Hard to start - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 17 (permalink) Old 02-14-2020, 02:17 PM Thread Starter
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Hard to start

So when I try to start after riding maybe an hr or getting gas,its hard to start back up.sometimes I need to give it full throttle for it to start n someti.es not.the carbs have been set to spec's and a lil adjusted.ive tried everything.i replaced one air cut of value. About to order other side.but I'm at dead end now.ive cleaned carbs not to long ago.ive fixed all vacuum lines.can someone help me before I put money then it's worth to put it in a shop.thanks
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post #2 of 17 (permalink) Old 02-14-2020, 02:47 PM
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Usually have to use the choke on mine after a gas stop.

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post #3 of 17 (permalink) Old 02-14-2020, 05:09 PM Thread Starter
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Mines even goes into a vapor lock at times
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post #4 of 17 (permalink) Old 02-14-2020, 06:12 PM
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The owners manual states that when the bike is hot, no choke, throttle open half way. If the engine is flooded, full throttle while trying to start, and if cold open choke with no throttle. If you’re doing all these right then there is a pickup coil mod that is supposed to improve hot starting. It’s an electrical issue not a carb issue and apparently pretty common on these bikes.

The mod and how to do it is fully covered here on the site. You can search on the details. The other thing could be the battery. Make sure it’s a strong battery. AGM type work much better than the wet cell.
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post #5 of 17 (permalink) Old 02-14-2020, 07:05 PM
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Quote:
Originally Posted by mmart View Post
The owners manual states that when the bike is hot, no choke, ....
But they cool off really quick.

If I open the throttle instead of the choke after a gas stop, it just backfires.

Now, if I use my card at the pump instead of visiting the cashier and lotto scratchers, it starts right up.

2003-21k mi
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__________________________________________________ ____________
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Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #6 of 17 (permalink) Old 02-14-2020, 11:10 PM
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Ha, I normally don’t even get off the bike when I fuel up. But the one thing I’ve noticed that’s consistent is the longer I ride before gassing up the harder it is to restart. But I can’t say I’ve ever used the choke other than the first fire up of the day or when it’s been sitting in the cold for a while.
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post #7 of 17 (permalink) Old 02-15-2020, 11:21 AM
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Quote:
Originally Posted by mmart View Post
Ha, I normally donít even get off the bike when I fuel up. But the one thing Iíve noticed thatís consistent is the longer I ride before gassing up the harder it is to restart. But I canít say Iíve ever used the choke other than the first fire up of the day or when itís been sitting in the cold for a while.
Is your bike earshaved and re-jetted? Thinking it might be toward the rich side, not a lot but enough that opening the throttle works.

Every other bike I've had needed some throttle for a hot start, so it took a while to break the habit. People tend to freak out when it backfires at the pumps. Also took a while to believe it needed the choke after the relatively short stop. But it fires first time with the choke and no throttle.

I finally began just using my card at the pump, it's the best way to get the tank full without guessing at the amount or going back in to get change. Also don't have to put it on the centerstand, just straddle the bike upright and filler'up.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #8 of 17 (permalink) Old 02-15-2020, 12:24 PM
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My bike is stock, at least as far as the air filters etc. I have no clue if the PO did anything. It wasn’t a private sale I bought it at an HD dealer near me. I’m sure their intention was to just move the bike off their lot. The guy said “we don’t work on jap bikes”. The price was good for my first bike so I took it. I have never had it backfire at the pump as loud as it did when I had a weak battery in it. It sounded like a shot gun!! But to be honest the hot starts aren’t really that big of a deal, at least not as bad as some people have stated. Sometimes it feels like it starts before I even take my finger off the starter.
As far as putting it on the center stand, I’ll shamefully admit that I haven’t been able to do it yet lol. I know it’s a technique thing and I’ve only tried a few times in front of the house and since my pavement isn’t very level it feels like I could easily drop it so I haven’t bothered.
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post #9 of 17 (permalink) Old 02-15-2020, 01:12 PM
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Quote:
Originally Posted by Alexgmb24 View Post
Mines even goes into a vapor lock at times
Do you mean the engine cranks, then stops suddenly, then cranks again?

You can check the vacuum line for the petcock to make sure it's dry after running. If gas flows through the line, it floods the front cylinder.

2003-21k mi
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__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #10 of 17 (permalink) Old 02-15-2020, 01:13 PM
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Hot starts with mine are like turning on an electric motor. Bzzt, vroom. ... as long as I don't touch the throttle. I give the AGM battery a lot of credit for that, and clean carbs.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
Repair Manual: http://www.mediafire.com/file/mj7z81..._Catalogue.pdf

Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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