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Pits in CR125 head...

IndyMX

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#1
Can anyone tell me what might have caused the pitting in my head, and what effect it might have on performance and what I should do about it?

http://home.quickinet.net/_MG_2075.JPG

I also noticed, while I had the cylinder off today, that it had been ported. And there is a Wisco piston in it.

Is there a good way to tell if it has been over bored?


BTW, I haven't noticed any issues with the way it runs.. Seems like it's running pretty good to me. And quite quick!
 

Chili

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#4
I'd agree with detonation as well for the head. As far as an overbore, measuring the piston would likely be the easiest way.
 
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#7
yes i would use higher octane, and maby some booster. You can use a dremel to grind out the head and aslo a cheap way to portpolish.
 

IndyMX

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#9
76GMC1500 said:
What octane are you running and what spark plug?
Just a guess, but since the pits are only in the head and not in the piston, it's damage that was done before I got the bike. And it seems obvious that it's damage that was done prior to a topend being done.

I'm guessing that it also has nothing to do with detonation, but with part failure.

For what it's worth, I am running 93 octane with a BR8ES plug.
 
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#10
Indy,some joker before you lost a bearing! You could send that head to Eric for race gas and order another new one,But I do not know if you can get a new one by sunday! You could just knock the high stuff off and wash it in warm soapy water. Is the piston flat or domed? I sure hope none of these hacks with dremel tools been at your ports! Need pics STAT!
 

IndyMX

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#11
whenfoxforks-ruled said:
Indy,some joker before you lost a bearing! You could send that head to Eric for race gas and order another new one,But I do not know if you can get a new one by sunday! You could just knock the high stuff off and wash it in warm soapy water. Is the piston flat or domed? I sure hope none of these hacks with dremel tools been at your ports! Need pics STAT!

Yeah, the piston is a Wiseco.. Flat. Already knocked off the high spots. Still runs.

Someone has been at the ports, not sure if it was a hack or not, but as soon as I get done with it at the bud, I'll tear it back down and take some pics of the ports.
 

IndyMX

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#13
whenfoxforks-ruled said:
Was the exhaust port realllll shiny?
Not really... It has been worked on, that's obvious and shiny, yeah.. But not polished.

The transfer ports have also been worked.

As compared to another 2000 CR125 I rode last year, it seems quicker. But who knows..

When I take it back apart, I am gonna measure the piston, see if it's oversized.

After taking a look at it Monday, I have no idea what I have in there now.
 
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#14
The guy i baught my bike of of blew the crank bearing and pitted the head, mine is really bad but she still kicks. Of corse i had to get the cylinder re-sleeved and the crank redone i had some port work done to my cylinder as well. Im not too sure of what they did because i was new at the time to porting but is there a way to match up what my ports look like and what they did to improve what part of the Powerband?