2005 cr 144 top end failure

JA946
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JA946 8/20/2014 9:25am
8/20/2014 9:25am
I have wiseco in my CR250 - and it's worked well.

I had a vertex in my CRF - no lie, that piston was beautiful.
Paw Paw 271
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Paw Paw 271 8/20/2014 10:31am
8/20/2014 10:31am
If you look at the piston photo closely you will see the ring seized to the ring grove in the piston exactly at the exhaust port.

Paw Paw
godog
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godog 8/20/2014 12:53pm
8/20/2014 12:53pm
Just curious about the temp change from the day before and the next morning? if its on the edge in the heat of the day and you loose 20 deg in the morning that can be an issue. Most if not all cr125 motors have issues with pushing the left side crank seal out and up against the stator plate which can cause a very small leak which for most bikes its not a problem unless your jetting is on the edge to begin with. If the cylinder /piston clearance is an issue doesn't the smear go pin to pin on both the front and back? If there was a heat (lack of warm up) issue don't the pistons show signs of a "four point" seizure before they smear all over the place? The reliability of 91 or better pump gas in the US is a real problem. Although there isn't any peppering on the piston crown from deto that may not mean that your exhuast gas temp isn't thru the roof. Just food for thought.
Jakes Dad
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Jakes Dad 8/20/2014 6:25pm
8/20/2014 6:25pm
A tool I've used for many years through drag (bracket) racing, karts and now mx with my kid.
http://www.pilotfriend.com/calcs/calculators/density.htm

Use your phone go to weather.com and plug in what's needed to calculate, you just need to know the elevation of the track you are at, found online also. Once you get a baseline after a few trips to the track you can use it wherever you go.

This and a laser temp checker are good tools to tune by. With proper reading of the plug of course.

Does that bridge have an .002 or better relief cut in it?

The Shop

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JA946
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JA946 8/21/2014 11:04am
8/21/2014 11:04am
Jakes Dad wrote:
A tool I've used for many years through drag (bracket) racing, karts and now mx with my kid. http://www.pilotfriend.com/calcs/calculators/density.htm Use your phone go to weather.com and...
A tool I've used for many years through drag (bracket) racing, karts and now mx with my kid.
http://www.pilotfriend.com/calcs/calculators/density.htm

Use your phone go to weather.com and plug in what's needed to calculate, you just need to know the elevation of the track you are at, found online also. Once you get a baseline after a few trips to the track you can use it wherever you go.

This and a laser temp checker are good tools to tune by. With proper reading of the plug of course.

Does that bridge have an .002 or better relief cut in it?
We didn't even use this website - before the web, my dad would use a calculator and a home made weather station for calculating density altitude. Even cooler, inputing injector size, pump flow, CI of motor along with other variables, his program would tell you which jet to use in the mechanical fuel injection.

Ahh, the 80's live on!
seth505
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seth505 8/21/2014 11:26am
8/21/2014 11:26am
Spinnin t's wrote:
Wossner is forged also. Never used there stuff before. A forged piston if set up tight needs more "break in" time than 45 min. Reason I...
Wossner is forged also. Never used there stuff before. A forged piston if set up tight needs more "break in" time than 45 min. Reason I said something about the morning practice is I assume it was a race day. Usually morning practice is deep and wet. If it gaulded in 4 courners it just didn't have enough clearance. I really think the jetting was fine. Plus what paw paw said.
seth505 wrote:
You could cold seize a forged piston but you are saying you need to break it in over 45min?
Spinnin t's wrote:
My first rule is if you have to break it in it was sh*t to begin with. But on a side note if you use a...
My first rule is if you have to break it in it was sh*t to begin with. But on a side note if you use a forged piston mainly in a 2t and have the clearances set to the tight side of the book.. It needs a tank of fuel at least. It just has to do with the rate they expand. Now I've seen pistons stick on the exhaust bridge. Unless I didn't see it right that's not what happened. Either it just stuck due not not enough clearance,dirt,or bad piston or bad cylinder plating. Either way Eric should get you back on track. The only forged 2t piston I will use is a Athena. They have other material in the piston that helps control expansion. The stock top end lasted bc it was stock. The 144 will draw more fuel than the stock cylinder. So jetting should not be it. But could be a piece of a lot of stuff.
I have never heard this about a long break in. I have used forged pistons for a long time now in 125s and 250s and always am sure to warm them up properly before motoing but never a full on 45min+ break in period.
Spinnin t's
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Spinnin t's 8/21/2014 3:05pm
8/21/2014 3:05pm
I have never had a problem either but if it's not set up right it breaks.
team466
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team466 8/21/2014 3:05pm
8/21/2014 3:05pm
I spoke to eric himself on the phone yesterday afternoon. He thinks it is a combination of things. 1 pump gas is very unreliable.2 if we were on the edge with our jetting on saturday afternoon, the temp change, being the seizure happened during morning practice may also be a big factor, the temp was about 15 degrees cooler that morning. I am sending the entire top end back to him and he said he would take care of it for me. He also asked what pipe we run because the sst pipe runs hot on the 144 due to the narrow stinger. we run a full bills pipe and I looked at the pipe compared to stock and it does apear that the stinger is narrower than the stock one.Eric said that I should go up 3 sizes on the main and work my way back if i need to, this made sense when he said it and in hindsight is what I should have done in the first place.I thank all you guys for your input and information, this is what I love about our racing and riding community. I will post the end results when I get the top end back from eric. Thanks again guys.
Camber75
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Camber75 8/21/2014 7:28pm
8/21/2014 7:28pm
Glad to read the customer service is top notch, boxing up a kx 125 top end to send out there for a 144 kit as well!

Pit Row

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