Dropping a Cylinder When Hot - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 4 (permalink) Old 07-03-2017, 03:28 PM Thread Starter
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Dropping a Cylinder When Hot

I have a 2002 Vulcan 750. When the bike gets hot (not overheated) one of my cylinders stops firing. Riding 200 miles to the beach about 80 miles into the ride 65 mph about 85 degrees out side (temp gauge reading normal) my cylinder will intermittently drop out. Fuel drips out the one pipe. If I pull over let it cool for 15-20 minutes it runs fine for 30-50 miles. I rode 580 miles through the blue ridge parkway and smokey mt national park temps in the 60's and had no problems. I have been to several dealers and they want to start replacing parts because it "might be this or it might be that". Not being sure what we will run into and not wanting to replace parts that are not bad has me reluctant to spend the money to try this or that. Any thoughts?
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post #2 of 4 (permalink) Old 07-03-2017, 04:33 PM
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Fuel drips out of the pipe while it's running?

First thought is a sticking float, or float height way too high.

Have not seen heat affect a float in any way, so it may have a second problem.

A stuck intake valve would kill the cylinder and put raw fuel into the exhaust, but it seems you should hear some tapping when that occurs.

Ignition dying under heat would also cause both symptoms. I would check for spark on the dead cylinder while it's still hot.

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post #3 of 4 (permalink) Old 07-03-2017, 08:38 PM
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Another vote for ignition failure at temperature. Had a car would do that to me until I replaced the distributor pickup.

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post #4 of 4 (permalink) Old 07-08-2017, 07:38 AM
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Some say it may be the ignitor pickup gap. Mine does the same thing. If the temp runs up about 3/4 it starts misfiring. It died on me the other day. I two legged it over to the side of the road. crank, crank, nothing. I am saying to myself. I am sick of this piece of **** Vulcan thing. Ready to drop it on its side and call Uber. Crank, fires right up. WTF, So I red lined through four gears until everything was blurry. Regained my composure, got home and shut if off. Fan was running, then stopped. Hmmm? I have a New glass mat battery. Maybe just maybe the fan draws too much current as these bastid things are very dependent upon having minimum 10 volts to run! Definitely do the ignitor gap mod as these folks in here have been through it all with these bastid Vulcan as well. Strength in numbers, time is knowledge. I have had this bike for more than 10 yrs, second owner, put more miles on it than the first. Divorce is stopping me from a new bike, but these are quick little machines and fun to ride if you can put the little quirks to the side and just ride!
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