Sputtering at high temp - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 2 (permalink) Old 07-20-2018, 04:31 PM Thread Starter
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Sputtering at high temp

I've had this 95' vn750 for a few weeks now. It's got 54k miles on it so I assume it's been through some stuff.

The problem I've been having recently is once the bike gets hot it starts sputtering at higher RPMs and will stall out.

I want to start out by saying I definitely feel like it's running rich. I can smell it. Also in the past few weeks I've had issues going places and having a hard time starting it back up. I have to use full choke to get it started back up. The bike has custom ear shaved exhaust and I'm not sure if the previous owner re-jetted for this but I want to assume they have since it has so many miles on it.

I don't know much about the coaster thing I'm reading about in these forums. I did do the pick up coil mod the other day to help with hot starts.

I have a manometer and plan on attempting to sync the carbs too. I believe the front cylinder is running really rich and the rear cylinder is running really lean. I feel like this could be the source of my problem.

Again the problem is when the bike gets hot it will begin to idle erratically (jump up in rpms) and then when I hit higher rpms in gear it starts to sputter, slip, and stall out. It has no problems idling when starting it up cool. The problem only arises after riding for 20-30 minutes.

I'll take any advice I can get! If anybody has any ideas to what could be the cause of this issue.

Thanks guys!
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post #2 of 2 (permalink) Old 07-20-2018, 07:26 PM
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Ignition coils can sometimes break down under heat, or if there are cracks, the cracks become wider with heat. You could run it in the dark and look for arcing, just found one of my plug caps arcing to the head. Look at the coils, plug wires, and plug caps.

Since it's earshaved (intake mod), find out where the carb vents are running to. They need to be out of the wind.

Check for air leaks around the carb boots.

Read about POOGS on the site and decide if that could be the problem.

Make sure there's no gas in the petcock vacuum line from the left carb after running a short time. It should always be dry. Extra fuel can get to the front cylinder if the line is wet.

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