lost of power 81 kz 650

(81 kz 650) today i was getting on the highway and it felt like i lost a cylinder. dont know if is a carb issue. bike didnt run rough after but it did sound diffrent in the exhaust like it was not so loud anymore and couldnt go faster the 70 with the throtal wide open. norally it will power right thru 70 any guesses has brand new pluggs in it aready. thanks

Original ignition coils and sparkplug caps? They are 30 years old! Past time to replace them. While you're at it get new sparkplug wires. 7mm sparkplug wires from www.z1enterprises.com fit most aftermarket ignition coils.

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before you start changing things see if your actually getting fire,first through wires then through plugs

And if you can get it running spit or spray water on each each of the exhaust pipe near rthe cylinder head. If a cylinder is firing the water will sizzle right off immediately.

I am not a believer in throwwing parts at a problem until problem goes away. Much better to identify where the issues is . First check to see if you are getting fire and if each plug is sparking. Remove spark plugs from cyclinder. With plug still in plug cap rest so that the threaded section of the plug is touching anywhere on the engine. Hit starter button and see spark. Blue is good, yellow poor and no spark is bad.

good luck