Uneven Fouling of Plugs. [photos]

ORIGINAL SIGBIN

ORIGINAL SIGBIN

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Good evening sirs,

My name is Reuben [XS400 1981 SOHC] from New York. I'm not rich and live far from the trains so my bike really is my only mode of transportation. Please help me out.

I've gotten new plugs 2 weeks back and just yesterday I made an 80 mile trip on the freeway going at 75 mph. The bike runs great except for when I'm at high rev and let go of the gas it pops and backfires through the EXHAUST. Another problem is when I'm taking of or in 2nd gear just barely giving it gas it also pops and backfires through the INTAKE. I have photos of both plugs here so as to not waste anyone's time. Thanks guys.
 

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Go over your routine maintenance first. Check valves, timing, carbs synced.. Are there any air leaks in your exhaust?
 
Yessir. I've done those already. And yes there is a leak on my right exhaust. But that wouldn't really come into play because it's both plugs that are looking like that. I'm so cnofused on why this is happeneing.
 
Hey, Chris. Thanks for coming to help me out again. I finished rewiring my charging and I'm now getting the porper volts. I'm running pods and stright baffles? (not really sure what the PO got there, but there are baffles in there I'm sure.) As for the carbs It is rebuilt with JBM diaphragms and new jets. Main = 142.5. All other jets are stock sizes. I couldn't change the needles because ... they looked fine and I was scared of the tiny brass screws that held it. The fuel level has is 2mm below the bowl seam.
 
Look up tube manometer on this forum. What you have there is not going to work. Your exhaust and air filter setup is not going to help with tuning also.
 
Update. It turned out to be a timing problem. My bike was somewhat retarded in spark so explains the partial fouling. I came upon a mystery screw though, on the carb. It is on both carbs right below the butterfly. Could anyone tell me what this is?
 

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It's for nothing. Just a block off plug and for stopping the throttle assembly.
 

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