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Author Topic: Blew it up!  (Read 5481 times)

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Offline ACMX

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Blew it up!
« on: April 15, 2012, 11:13:56 PM »
Photos and video of it siezing at the bottom...

~10 hours on this rebuild and she seized. Small water leak. It overheated. Suspect it was one of the the o-ring head gaskets. I could just rebuild it but I suspect I may need a new cylinder. Or just need it re-sleeved?
I checked the crank... It has no up/down play.

What do you guys recommend?
If I get a new cylinder, should I get OEM ($335) And if I take this option would I need new cyl. head too? or an Athena big bore (entire kit ~ $700)..?
Or just resleeve it?

As for the piston I have 3 options... Wiseco, Pro-X, or OEM (I get discount on Wiseco and Pro-X)

Bike is a 2003

Skip to close to the end of the video...




« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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'Forgive me lord for I have sinned. I hit a fourth gear jump in fifth gear pinned'

The Sweet Sound of a Yz125 Two Stroke
http://www.youtube.com/watch?v=TSO3Po7uvJo

'If it takes more than two strokes, then you're just playing with

Offline xandyx

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Blew it up!
« Reply #1 on: April 16, 2012, 12:42:14 AM »
shit man! i'm sorry for you :-X

if you need a new barrel, i'd go for the athena, a few more quid, but it will feel like a new bike.

get a wiseco piston and drill 2 small holes on it to help lubricate the cylinder a bit better!

« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline ford832

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Blew it up!
« Reply #2 on: April 16, 2012, 12:50:36 AM »
I'd go for a wiseco and a 139 kit. 8)
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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Blew it up!
« Reply #3 on: April 16, 2012, 02:00:15 AM »
Unless your head is warped, just get the cylinder re plated, or worse case, re sleeved. I had the same thing happen to my 250. The choice in piston is up to you, but if you get discount on wiseco, save some cash. If I could recommend a re-platter, I would suggest millennium technologies. They did great on my cylinder, and even bead blasted it.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline xandyx

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Blew it up!
« Reply #4 on: April 16, 2012, 03:40:14 AM »
it seems that the bike was bogging in the last minute of the video before it staled. is it my impression, or were you feeling it loosing power?!
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline factoryX

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Blew it up!
« Reply #5 on: April 16, 2012, 04:47:38 AM »
Could have been trying to hydro lock ha.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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I ride an 03 yz250, wait 04, wait 05, what ever, they're all the same #$@% YOU!

Offline ACMX

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Blew it up!
« Reply #6 on: April 16, 2012, 06:55:49 AM »
Quote from: xandyx on April 16, 2012, 10:40:14 AM
it seems that the bike was bogging in the last minute of the video before it staled. is it my impression, or were you feeling it loosing power?!
It had lost a TON of power on that last lap. Zero compression.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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'Forgive me lord for I have sinned. I hit a fourth gear jump in fifth gear pinned'

The Sweet Sound of a Yz125 Two Stroke
http://www.youtube.com/watch?v=TSO3Po7uvJo

'If it takes more than two strokes, then you're just playing with

Offline 2T Institute

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Blew it up!
« Reply #7 on: April 16, 2012, 08:16:40 AM »
I would have had a new piston or untrapped the ring , sanded the piston down, hit the cylinder with acid and been racing it again in an hour or so after that.
I don't know why you kept wringing it's neck when there was clearly something wrong.
Your piston looks a bit lean which is why I would say it's over heated. A good pic of the piston will tell.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline SachsGS

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Blew it up!
« Reply #8 on: April 17, 2012, 12:00:07 AM »
I'd check the head and cylinder for "flatness"The head looks like it is lifting off the cylinder in the exhaust port area.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline ACMX

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Blew it up!
« Reply #9 on: April 17, 2012, 08:55:25 AM »
Quote from: 2T Institute on April 16, 2012, 03:16:40 PM
I would have had a new piston or untrapped the ring , sanded the piston down, hit the cylinder with acid and been racing it again in an hour or so after that.
I don't know why you kept wringing it's neck when there was clearly something wrong.
Your piston looks a bit lean which is why I would say it's over heated. A good pic of the piston will tell.
When the top end is going out in this fashion, if you don't keep rpm up it dies out. I was trying to find a safe place to exit the track as soon as I realized something was wrong. I didn't want to get stuck in the middle of the track with bike going all around me.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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'Forgive me lord for I have sinned. I hit a fourth gear jump in fifth gear pinned'

The Sweet Sound of a Yz125 Two Stroke
http://www.youtube.com/watch?v=TSO3Po7uvJo

'If it takes more than two strokes, then you're just playing with

Offline 2T Institute

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Blew it up!
« Reply #10 on: April 17, 2012, 09:50:06 AM »
Ring traps at about 7.50min in the video and at 8.50 you pull of the track. There was more than ample opportunity to pull safely off the track. As I said if you would have stopped the bike pushed it back to the pits and untrapped the ring sanded the piston you would have been out for the next race. The pick up on the cylinder is from running hard with a partialy trapped ring.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline scotty dog

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Blew it up!
« Reply #11 on: April 17, 2012, 12:07:31 PM »
Love the vid, your railin, you would haul on a 250 ;)
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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F**K THE WHALES......................SAVE THE 2 STROKE!!!!

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Offline juliend

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Blew it up!
« Reply #12 on: April 17, 2012, 11:11:39 PM »
You should be able to re-plate and install new piston and rings for around $300. No sleeves!
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline Super Trucker

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Blew it up!
« Reply #13 on: April 18, 2012, 05:45:52 AM »
It sucks that your bike locked up,sorry it happened to ya. I got lucky a couple times, when I pulled the choke to prevent a lock up. Other times when I locked it up, I just kick the cylinder loose, hone it, and slap it together. If the rub marks are not deep, I would just hone it.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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Blew it up!
« Reply #14 on: April 18, 2012, 05:48:13 AM »
Quote
I would just hone it.
I don't think you can hone it. Aren't the yz125's nikasil platted?
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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