Ignition Coil or Carbs or Plugs?

[vintagevantage]

I have a 1977 Kawasaki KZ750B twin.

Its been acting funny, so i replaced the plugs. About 5 years ago I changed the coils so they have about 6k miles on them

Bike was running weird so I changed the plugs and took it on a long run. Left cylinder plug still looked brand new. Right cylinder plug was not fouled, but much darker than new.

Im going to get into the bike this weekend, but have a superficial question: would a failing ignition coil result in one cylinder not firing properly and causing the bike to run poorly?

 

[pidjones]

Left side plug looking new sounds like that side is very lean.

 

[vintagevantage]

Left side plug looking new sounds like that side is very lean.

Thanks for responding, but your reply doesnt make sense.Both plugs are brand new. Im more concerned about why of the two brand new plugs I put in,and rode 5 miles on, one is dark but not fouled. while the other looks normal.

 

[Streetfighterkz]

Can you post pics of the plugs?

Later, Doug

 

[vintagevantage]

Can you post pics of the plugs?

Later, Doug

I think i found the problem. vacuum leak. my twin shakes a lot and the cylinder cover was not properly tightened down. just took the bike for a run after tightening it up, and it seems ok. held idle well

 

[pidjones]

>took it on a long run. Left cylinder plug still looked brand new. Right cylinder plug was not fouled, but much darker than new.<
Sorry, but it does make sense, given your statement.

 

[benroloff]

I understood what pid meant, but for the sake of clarity, he is trying to say that a plug that still looks new after being run for a while(this is what your reporting) is a telltale sign of that cylinder being lean, a carburetor issue.


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