Hard start when hot - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 34 (permalink) Old 09-08-2016, 09:51 PM Thread Starter
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Hard start when hot

Starts like a champ when cold. Pretty much will run the battery down trying to start it when it's got any heat in the motor, doesn't have to be even halfway normal operating temperature.

What all do I need to check to eliminate the won't start when hot issue?


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post #2 of 34 (permalink) Old 09-08-2016, 10:54 PM
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Originally Posted by One1 View Post
Starts like a champ when cold. Pretty much will run the battery down trying to start it when it's got any heat in the motor, doesn't have to be even halfway normal operating temperature.

What all do I need to check to eliminate the won't start when hot issue?
1. Make sure that everything is to specs
2. AGM battery - 210 CCA
3. NGK Iridium spark plugs
4. K&N drop in air filters

Starts on first push of starter for almost 9 years now.


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post #3 of 34 (permalink) Old 09-08-2016, 11:59 PM Thread Starter
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Great but that's already done and we're talking about my bike so I'm thinking more the EGR system let me get a check list from somebody


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post #4 of 34 (permalink) Old 09-09-2016, 08:27 AM
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if you ride, then let sit for a few (10-15) mins and it starts normally, look into the pickup coil mod. solves many warm/hot start issues

and of course, that listed above too!
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post #5 of 34 (permalink) Old 09-09-2016, 08:59 AM
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No throttle. If it's been parked 5-10 min., use the choke. Works on mine. If I open the throttle, backfire and no start every time.
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post #6 of 34 (permalink) Old 09-09-2016, 08:26 PM Thread Starter
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I'm leaning towards the ignition coils since the engine doesn't have to be warmed TOO MUCH before it starts getting harder to start. The coils heat up faster than the engine does so it's possible.


1981 KZ750
1988 Vulcan VN750 (red)
2005 Vulcan VN750 (silver)
(2) 1994 Vulcan VN750 (red)

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post #7 of 34 (permalink) Old 09-10-2016, 03:27 PM Thread Starter
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Well hell, Did the ign coils mod with a relay and fuse and didn't help. Onto other things. Keep the suggestions coming.

Suspecting the petcock could be leaking into the chambers, I turned it off when I got off the bike to see if that could be an issue and it wasn't affected. Still hard to nearly impossible to start when warm.






1981 KZ750
1988 Vulcan VN750 (red)
2005 Vulcan VN750 (silver)
(2) 1994 Vulcan VN750 (red)

Engineering solutions for the VN750 Community.

Last edited by One1; 09-10-2016 at 03:29 PM.
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post #8 of 34 (permalink) Old 09-10-2016, 04:12 PM
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Nice pictures of a clean job.
Have you pulled a plug to check the quality of the spark when hot?
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post #9 of 34 (permalink) Old 09-10-2016, 06:58 PM
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Run it for a bit, then pull the petcock vac off at the carb and see if it's wet. If it happens to be wet, gas in the oil is also a concern.

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__________________________________________________ ____________
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post #10 of 34 (permalink) Old 09-10-2016, 07:19 PM Thread Starter
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Nevermind. The engine just hydrolocked trying to start. It's the floats.




1981 KZ750
1988 Vulcan VN750 (red)
2005 Vulcan VN750 (silver)
(2) 1994 Vulcan VN750 (red)

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