Choke issue I believe - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 18 (permalink) Old 06-23-2013, 09:07 AM Thread Starter
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Choke issue I believe

Hi,
When I try start my bike using the choke set to maximum, the bike engine turns and turns but the bike doesn't start. Sometimes it will even back fire through the right exhaust. If it is warm enough outside and I try to start without the choke the bike may start but sometimes doesn't maintain it's running status and stall. With repeated restarts the bike eventually will maintain the engine running. Once the bike has been running for a while, it will run well for the entire journey.
This problem started a couple of years ago when I was away on a government assignment for a little over a year and when I got back the bike had carburetor issues. I took it to my local dealer who cleaned the carburetors and the bike once again ran. However, the choke issue began. I took it back to them last summer but, they told me there was nothing wrong with it. That was very frustrating because they aren't the people starting it in the morning. I am.
I hope someone on this site can help me with this problem. I am not very mechanically inclined so whatever detail you can provide is greatly appreciated.
Sam
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post #2 of 18 (permalink) Old 06-23-2013, 09:32 AM
..have a vulcan good day!
 
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Quote:
Originally Posted by tjssbn618 View Post
Hi,
When I try start my bike using the choke set to maximum, the bike engine turns and turns but the bike doesn't start. Sometimes it will even back fire through the right exhaust. If it is warm enough outside and I try to start without the choke the bike may start but sometimes doesn't maintain it's running status and stall. With repeated restarts the bike eventually will maintain the engine running. Once the bike has been running for a while, it will run well for the entire journey.
This problem started a couple of years ago when I was away on a government assignment for a little over a year and when I got back the bike had carburetor issues. I took it to my local dealer who cleaned the carburetors and the bike once again ran. However, the choke issue began. I took it back to them last summer but, they told me there was nothing wrong with it. That was very frustrating because they aren't the people starting it in the morning. I am.
I hope someone on this site can help me with this problem. I am not very mechanically inclined so whatever detail you can provide is greatly appreciated.
Sam
My 750 starts np w/o the choke applied, but does not idle well until warmed up.
After Start-up (w/o the choke), I pull the choke "ON" for a minute or so.

...works for me

'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
Additional Flashing LED Brake Light on Trunk
Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!
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post #3 of 18 (permalink) Old 06-23-2013, 09:34 AM
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I see it's your first post, so...

Welcome to the forums.

Sounds like they moved the dirt from the pilot jets to the enrichment jets. These carbs don't have an actual choke with a choke plate, it's called an enrichment jet. Possibly it's dirty or the plunger isn't working. Also check the cable that runs to it.

Also, wait for someone that knows these carbs in particular, I haven't had to get into mine yet.

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post #4 of 18 (permalink) Old 06-23-2013, 09:45 AM Thread Starter
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Originally Posted by Spockster View Post
I see it's your first post, so...

Welcome to the forums.

Sounds like they moved the dirt from the pilot jets to the enrichment jets. These carbs don't have an actual choke with a choke plate, it's called an enrichment jet. Possibly it's dirty or the plunger isn't working. Also check the cable that runs to it.

Also, wait for someone that knows these carbs in particular, I haven't had to get into mine yet.
Thank you for welcoming me to your forums.

After starting the bike, i can put the choke on and the engine revs higher. I have to do this slowly otherwise the bike stalls.
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post #5 of 18 (permalink) Old 06-23-2013, 10:02 AM
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Seems like a fuel flow issue somewhere. Check the volume of fuel coming from the petcock and fuel lines.

But after thinking (dangerous for me) about it, I'm wondering if it's already too rich and pulling the choke makes it worse, hence the need to pull the choke slowly.

Have you looked at the plugs to check color? Ever see any black smoke at the pipes? I'm just on the fence now if it's lean or rich.

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__________________________________________________ ____________
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post #6 of 18 (permalink) Old 06-23-2013, 10:10 AM Thread Starter
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Seems like a fuel flow issue somewhere. Check the volume of fuel coming from the petcock and fuel lines.

But after thinking (dangerous for me) about it, I'm wondering if it's already too rich and pulling the choke makes it worse, hence the need to pull the choke slowly.

Have you looked at the plugs to check color? Ever see any black smoke at the pipes? I'm just on the fence now if it's lean or rich.
There is no visible exhaust coming out of the mufflers. I also believe that it could be an already too rich fuel mixture but I have no idea how to adjust that if that should be the culprit. The crazy thing is that once the bike is warmed up, it runs like a champ. It's just trying to get it to start the first time during the day.
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post #7 of 18 (permalink) Old 06-23-2013, 11:19 AM
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I had a similar issue when I got mine.. tough to start and didnt want to keep running until warm..

one of the 2 plungers for the enrichening jets was stuck partway pulled... freed it up and no more issues..

there are 2, one on each carb. easiest one to see is on right side of the bike..
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post #8 of 18 (permalink) Old 06-23-2013, 11:22 AM
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I think we need to know how it's running (rich/lean) so we can figure where to go.

Can you look at the plugs?

You can start it cold without pulling the choke? That would mean it's rich, unless you live in Death Valley with 100 temps. But the plug color would tell us a lot.

See, I'm thinking if it's rich, you open the enrichment too quickly and it stalls from flooding out. When it finally starts under those conditions, I would expect to see at least a puff of black from one of the pipes.

This is hard to diagnose without being there, but we do it a lot here, successfully. Just have to work through it.

2003-21k mi
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__________________________________________________ ____________
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post #9 of 18 (permalink) Old 06-23-2013, 11:23 AM
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Quote:
Originally Posted by michiganteddybear View Post
I had a similar issue when I got mine.. tough to start and didnt want to keep running until warm..

one of the 2 plungers for the enrichening jets was stuck partway pulled... freed it up and no more issues..

there are 2, one on each carb. easiest one to see is on right side of the bike..
Now we're getting somewhere.

2003-21k mi
Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
__________________________________________________ ____________
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post #10 of 18 (permalink) Old 06-23-2013, 11:37 AM Thread Starter
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I just tried to start the bike. I tried to catch a few times but, never did before the battery got too low to crank. I have pulled the 4 spark plugs (hope that's all there are, i mentioned I'm very mechanically challenged). All the plugs look dry and clean. I found the two air/fuel mixture screws. Turned them all the way in and then back them out 2 full turns.

This is another thing I have noticed but, the place that did the work on my bike last told me I'm all wet. I mentioned to them that I thought I needed another battery since I only get a few tries at starting before the battery goes dead and, that when I top it off with a recharge, the bike starts much better. However, as I stated earlier, the Kawaski dealer in tiverton, ri said that isn't the issue.

What does the enrichment plunger look like? thanks for all your help. we will nail this thing or it's time to get another bike.
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