Ox66 200 cylinder pictures help?

rjcamel2355

Petty Officer 1st Class
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Apr 22, 2015
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Hey guys. I got a endoscope off eBay and took some cylinder pictures of this 98 ox66 200 I have. Can anyone look at these and tell me if it's something to worry about? It looks like a lot of carbon on the piston to me and there's a few spots that looks like carbon has flaked off. Anyone with hints tips or anything please chime in. I've been thinking about having my injectors checked and recalibrated. I'm sure it's never been done. Pictures are at the link
 

robert graham

Admiral
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Apr 16, 2009
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6,908
Carbon on piston crowns but I'd be more concerned with possible carbon stuck piston rings....if motor runs O.K. then you can run some de-carbon through the system...several de-carbon procedures described on here. Maybe some Ringfree at carbon removal dosage. A compression test on each cylinder should give you some idea about stuck rings.
 

rjcamel2355

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Apr 22, 2015
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Engine runs excellent. Reaches wot no problem and it never coughs sputters or has any issue starting. Compression test engine cole throttle in neutral all plugs out in 65 degree weather is 100psi across the board (cheap China gauge) I know that's not the correct compression procedure but I just wanted to get an idea of it. I think the engine is fine but that looked like an awful lot of carbon to me. Is it a good idea to still have the injectors done?
 

99yam40

Fleet Admiral
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Sep 7, 2008
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9,116
they make stuff to remove carbon from motors
run some thru it
then recheck compression
 

rjcamel2355

Petty Officer 1st Class
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Apr 22, 2015
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Seafoam and 3/4 gallon of gasoline debunks method is what I always used on my mercury. I guess that's the route to pursue for this efi also
 

99yam40

Fleet Admiral
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Sep 7, 2008
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9,116
Ring free maybe in shock dose
or the Yamaha internal engine cleaner, but that is only Yamaha deal use
 

rjcamel2355

Petty Officer 1st Class
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Apr 22, 2015
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221
Did a decarb on it haven't ran the compression again yet but I did run the scope back in it. I couldn't notice much of a difference. But the link is of the pictures of it smoking like a train. So surely some of the carbon is gone. As I mentioned before engine runs great. No hiccups easy to start runs out extremely well. I've changed the plugs and cleaned the o2 sensor. The sniffer tube was clear but had carbon on the outside of it. When I got the engine from the previous owner I checked the oil linkage and it was still set for the breakin period. Is it possible that extra oil led to this carbon buildup? I just don't wanna ruin a motor over carbon. Or something I could prevent.

Thank you for the input
 
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