2005 cr 144 top end failure

team466
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8/18/2014 9:35pm Edited Date/Time 8/21/2014 7:28pm
I just had eric gorr do a 144 conversion on my sons 2005 cr 125. I sent them the entire top end when i shipped it, piston ring and last used plug included. They told me the jetting looked pretty good, although i may want to go one size up on the main, I asked for more mid to top.I went up one size on the main as suggested during the install. We rode a practice day on saturday to make sure things were good. plug one was taken out after a 15 minute ride. The color look good so I put in a new plug and he rode 2 more 15 minute sessions. He said the bike felt real strong and was not pinging. Changed the air filter and put it up for the night. During morning practice the top seized. Plug 2 is the plug taken out after the seizure, all white on the insulator and no color. A friend had a 125 cylinder and top end so we installed it using the modified head. Son rode 4 motos on that set up. Plug 3 was taken out after those 4 motos, some color but not as much as I would have thought, I did not change the jetting. Any ideas about what may have caused this failure?











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JA946
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8/18/2014 11:55pm
Lean jetting. Just because you don't hear it ping, doesn't mean there isn't preignition happening. Looks like it got pretty hot, and pics of the underside of the piston?

What fuel, oil and ratio?
Paw Paw 271
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8/19/2014 3:12am
I don't see lubrication holes for the exhaust port bridge in the piston. That can cause quick failure of the piston.

Paw Paw
Spinnin t's
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8/19/2014 7:12am
Well if that's a wiseco piston and the bike had 45 minutes on it b4 morning practice. That don't help matters any. Usually morning practice is deep so that will put a load on the bike. , crapy wiseco needed more run it time, or it just got hot.
seth505
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8/19/2014 7:23am
Well if that's a wiseco piston and the bike had 45 minutes on it b4 morning practice. That don't help matters any. Usually morning practice is...
Well if that's a wiseco piston and the bike had 45 minutes on it b4 morning practice. That don't help matters any. Usually morning practice is deep so that will put a load on the bike. , crapy wiseco needed more run it time, or it just got hot.
???

The Shop

team466
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8/19/2014 7:38am
It's a wosner piston that Eric has made for them
Spinnin t's
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8/19/2014 9:26am
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.
Team Ideal
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8/19/2014 9:32am
What pipe are you using? The 144 doesn't like the FMF SST, did that exact same to ours exceptwe were on Yamaha's. Ours was fine with the Fatty though.
team466
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8/19/2014 10:33am
Spin, it was morning practice race day. How much break in time should be allowed for a forged piston.
Ctb, I will check that link , used same fuel, no loss of coolant, I thought it odd too that 2 nd cylinder ran ok .
We run a full bills pipe and silencer , Eric said there should be no problem with it. Thanks for the replies guys , keep the info coming, my kid was ripping on it when it was going, need to get it figured out.
JA946
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8/19/2014 10:48am
team466 wrote:
Spin, it was morning practice race day. How much break in time should be allowed for a forged piston. Ctb, I will check that link...
Spin, it was morning practice race day. How much break in time should be allowed for a forged piston.
Ctb, I will check that link , used same fuel, no loss of coolant, I thought it odd too that 2 nd cylinder ran ok .
We run a full bills pipe and silencer , Eric said there should be no problem with it. Thanks for the replies guys , keep the info coming, my kid was ripping on it when it was going, need to get it figured out.
Pics of the underside of the piston, please.

Also, Why aren't the exhaust bridge holes drilled?
Paw Paw 271
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8/19/2014 11:02am
Again....If you don 't put the lube holes in the piston so that the exhaust bridge can be lubricated you will continue to have piston failure no matter how much break in time you give it.

Paw Paw
seth505
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8/19/2014 11:05am
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.
You could cold seize a forged piston but you are saying you need to break it in over 45min?
Team Ideal
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8/19/2014 11:26am
Forgot to mention I agree with Paw and JA. I'm thinking there are a few pistols you have to drill your own holes. Still shouldn't be that much dif in plug colors between the three though
team466
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8/19/2014 12:55pm






third photo is of failure/exhaust side. there are two oil holes drilled near the top of piston.
team466
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8/19/2014 1:02pm
I just dont get the difference in the the plug colors and the inconsistent burn pattern on the top of the piston. The rest of the piston skirt also looks fine, no scratches or galling, its just on that exhaust side. i a, thankfull for all the input guys.
JA946
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8/19/2014 2:00pm Edited Date/Time 8/19/2014 2:02pm
See post below.
JA946
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8/19/2014 2:01pm
team466 wrote:
I just dont get the difference in the the plug colors and the inconsistent burn pattern on the top of the piston. The rest of the...
I just dont get the difference in the the plug colors and the inconsistent burn pattern on the top of the piston. The rest of the piston skirt also looks fine, no scratches or galling, its just on that exhaust side. i a, thankfull for all the input guys.
What fuel and oil? What ratio?
team466
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8/19/2014 3:02pm
93 octane fresh, honda hp2 oil, mixed at 32:1
Matt Fisher
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8/19/2014 3:48pm
Wasn't running lean or overheating based on the underside of the piston.

It's rare, but maybe the coating is flaking off the cylinder. That, or it ingested some dirt. The slightly shiny color of the piston makes me think the coating is coming off, but usually it's nowhere near that much grinding on the piston.

The streaks on the cylinder- are they carved into the wall of the cylinder, or are they bits of aluminum deposits on the cylinder wall? Take a SOS pad and see if the streaks can be scoured off. If they can, I'd lean toward it being a dirt problem.

The cylinder coating is amazingly tough. Several years ago we were at Pismo dunes, with my son on a paddle tire equipped RM65. He would leave it in third gear, wfo, for minutes at a time. At some point the water pump seal failed and he ended up running it sans coolant. It seized going up a big dune, tight as a drum. Got it home and pounded the piston out, used muriatic acid and an sos pad to clean the cylinder up. No damage to the cylinder, even the crosshatching was still good! Bike ran like a top for 2 more years with just normal piston changes.
Jakes Dad
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8/19/2014 6:11pm
Weird looking piston wash from the transfers, it is lean but very unbalanced flow. No sign of a tight (proper squish). No cooling ring affect around the perimeter results in heat build up until failure.

Check reeds (weird flow from somewhere) and most definitely check squish.
JA946
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8/19/2014 7:43pm
team466 wrote:
93 octane fresh, honda hp2 oil, mixed at 32:1
Ahhh pump gas, I'm going to blame that inconsistency with on the edge jetting, and you lunched your top end. What fuel is the squish set for? Gorr motors notoriously require AT LEAST 50/50 pump with C12.

How well sealed is your air box?
Mickolobe7
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8/19/2014 8:27pm
Again....If you don 't put the lube holes in the piston so that the exhaust bridge can be lubricated you will continue to have piston failure...
Again....If you don 't put the lube holes in the piston so that the exhaust bridge can be lubricated you will continue to have piston failure no matter how much break in time you give it.

Paw Paw
Sorry not trying to jack you Thread. Just have a quick question.

Pawpaw would you drill holes in the piston for a pw50 rebuild? If so wear would you drill them for the pw? Thanks
bd
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8/19/2014 11:36pm
Race Engine = Race Gas

Jakes Dad
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8/20/2014 3:52am
Again....If you don 't put the lube holes in the piston so that the exhaust bridge can be lubricated you will continue to have piston failure...
Again....If you don 't put the lube holes in the piston so that the exhaust bridge can be lubricated you will continue to have piston failure no matter how much break in time you give it.

Paw Paw
Mickolobe7 wrote:
Sorry not trying to jack you Thread. Just have a quick question. Pawpaw would you drill holes in the piston for a pw50 rebuild? If so...
Sorry not trying to jack you Thread. Just have a quick question.

Pawpaw would you drill holes in the piston for a pw50 rebuild? If so wear would you drill them for the pw? Thanks
The narrow strip of metal that divides the exhaust port is called the bridge. Being that it is so narrow it heats up and expands starting the seizure. By drilling holes in your piston directly across from the bridge will allow the residual 2 stroke oil in the crankcase to be drawn up and through these holes and coating the bridge cooling it down. Millenium and other companies cut a relief of .002 or more to compensate for the expansion of the bridge.

One of the reason's I like the Suzuki 125 it has a triple ex port and no bridge. As far as a PW I don't think they have a bridge in the port. The bridge keeps the piston rings from bulging out too far and then hanging on the edge of the port.
YZ125H1
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8/20/2014 5:05am
team466 wrote:
93 octane fresh, honda hp2 oil, mixed at 32:1
JA946 wrote:
Ahhh pump gas, I'm going to blame that inconsistency with on the edge jetting, and you lunched your top end. What fuel is the squish set...
Ahhh pump gas, I'm going to blame that inconsistency with on the edge jetting, and you lunched your top end. What fuel is the squish set for? Gorr motors notoriously require AT LEAST 50/50 pump with C12.

How well sealed is your air box?
I'm thinking the jetting was right on the edge also.
motofab36
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8/20/2014 5:13am
What did Mr Gorr say?
MX Dad #27
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8/20/2014 8:03am
bd wrote:
Race Engine = Race Gas

BINGO! Eric did our '06 CR 144 we were told to run ONLY RACE FUEL.
He had Wiseco making his pistons then (for the people making negative comments about Wiseco pistons we ran their 101.5's and their 144's with NO PROBLEMS EVER).
Spinnin t's
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8/20/2014 8:07am
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?
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.
Jakes Dad
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8/20/2014 8:25am
Nothing wrong with Wiseco's or most any brand "as long as you take the time to measure the bore and measure the piston". Then have a good squish to prevent detno and all should be good with proper tuning.
Spinnin t's
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8/20/2014 8:37am
Wiseco is fine for the guy that works on his own stuff. But when you use 50 a year and 10 are shit... Well you go to a more reliable brand. I will say the best piston I have ever used was a wiseco. But after getting the right guy drunk after a national and it being a prototype team only product I'll never get another one of those again. It was a 450 piston anyway. 4t stuff seems to be fine. You must have never took one of there cranks out of the box and put it straight on a truing jig? It will vibrate your hands off the bars if installed. lolSorry off topic...

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