cold starts easy,starts hard when warm?? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 7 (permalink) Old 07-10-2011, 12:31 PM Thread Starter
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cold starts easy,starts hard when warm??

I can let the bike sit all night walk out in the morning hit the throttle twice push the button and it fires right up and idles perfect no once it has warmed up I can ride it to the store,3/4 of a mile away go ingrab a drink and when I come back out i have to choke it and hold the throttle wide open to get it to start....any idea what would cause this? thanks
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post #2 of 7 (permalink) Old 07-10-2011, 01:11 PM
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Most hot start issues are due to a weak battery. Do you have an AGM maintenance free battery in there?

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post #3 of 7 (permalink) Old 07-10-2011, 03:16 PM Thread Starter
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no i dont have an AGM battery yet..definately my next investment..that and the ear
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post #4 of 7 (permalink) Old 07-10-2011, 06:39 PM
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What's the idle line when it's hot before you shut her off? A little high maybe?
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post #5 of 7 (permalink) Old 07-10-2011, 11:32 PM
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Also could be the pickup coils need to be re-gapped.

Made a world of difference on mine.

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post #6 of 7 (permalink) Old 07-10-2011, 11:35 PM Thread Starter
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i believe it is around 1000rpm's
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post #7 of 7 (permalink) Old 07-11-2011, 12:09 AM
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Getting an AGM maintenence free battery is a good idea for the Vulcan 750.

If you want to do a few less expensive (and helpful) things, here are a few:

Replace the stock spark plugs with iridium plugs. Part#: NGK DPR7EIX-9
Iridium plugs provide a more concentrated spark for more energy delivered to the air/fuel mix. Pow!

Run the air/fuel mixture screws all the way in until they seat (gently). Then run them out to 2-1/2 turns.
This is regarded by most as a good starting point for the correct air/fuel mixture.

Clean and grease (dialectric) the batt(-) ground connection to the frame. Clean the batt(-) connection to the engine. Clean and grease the batt(+) connection to the starter motor in the front of the bike.
Clean and grease the stator wire bullet connections, and all R/R connectors.
This will help with good and nicely regulated charging.

Re-gap the ignition coil pick-ups to have a .020” clearance.
This mod will provide a more certain trigger to the ignition module. It theoretically advances the spark slightly, though probably negligible.

Run 3 oz. of Seafoam in a fresh tank of gas about every fourth tank.
This helps keeps those itsy-bitsy idle jet orifices clean.

These are inexpensive things you can do, and they all help the bike start and charge reliably.

Good luck.

P.S. - Go ahead and check the sync on the carbs ... never hurts.

~~C8> Ratt
'91 VN750 - Cosmic Splendor/Candy Wine
Done: Coastered, .020 ign., Iridiums, VM
Plexistar II, MCCT's, Relocated MOSFET
Next: LED's
Will Do: Horns, Shave(maybe)

Last edited by ZCraggRatt; 07-11-2011 at 12:14 AM. Reason: P.S.
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