Help with piston wash

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yamahakid88

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Joined
Feb 2, 2015
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25
Location
Illinois
Hey guys, having trouble figuring out why one cylinder looks the way it does. The 2 other cylinders I know are running rich. All 3 carbs had the same jets and settings, so im not sure why this one looks leaner

http://imgur.com/a/iGe6t
 

its richer on the pto cylinder, not leaner. Its mostly due to that cylinder has a lower compression ratio then does the center and mag cylinders. Yamaha did this so you could use the same jet in all 3 cylinders. if you look at the head youll notice the pto cylinder has a larger dome, and if you put on a compression guage it will be lower in the pto.
 
your pto piston pic is richer then the other 2 are, its more silver because the gas washes off the carbon. If it was all dry and silver with a sandblast appearance it would be leaner, but yours is richer.
 
Ok so I would need to go on the center and mag side? It has triple pipes and it was running 165 mains with 45 pilots across. Needles at stock height and 2 turns out on the screws
 
I really dont have any better pictures, I already closed it up. They are bender pipes. Will have to tear into the carbs again then. Can the needles be adjusted without taking the carbs out
 
just raise the needles a tad (1/2 spot)on the center and mag cylinder, look up needle adjustment on here theres even a thread or 2 with pics. if you have never done it before, I might suggest taking the carb rack off and doing them on a bench so you don't drop the screws and shims into the engine bay and invent new cuss words....
 
Ok, raised the needles like you said, 1/5 turns out on fuel screws, 55 pilots and 165 mains. I did not touch the needle of the pto side piston, should that be ok?
 
ya you should be good to go, take it out for a good rip and kill it and look at plugs and piston top
 
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