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One cylinder not firing

19K views 18 replies 5 participants last post by  Furrryteddy 
I ran into a bit of an odd problem this weekend. My #1 cylinder isn't firing. It's just shooting the unburned fuel out the exhaust. I switched plugs with another cylinder and it still did it. The coil runs another cylinder that's also working just fine. I'm baffled by this one. It's a Yamaha XJ650.
If anyone is still looking for a possible solution to 1 or 2 cylinders not firing one possible solution is a Vaccum leak. I confirmed this as I had the same issue. I removed the airbox, placed my hand over each opening of each carb, and the one not running was able to suck in fuel and fired right up. I also sprayed some carb cleaner on each boot and wahlah, fired right up. I will be purchasing 4 new boots and will post results. In conclusion, check for a Vaccum leak. All I see is replace the coils, clean the carbs for the 8th time, replace spark plugs, compression, plugs blah blah blah etc. Etc. Could be an easy fix with new boots.
 
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