Stop Right there! I gotta know right now...

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5/10/2018 6:33 PM
Edited Date/Time: 5/10/2018 6:34 PM

Before we go any further...

Do you love me?
Will you love me forever?
Do you need me?
Will you never leave me?

OK, enough of the Meatloaf lyrics... This is serious detonation shit caught in the proverbial "Nick of Time"... Vertex cast "B" piston.

04' CR125 ran on 93 E10 pump gas, 32:1 Pro Honda HP2, roughly 5 hours on his top end rebuild with some brisk throttle often... OEM cylinder/head gaskets, but cylinder/head nuts torqued to what we estimate to 26/28 ft/lbs by his minor miscalculation over the OEM 20 ft/lb specs using Motion Pro nut tool. Enough to fuck with the compression!

Get a damned borescope and run good fuel, folks!

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5/10/2018 6:42 PM

SO apart she comes next weekend, done correctly. He also stored the bike with 5-6 month old fuel in the tank and ran it... "Sounds kinda funny". Duh.

Here is what you can see for $25 or so with only pulling the plug:

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That is a toothpick end in the bottom of a beer can...

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5/10/2018 7:02 PM

"Sticker Mechanics need not apply"...

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5/10/2018 7:08 PM

im no master mechanic but i dont see any detonation.

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5/10/2018 7:19 PM
Edited Date/Time: 5/11/2018 2:53 AM

oldandslow1 wrote:

im no master mechanic but i dont see any detonation.

None in the beer can, LOL! I keep my brews cold.

Much erosion at lower center/left of first pic. Note the milling grooves towards the edge are gone compared to the dome, which has taken a minor hit and the pitting all around the lower part of the photo, especially the semi-circular damaged area...

This is how it starts, but ends poorly once the erosion corrupts the lands, ring sticks via land damage and eventually the bitch "gives up the ghost" and eats up the works.

Edit: I am taking a vacation from this place, got too much other work to do. Thank you for reminding me! Over and out.


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5/10/2018 7:33 PM

oldandslow1 wrote:

im no master mechanic but i dont see any detonation.

X2

Paw Paw

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5/10/2018 7:51 PM
Edited Date/Time: 5/11/2018 3:15 AM

oldandslow1 wrote:

im no master mechanic but i dont see any detonation.

Paw Paw 271 wrote:

X2

Paw Paw

OK, I'll give it one last go, Paw Paw. Your opinion is welcomed. What then is going on here causing the erosion? Water absorbed into the fuel? Timing? Lean?

Spark plug is correct type. Bike sounded/ran fine last year when I heard it. It is well beyond what I normally see in my engines after 15+ hours... He said more like 3 on this unit, not 5.

I'll pull his TE for a closer look and dig up some used piston units from my 05'-07' units for comparison hopefully this weekend.

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5/11/2018 6:40 AM

Do you have a link to the bore scope you used? I'd like to pick one up. Thanks in advance!

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5/11/2018 9:06 AM

The difference between 20 to 26/28 ft/lb torque on the head nuts will not affect the compression one bit.

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Powerband in every gear !

5/11/2018 4:03 PM

You lost me at E10

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RTFM & AYFV

5/11/2018 4:50 PM

This is what happens when you put 28 foot pounds of torque on a Honda head, guess what he got some water in the cylinder.

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5/11/2018 11:18 PM

Hmmmm, that one stud sticking up higher than the others...^^^. right at the spot where the head gasket is leaking. Makes me think the stud was not fully seated in the cylinder and the shoulder part of it was sticking up not allowing the head to seat totally against the top of the cylinder. Also, on that generation CR250, it is important to check flatness of the head and the top of the cylinder as they are frequently off and result in leaks like this.

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Powerband in every gear !

5/12/2018 5:45 AM

FGR01 wrote:

Hmmmm, that one stud sticking up higher than the others...^^^. right at the spot where the head gasket is leaking. Makes me ...more

Lo,l he pulled more than one out of cylinder that's just the one you can see. That was a newly plated cylinder, this is one of the pictures he sent to the company and they still warranty it for him, even though it was obviously his fault the cylinder got ruined.

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5/12/2018 8:35 PM

DynoDan22 wrote:

Do you have a link to the bore scope you used? I'd like to pick one up. Thanks in advance!

Here ya go, DynoDan22:

https://www.amazon.com/Depstech-Semi-rigid-Inspection-Megapixels-Waterproof/dp/B06WRNGYXY/ref=zg_bs_401578011_1/131-8967499-3544414?_encoding=UTF8&psc=1&refRID=E451GPZEB2KBFK4VCG5V

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5/12/2018 8:46 PM
Edited Date/Time: 5/12/2018 8:59 PM

RCF...

Ya know, that is a plausible explanation concerning the coolant, as it has a distinct "flow" pattern like coolant migrating across the piston top. He freakin' REUSED the base and head gaskets as well. Jesus, like reusing a condom. It is unfortunate but amusing to corner an offender and painfully extract the details.

Word to the wise: Be totally honest to those willing to help you. Saves time, money, and effort for all involved. I've got an 07' CR125 engine to go through, so he can work along side of me and sort this shit out using MY time schedule. He'll be down for a bit.

You always get more "friends" when they need help...wink

EDIT: Thanks, RCF for your insight.

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5/12/2018 9:11 PM
Edited Date/Time: 5/12/2018 11:26 PM

To corroborate RCF's diagnosis, check the flow pattern... The coolant/moisture flow is being pulled across the piston top towards the exhaust port.

It appears a minor leak, but cumulatively could have had dire consequences if not caught. Good fortune and a $25 tool averted disaster.


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5/12/2018 10:53 PM

RCF wrote:

This is what happens when you put 28 foot pounds of torque on a Honda head, guess what he got some water in the cylinder.

Photo

Look at the cylinder stud well stress fractures... Excuse me, "casting marks"... "Nah, she's been like this since I bought her. She's frisky"... Great pic.

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