Hot Starting issue - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 16 (permalink) Old 07-07-2010, 07:04 PM Thread Starter
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Hot Starting issue

My bike is pretty new to me (it's a 2003, just got it used with 2250 miles on it), but I'm having difficulty getting it started quickly when the engine's hot.

When it's cold, even in warm temperature outside, I give it full choke or a little less and it starts right up. I've been through a number of tanks of Gas, so not a stale gas issue.

When it's hot, such as just after you kill the engine, I have a heck of a time getting it started. If you give it no choke, it will rarely catch. Sometimes, giving it a steady quarter throttle while turning it over works with the choke off, but other times I end up giving it a little choke. It all ends up annoying when you're sitting somewhere like the gas station.

When it's warm and has been sitting 30 minutes, it's more of a guessing game.

I'm the first to admit I don't know what's normal for this bike, so I'd appreciate any feedback. Think it's just me, or do I need to do some work to the bike (and if so, what?) ?
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post #2 of 16 (permalink) Old 07-07-2010, 07:29 PM
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I have a 2005 and had the same problem, I put in a Yuasa battery and that solved the problem
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post #3 of 16 (permalink) Old 07-07-2010, 07:37 PM
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think about rebuilding your starter too. kits are available on ebay for 30ish
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post #4 of 16 (permalink) Old 07-07-2010, 07:51 PM Thread Starter
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The starter turns over plenty quick, and I have a receipt from a new battery this year. It just doesn't catch. Sometimes I'll get a backfire too.

Of course, I went out a few minutes ago after it setting for an hour and it went varroom... started right up.

Shut it down and gave it a minute, started again with a little throttle. Unfortunately, when I need it to start immediately, no dice.

I see some people are using Seafoam. I don't have any, but I just put in some Marvel Mystery Oil to see if it's a gum/varnish issue in carbs. I think not.

Last edited by roamergrg; 07-07-2010 at 07:54 PM.
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post #5 of 16 (permalink) Old 07-07-2010, 08:40 PM
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Originally Posted by roamergrg View Post
The starter turns over plenty quick, and I have a receipt from a new battery this year.
Is it a maintenance free (MF) battery? If not I go with a good MF before you go for a stator rebuild. I had the same 'hot start' problem for years on my '93. The same problem you describe, found this forum and purchased a new MF battery no problems since.

Glenn Douglas
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post #6 of 16 (permalink) Old 07-07-2010, 10:20 PM
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ok time for my 2 cents worth...

I used to have similar issues... with a normal battery, useing the choke with a little gas no matter what temp the bike is at is normal... switched over to a MF battery, and have not had an issue fact I don't even use the choke any more. also to go along with that, make sure your carbs are adjusted correctly with out the black knob adjusted all the way out... this will give you the best performance you can ask for.
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post #7 of 16 (permalink) Old 07-07-2010, 11:53 PM
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If your bike is cranking fast enough, and it should be pretty fast,Iridium plugs and setting the air gap on the ignitors made my 92 start like a new bike ,after I put a rebuilt starter I got from Crobins 365 on hereI also installed the iridium plugs but the cranking speed and the ignitor gap setting made all the difference .To see if it is a cranking issue ,ride it a while to get it good and warm and pull it over at the top of an incline and let it set about 5 minutes and then try to start it ,if it doesn't Let it roll down the incline and stick it in second gear and see if it fires right off,if it does you have a slow cranking issue and need to decide if it is the battery or the starter,I am thinking battery if you have a year old flooded wet cell battery.If not cared for IE:checking water monthly,and keeping a good float charger on it when sitting for extended periods, a year is about the life of them,Save yourself a lot of work and grief and get a Maintenance Free battery if you don't have one.After all the pushing and cranking I did on mine when it was warm I can sympathize with you.But now I don't worry it starts when I hit the button.The number one problem with mine was it just wasn't cranking fast enough,when all was said and done and current that should have been going to my coils was b eing sucked up trying to turn over the engine.

If you see it on my bike I did it
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post #8 of 16 (permalink) Old 07-08-2010, 05:54 AM
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Vulcan hot starts. Boy its a popular issue. There is a good coil fix on here for that which makes a lot of sense. These bikes wont fire good if the voltage is less than 12 volts. So, from what I have read is all true. Good battery, good starter. Even though it cranks ok it could be pulling the battery down if less than perfect which robs starting volts to the coils. Same with plugs, fresh, correct gap. Im still stymied why the damn things start cold ok. I would think its harder to crank a cold engine than a warm one, so who knows. I actually wonder if these things get a little vapor lock. The motors are really stuck in there tight and the carbs are right between the jugs.
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post #9 of 16 (permalink) Old 07-08-2010, 07:49 AM
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Hot Starts

I bought a used 94 750. It had an aftermarket exhaust on it. It also had the starting problem. I am not a loud person so I changed the exhaust system back to stock. I couldn't believe the difference it made. It starts well now. If when the exhaust system is changed the carburetor is rejetted in might be ok, but if not you will have problems. By the way I really like the bike. It is older but had had a good home and looks good and now runs good.
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post #10 of 16 (permalink) Old 07-08-2010, 11:37 AM
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ok i spoke too soon, thismorning tried to start her... took full choke and half throttle... when cold... won't start when hot at at all.. with the normal start button.. with my aux. start switch it starts right up when hot... this is a first.. my aux start swich shouldn't work at all.
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