PLEASE HELP CORROSION ON HEAD WORRIED !!

[Alcorn859]

[EmpireofDerp]

Looks like carbon build up, not corrosion. Ooh sorry, on my phone, yeah that thing is all ate up. Never seen that before.

 

 

[Alcorn859]

Ignore the gouges in the piston that was done after the corrosion of the head was found 

[Treesmacker]

That looks like detonation.

I bought a YZ125 that looked like that, the kid I bought it from was running a SST pipe on pump gas.

Eric Gorr said the result was from detonation, He turned it into a 144 for me.

Edited May 31, 2017 by Treesmacker

[Alcorn859]

I'm talking about the jug and head corrosion the marks in the piston are from me stabbing it when I found the corrosion 

[FORMA MOTO]

That is not corrosion, it is detonation damage.

http://www.contactmagazine.com/Issue54/EngineBasics.html

[Alcorn859]

So what did I do wrong ? And how do I fix this ? 

[Treesmacker]

10 minutes ago, Alcorn859 said:

So what did I do wrong ? And how do I fix this ? 

Retard timing or use Race Gas.

[Alcorn859]

C12 race fuel was used no ethanol pump gas at all 

[Alcorn859]

How do I get this fixed ? I was installing new piston when I discovered this... and decided to jam a flat blade screw driver in the piston when I saw it haha 

Edited May 31, 2017 by Alcorn859

[Nevada Al]

timing or jetting/ fuel delivery would be my guess too..  Is the head machined?

[Alcorn859]

Head is cut ! And I only took this motor apart for inspection and found this corrosion I was using pure race gas. 

[Alcorn859]

Yes head is machined

[markmc2]

30 minutes ago, Alcorn859 said:

Yes head is machined

is it a yz250? you previously had it machined for specific application (mx, offroad, gas type)? what is your timing set at?

[Home Skillet]

Too high compression will cause detonation.

[ossagp]

18 hours ago, Alcorn859 said:

So what did I do wrong ? And how do I fix this ? 

For grins,  lift up the orings and take a pick and show them please.  what is your history with this engine?   Did you put the last piston in it?

[Smoking 2's]

Unless your pro mx check is at risk, clean it and ride on!

[Alcorn859]

What size piston should I use on a brand new cylinder ?