on the plug.
Clint.b2t
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Clint.b2t 7/28/2011 2:29pm
7/28/2011 2:29pm Edited Date/Time 7/28/2011 2:31pm
Does it look like termites ate it? thats called detonation .. i had a 02 rm125 with it edge of cylinder at head , but thats all I know

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