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what happened to my bike?

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I was racing my 03 rm125 today at a harescramble. The conditions were sandy and dusty. I was pretty much pinned everywhere on that wide open track and I was in 2nd, chasing the leader and 1 mile from the finish line my bike took a shit. I replaced the piston 5 hours ago, so i was a little upset. It's not your usual blown top end where there is no compression. I thought maybe it was siezed but its not locked up either. the kicker goes down and it actually has more compression than when i started the race. Do you guys have any ideas? Bottom end maybe?

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Getting fuel? Getting spark? Did it make any noises or just die? Hard to tell...

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Getting fuel? Getting spark? Did it make any noises or just die? Hard to tell...

it was good on fuel because i had just pitted and there's no way i fouled a plug because i just riding it way to hard. and it kind of whined and bogged before dieing.

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If you have compression I'd say the top & bottom end are OK. Check for spark and fuel.

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Just like trueweb said, start with the basics check for spark make sure your getting fuel. When my bike died the powervalve came apart but thats not common on newer 125s (different type of PV assemble).

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It's busted, pull the jug off and inspect the damage. the skirt of the piston is probably broken off and now it is rubbing against the crank.

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It's busted, pull the jug off and inspect the damage. the skirt of the piston is probably broken off and now it is rubbing against the crank.

would i need a new crank?

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Just like trueweb said, start with the basics check for spark make sure your getting fuel. When my bike died the powervalve came apart but thats not common on newer 125s (different type of PV assemble).

when that happened what did the damage cost because i believe the clip that holds that rod in the pv was already broken

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would i need a new crank?

Maybe, maybe not. you should get it rebuilt though so they can rebalance it and it is cheap insurance against bottom end failure. If what I said is your problem.

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In my case the PV slid into the cylinder and was then whached by the piston. I was lucky because the jug didn't get damaged. I ended up replacing the PV and top end.

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