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Old 01-05-2021, 07:56 PM
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Default Uh Oh...

Need some help... so I opened my zenoah g320rc engine to put a new piston ring, and I decided to clean the carbon off my piston top, so I grabbed some 500 grit sandpaper, soaked it in some 2 stroke oil, put some oil on the top of the piston and decided to go at it, after that I noticed this...
I hope itís alright.



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Old 01-06-2021, 11:39 AM
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Old 01-06-2021, 11:58 AM
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Originally Posted by the rc guy View Post
the scoring you did when u use 500 grit is ok. Id be more concerned about the 2 carbon impurities in piston to...
would you think itís ok to run? Or is it damaged really badly now?
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Old 01-06-2021, 12:22 PM
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What oil do you use?
Personally i run Castor 927 at 28:1 in a stock engine, and 32:1 in my OBR. Very clean burning oil
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Old 01-06-2021, 12:28 PM
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Old 01-06-2021, 01:03 PM
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Originally Posted by gavsta72 View Post
What oil do you use?
Personally i run Castor 927 at 28:1 in a stock engine, and 32:1 in my OBR. Very clean burning oil
I run royal purple mixed 28:1
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Old 01-06-2021, 01:04 PM
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Originally Posted by the rc guy View Post
so do you think this was via oil or your doing?. I think this was a manufacturing defect when aluminum was made... this looks fine id replace that piston but I don't run fossil fuel stuff only full sized things. seen spark plug damage look way worse ran for years after then seen les blow.you make call
no this was not the oils doing, I had lots of carbon on top of the piston, so I sanded the carbon off with 500 grit sand paper that had 2 stroke oil on it.
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Old 01-06-2021, 01:09 PM
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Originally Posted by gavsta72 View Post
What oil do you use?
Personally i run Castor 927 at 28:1 in a stock engine, and 32:1 in my OBR. Very clean burning oil
Iím gonna switch to klotz benol soon, I like castor oil better than synthetic oil, seems to protect better
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Old 01-06-2021, 02:37 PM
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Old 01-06-2021, 02:50 PM
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Originally Posted by the rc guy View Post
with that defect in cylinder head you'll always get carbon build up..
so would you say itís okay to just run it?
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Old 01-06-2021, 11:33 PM
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100% This is nothing to worry about, like at all... Think about it for a sec, what could those minor sand marks do to mess up fuel/air flow. As long as there are no finger nail deep scratches in the cylinder wall or big chips taken from piston edges there is nothing to impede fuel/air movement or lower compression. Run it and enjoy the fact you just saved by extending the life of your motor.

In the future, a little brake cleaner and microfiber cloth should be able to remove any carbon build up.
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Old 01-06-2021, 11:38 PM
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Originally Posted by Lone Racer View Post
100% This is nothing to worry about, like at all... Think about it for a sec, what could those minor sand marks do to mess up fuel/air flow. As long as there are no finger nail deep scratches in the cylinder wall or big chips taken from piston edges there is nothing to impede fuel/air movement or lower compression. Run it and enjoy the fact you just saved by extending the life of your motor.

In the future, a little brake cleaner and microfiber cloth should be able to remove any carbon build up.
phew, thatís good to hear, I am currently in the process of putting a new piston ring on the engine, anything I should look out for?
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Old 01-06-2021, 11:57 PM
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Just make sure the ring is on correctly. The two ends should meet and sit on that little pin/knub in the piston collar (or whatever it's called). The arrow on top of piston should be facing the exhaust. Other than that pretty simple just make sure to clean all that old gasket material before you tighten it down and use blue locktite on the head bolts.
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Old 01-06-2021, 11:59 PM
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Originally Posted by Lone Racer View Post
Just make sure the ring is on correctly. The two ends should meet and sit on that little pin/knub in the piston collar (or whatever it's called). The arrow on top of piston should be facing the exhaust. Other than that pretty simple just make sure to clean all that old gasket material before you tighten it down and use blue locktite on the head bolts.
how would you reccomend I get the gasket material off, I got some of it off with a wet microfiber towel, should I just keep doing that?
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Old 01-07-2021, 12:40 AM
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Razor blade. Just try not to get any inside the crankcase.
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