Shocking driving and high irregular idles - Page 5 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
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post #41 of 47 (permalink) Old 07-08-2019, 06:51 PM
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I still favor an air leak somewhere. Spark and gas variations will not make RPM's rise unless there is increased airflow.

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post #42 of 47 (permalink) Old 07-08-2019, 10:12 PM
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I tend to think so too, except we've gone from revs spiking at idle, to erratic revs when throttled, to now erratic and un-driveable at any rpm.

Edit: You might go back and try the spray test again, using something flammable this time.

Starting fluid, unlit propane torch, carb cleaner (but not brake cleaner).

If you do use propane, do it quickly to avoid gas buildup, but be sure to go all around the sealing areas.

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__________________________________________________ ____________
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post #43 of 47 (permalink) Old 07-09-2019, 12:49 AM Thread Starter
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Will airleaks for this problem only occur inside the carb upto the connection with the engine? If that's the case I might further inspect the carbs to see if I missed anything now that their out

Edit: I did found out that the rubber seal in the petcock has had its time, it continuesly let's out gas. Could this be the problem? With the seal I mean the one that let's through gas if a vacuum pulls on it (the middle tube from the petcock) , that one now let's through gasoline even without a vacuum(the seal)

It's not leaking the seal is just in a state of always vacuum if u know what I mean.

Last edited by Panarock; 07-09-2019 at 12:52 PM.
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post #44 of 47 (permalink) Old 07-14-2019, 02:39 PM Thread Starter
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I tend to think so too, except we've gone from revs spiking at idle, to erratic revs when throttled, to now erratic and un-driveable at any rpm.

Edit: You might go back and try the spray test again, using something flammable this time.

Starting fluid, unlit propane torch, carb cleaner (but not brake cleaner).

If you do use propane, do it quickly to avoid gas buildup, but be sure to go all around the sealing areas.
I opened my carb and saw gas in this piece its part of the rear carb. Is this suppose to be a vacuum? Or should gas be in here? The front one was dry and never seen gas in there.
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post #45 of 47 (permalink) Old 07-15-2019, 08:47 AM
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I opened my carb and saw gas in this piece its part of the rear carb. Is this suppose to be a vacuum? Or should gas be in here? The front one was dry and never seen gas in there.

That's the coast enricher. I don't think there should be gas on that side of the diaphragm. It works off vacuum, the diaphragm opens a port on the inside and allows a small amount of fuel into the mixture on deceleration. Could be it's leaking through the diaphragm. Could be the source of the air leak too.

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 #46 of 47 (permalink) Old 07-15-2019, 04:45 PM Thread Starter
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Quote:
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Quote:
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I opened my carb and saw gas in this piece its part of the rear carb. Is this suppose to be a vacuum? Or should gas be in here? The front one was dry and never seen gas in there.

That's the coast enricher. I don't think there should be gas on that side of the diaphragm. It works off vacuum, the diaphragm opens a port on the inside and allows a small amount of fuel into the mixture on deceleration. Could be it's leaking through the diaphragm. Could be the source of the air leak too.
I ordered some parts for repair, last thing I'd want some advice on. If the petcock vacuum seal is broken could that also cause the air leak?
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post #47 of 47 (permalink) Old 07-15-2019, 09:45 PM
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I ordered some parts for repair, last thing I'd want some advice on. If the petcock vacuum seal is broken could that also cause the air leak?
It's possible, but the most usual problem is gas flowing through the vacuum line into the carb. It makes the mixture rich, and keeps flowing even with the petcock and engine turned off, then it fills the crankcase with gas.

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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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