Bike is slow to drop to idle - Page 2 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #11 of 24 (permalink) Old 05-18-2010, 01:02 PM
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Yes, it could also be leaking diaphrams. (I hate CV carbs) The part between the carb and the engine is called the manifold. It is supposed to be air tight, and completely sealed on both ends. If gas is leaking out, air could also leak in. The gas leak could have been caused by sticking floats on needle valves not sealing well, which could have corrected themselves with use. There might still be a small problem, or it might just be leaking gas when the choke is on at startup. But in any event, you have an air leak between at least the rear carburetor and head, which can cause all sorts of running problems. You can tighten the clamps and see if that helps, if not, you will probably have to replace the manifold.


As for the carbs themselves, before pulling them off and taking them apart ( taking them apart is easy, removing and reinstalling them is very tedious), try draining the gas out of them, disconnecting the fuel lines at the petcock, filling the carbs up with Seafoam through the fuel lines, and letting them soak for 24 hours. This might get rid of any remaining gunk in there that could be interfering with the floats, needle valves, and jets. It's worth a shot before pulling the carbs. Jerry.

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post #12 of 24 (permalink) Old 05-20-2010, 03:21 PM Thread Starter
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Heres an update:

I was riding down the highway with the engine completely up to normal operating temperature, when all of the sudden I started losing power. The Tach started bouncing up and down and the bike was lurching. I immediately took the first exit I could and the problem seemed to go away, it was idling fine too. Later (about ten minutes) I was slowing down to at a stop light when the engine died while it was still at about 2000 RPMs. Also, it is still very slow to lose RPMs if I pull the clutch out as I come up to a stop. The entire ride home the bike was not running right and the tach needle and engine seemed to be all over the place.

I tried looking for the plugs that cover the screws but couldn't seem to find them. What side of the bike are they on exactly?

I hope this helps narrow down my problem. Could it be vapor lock? I did fill up on gas before the engine warmed up.

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post #13 of 24 (permalink) Old 05-20-2010, 03:29 PM
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The tin plugs are from the factory, sealing the air mix screws that are located next to the vacuum ports, one on the outside of each carb. In other words, there's one on the left side of the bike and one on the right, located on the visible side of each carb. If the plugs have been removed, then you'll see the small brass air mix screw ends with a slot in them for a screwdriver to adjust them.

If your tach was bouncing around while the issue showed up, I would check your front coil connections, or your ignition switch for something loose. I don't think the fast idle problem is necessarily related to the stumbling engine issues you experienced in your last post. Hard to say, but I feel like it is two different issues.

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post #14 of 24 (permalink) Old 05-20-2010, 05:59 PM
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Originally Posted by VulcRider24 View Post
Do you think a carb overhaul is in order?



Yes, I do

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post #15 of 24 (permalink) Old 06-03-2010, 02:24 AM Thread Starter
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Took my bike to a trusted mechanic. His first diagnosis is that my low idle jet is clogged, which makes perfect sense. When my bike would start acting up, a vacuum was created in the carbs where it shouldn't be which caused my bike to fire on one cylinder. This could explain why my bike would be so slow to drop to idle, why it was sporadic, and why it would lose power at random times.

My mechanic will be pulling the carbs, cleaning them, and checking for other mechanical issues (I'm keeping my fingers crossed lol).

If any of your BS detectors went off on any of this initial diagnosis, please come forward. My mechanic was a certified Car Mechanic but got out of the field because he likes working on bikes much more. He mainly only works on friend's bikes and I have heard outstanding reviews of his abilities. I'll be sure to keep you posted on progress and thank you for all of your help thus far.

1994 Kawasaki Vulcan 750 named Jinba Ittai (Japanese for "Horse and rider in perfect harmony").
Jardine Pipes
Splines Lubricated
Painted Instrument Bezels
Headlight Visor
Chrome engine guard
Leather Fork Bag (contents: Pressure gauge, tools, and a Book of Psalms)
Yuaso MF AGM Motocross battery
Kenda Kruz Front tire
Duro Boulevard rear tire

"Buy the ticket, take the ride."
-Hunter S. Thompson
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post #16 of 24 (permalink) Old 06-03-2010, 03:39 AM
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I recommend seafoam frequently as a preventative measure.

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"To strive, to seek, to find, not to yield."
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post #17 of 24 (permalink) Old 06-05-2010, 07:03 PM Thread Starter
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Ok, my wrench pulled and cleaned the Carbs and found them to be spotless and in perfect working order. His next suggestion is that it may be by Cam chains. Could my tensioners have crapped out? I do not notice any knocking whatsoever when the bike is running. Could this be that? Or could it be Electrical? My bike has over 25,000 on it, is my stator finally going?

1994 Kawasaki Vulcan 750 named Jinba Ittai (Japanese for "Horse and rider in perfect harmony").
Jardine Pipes
Splines Lubricated
Painted Instrument Bezels
Headlight Visor
Chrome engine guard
Leather Fork Bag (contents: Pressure gauge, tools, and a Book of Psalms)
Yuaso MF AGM Motocross battery
Kenda Kruz Front tire
Duro Boulevard rear tire

"Buy the ticket, take the ride."
-Hunter S. Thompson
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post #18 of 24 (permalink) Old 06-05-2010, 07:24 PM
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Get a New Wrench that knows what he's doing..........This one is just shooting in the Dark and will have your Bike in More Problems & $$$$$$$$,
And still not have Your Bike Fixed.

Quote:
Originally Posted by VulcRider24 View Post
Ok, my wrench pulled and cleaned the Carbs and found them to be spotless and in perfect working order. His next suggestion is that it may be by Cam chains. Could my tensioners have crapped out? I do not notice any knocking whatsoever when the bike is running. Could this be that? Or could it be Electrical? My bike has over 25,000 on it, is my stator finally going?

JaY



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post #19 of 24 (permalink) Old 06-05-2010, 07:27 PM
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You can do a search for stator test or check here on the forum and get the procedure. Believe it's also in the service manuals.

I'm keepin' all the left over parts. I'm gonna use 'em to build another bike!
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post #20 of 24 (permalink) Old 06-05-2010, 07:32 PM Thread Starter
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Is it very common for the Cam Chain to fail or slip on our bikes?

1994 Kawasaki Vulcan 750 named Jinba Ittai (Japanese for "Horse and rider in perfect harmony").
Jardine Pipes
Splines Lubricated
Painted Instrument Bezels
Headlight Visor
Chrome engine guard
Leather Fork Bag (contents: Pressure gauge, tools, and a Book of Psalms)
Yuaso MF AGM Motocross battery
Kenda Kruz Front tire
Duro Boulevard rear tire

"Buy the ticket, take the ride."
-Hunter S. Thompson
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