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I know that a very vigorous crank is required to start these bikes. I generally use my 100 amp load tester to test my batteries. However I'm thinking that would melt our little batteries. What type of load should I test with?
 

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I always just gave the battery a good charge, then installed it, connected a voltmeter to it, and used the starter as a load. Watch the voltage drop as the starter turns the motor over. If it quickly drops below 10 volts, the battery is no good.
 

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Discussion Starter #3
That makes sense. Although a weak starter will also result in good voltages held.

-Robert

I always just gave the battery a good charge, then installed it, connected a voltmeter to it, and used the starter as a load. Watch the voltage drop as the starter turns the motor over. If it quickly drops below 10 volts, the battery is no good.
 

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That's true. You can check the amp draw on the starter, and see what it is. I don't know what it is supposed to be, but it should be in the manual. I personally believe the Vulcan 750 has bot a too small battery, and a too weak starter to begin with. Both my Vulcan 750s have turned over noticeably slower than most of my other bikes, even when new. But, they are also the only v-twins I have ever owned until getting a Harley Road King. It too turns over fairly slow. Could be just a v-twin thing. My recent 500 Ninja would turn over really fast, as does my 250 Rebel and 1200 Goldwing. I can't help but think that the Vulcan 750s slow cranking speed has something to do with it sometimes being hard to start. It may not be turning over fast enough to have a good spark.
 

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Your best bet is to take it to any auto parts store for FREE testing. They can compare the CCA's of the battery to what it is rated at.

When we were having starting problems with our 1990, I took our battery (which the previous owner said was NEW) in for testing, and it actually tested higher amps than it was rated at, ruling out the battery as the problem.


-Ric
 

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I know that a very vigorous crank is required to start these bikes. I generally use my 100 amp load tester to test my batteries. However I'm thinking that would melt our little batteries. What type of load should I test with?
Before purchasing my VN750 I mined this forum for the pros and cons, know issues and general information. Unanimous was the consensus that a strong AGM type battery was the best solution for many of the bikes starting problems (especially when warm). Many thanks to everyone here! So, the first thing I did when I purchased my VN750 was to replace the O.E. wet battery with a good AGM battery (Yuasa brand). That solved the endless crank to start the engine (especially when the engine was warm). Since then I've added Iridium spark plugs and K&N air filters (again thanks to the recommendations and help from this forum). Near instant starts now when the engine is warm and maybe up to 3 cranks when cold. Going on 4 years now and everything is still going strong, no starting issues, no performance issues and no battery issues. I am a convert that a really good AGM battery is a requirement for this bike. So, I would say replace your current battery if; it is more than a few years old, China made, not AGM, completely drained in the past, suspect in any way, etc.
 

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A rule of thumb is engines always start WAY better warm/hot than cold. If not, then something is definitely anominal with said engine.


-Ric
 

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Not necessarily. My baby starts right up when cold (although in Florida cold isn't that cold!) with the choke on full, but starting up when warm the choke must be off and it always seems to hesitate just a bit. Always starts up though, except for the rare POOGS issue.
 

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Discussion Starter #9
Autoparts store says they don't have anyway to test motorcycle batteries. Their load testers probably work off 100-150CCA. I have a load tester myself but its min is 100CCA, likely enough to cook these little batteries.

-Robert

Your best bet is to take it to any auto parts store for FREE testing. They can compare the CCA's of the battery to what it is rated at.
 

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Vulcan 750s almost always start easier when cold than when hot. Nobody has yet found a for sure answer as to why, it is just a quirk with this bike. Since it seems to apply to most of them, it is likely a design issue. Mine fires right up on full choke in well below freezing temperatures, but can be a little fussy to get started after being shut off for 10-15 minutes.

As far as battery testing, I have a number of bikes, and if I charge the battery 24 hours at 1 amp, and hook it up to another bike with a known good starter, and it goes dead after turning the engine over a few times, it's a bad battery. A good battery load tester will tell you the actual condition of the battery compared to new, but if the battery is toast, you don't need to be that accurate to figure out what the problem is.
 
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