Hard Starting- Especially When Warm- Long Post - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 12 (permalink) Old 09-25-2013, 08:07 PM Thread Starter
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Hard Starting- Especially When Warm- Long Post

New to me '89 Vulcan with 18K miles. Driven it about 300 miles with the only issue being almost impossible to start when warm. To start when cold, I need to hit starter with "choke" off and soon as it fires, quick put on choke. Warms up OK and eventually runs fine without choke.
Took an uneventful 50 mile ride today in superb weather. Gas got low and as it sputtered, I did not get it onto reserve fast enough. Tried staring until battery wore down. Called son to bring truck and just as we went to load it started on reserve. Got home OK after stopping for gas.
Here's the question: Soon to go into the basement for winter. Don't mind pulling this apart if there is something I can address on the carbs. Any recommendations on things to chase or modify?
Great to be back in a saddle again after 4 years off. Tim
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post #2 of 12 (permalink) Old 09-25-2013, 08:22 PM
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Your hard starts are likely due to a weak battery. Most folks here reccomend an AGM battery (Absorbed Glass Mat) costs twice as a regular wet cell but solves several issues along with hot starting problems.

If you're going to store the bike, I suggest fiiling the tank and pouring a half can of SeaFoam in the tank, go for a short ride then come back, change the oil+filter then park the bike.

Cover the bike with a sheet and put a can of mothballs under it (keeps bugs out)

There's debate on if you should drain the carbs...I'll let you make the call on that.
Spend the winter reading every thread on this forum....

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post #3 of 12 (permalink) Old 09-26-2013, 11:21 AM
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I ran mine completely out of gas on the main pickup and it took some time before it would fire up. I eventually pushed it to level ground, not sure if that helped but it finally fired up. Really thought I was going to be walking home.

Have to bear in mind, it takes vacuum to open the petcock, so in this case, you'll only get fuel flow when it's cranking.

On hot starts, my bike refuses to start if I even slightly open the throttle. Hard habit to break and it catches me pretty often. Let go of the throttle and fires right up. Might see if yours is the same way.

Battery condition does mean a lot on these bikes. Left my switch on for two hours the other day and ran the new AGM battery dead. It finally started but didn't want to, and it wouldn't run well above 4000 rpm on the ride home. It backfired while starting and if I tried to go too fast. It's all back to normal now after some time on the trickle charger. I did the headlight bypass so all my lights are on as soon as the switch is on, need to change it back.

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post #4 of 12 (permalink) Old 09-26-2013, 11:46 AM
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I rebuilt my starter and the hot start problem solved. I have an extra starter that I purchased before I rebuilt the old one. Belonged to a member here. Looks to be in good shape if you want it. $75

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post #5 of 12 (permalink) Old 09-26-2013, 01:23 PM Thread Starter
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Starter is fine

Bike cranks over fine, hot or cold. Just will not fire when warm. Let it sit awhile, come back and starts right up.
Very annoying.
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post #6 of 12 (permalink) Old 09-26-2013, 02:06 PM
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AGM Battery

X 2 on what Knifemaker says. You will be surprised what difference the battery will make. Does it backfire while cranking it? A couple years ago I was having trouble with hot starts, I changed the battery and couldn't believe the difference. I too thought my battery was cranking well hot or cold.


New to me 2004 15k Last liscened in 2011. Stock as they come.
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post #7 of 12 (permalink) Old 09-26-2013, 06:56 PM Thread Starter
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Thanks Folks

Will take your advice and start the spring with a new battery.
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post #8 of 12 (permalink) Old 09-26-2013, 07:04 PM
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Tim....check into the Northeast regional section here for group rides and get togethers....

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post #9 of 12 (permalink) Old 09-26-2013, 07:29 PM
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hot starts problems are common on these bikes i did the pick up coil mod and it worked wonders

and the way you describe your cold starts i would recomend that you give the carbs a good cleaning this winter

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post #10 of 12 (permalink) Old 10-02-2013, 12:22 PM
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I have the same issue, and it's not the battery for me. Haven't pin-point the issue yet though. Going to try a few things this weekend.

If you want a new AGM battery, I got one from Advance Auto:

Use code MFD13 for $20 off $60.
Or TRT41 for $40 off $100 if you want to spend a few more dollars.
TRT37 for $25 off $75, which is perfect for this battery. $10 core charges and you'll be spending about $55.
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