engine continues to hold rpm after releasing throttle - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 10 (permalink) Old 08-27-2010, 03:47 PM Thread Starter
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engine continues to hold rpm after releasing throttle

please help, new 93 vn750 11 k niles, new air / oil filters etc. sea foam first kawasaki when riding the rpms hold for a few seconds then di slowly even though the throttle has been released, i checked the slides they go down and real slow to go back to idle. is this the air pump system?
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post #2 of 10 (permalink) Old 08-27-2010, 04:26 PM
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Welcome to the Vulcan madness.

Where are you located shegge?
Do you know if your bike is equipted with California emmision controls or 48 state?

Go to newbie checkin and tell us a little more about you and your bike.

Also go to user cp and fill out profile, so location will show on each post.

Info about bike can go in signature line, and show up on every post too, so when you ask for help you don`t have to remind us every time the particulars, ie. California or Switzerland emissions, any modifications, etc.

The vn750 has 2 throttle cables. One to roll on throttle, and the second for a positive roll off or to decelerate.
Not sure whether or not it could cause the symptoms you describe if the roll off cable was broken.
Sounds like something else to me, but I`m no expert on carbs and emissions controls.


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Purchased May 16, 2008
Approx.19,300km (12,000 miles)

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Last edited by OlHossCanada; 08-27-2010 at 04:29 PM.
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post #3 of 10 (permalink) Old 08-27-2010, 08:25 PM
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Gordon has a good point about the cables but it sounds to me like the spring broke on the carburetor throttle adjustment arm or the diaphragms in the carbs need replacing. They are made of rubber and the air forces them up when you open the throttle but when you release those things are supposed to bring the piston holding the jet needle back down cutting down on the fuel mixture going into the cylinder. When the diaphragms get old and stretched out or even torn they don't do what they're supposed to. Worth checking out. Good luck.

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post #4 of 10 (permalink) Old 08-27-2010, 08:26 PM
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Have you anytime lately oiled the throtle cables going to the carbs. They could be gummed up and need a little lubricant. Easy fix if this is your problem.

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post #5 of 10 (permalink) Old 08-27-2010, 09:06 PM
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motion pro has a nice cable lubrication tool

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post #6 of 10 (permalink) Old 08-27-2010, 09:37 PM
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it sounds like your diaphragm on top of the carbs might have a pin hole in it...
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post #7 of 10 (permalink) Old 08-27-2010, 10:07 PM
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mine did the same thing. changed cable helped a bit. changed the read vac line and it fixed this problem

My Enuf.
1995 Vulcan 750
New wires and plugs
Removed and cleaned carbs
re routed air line to right ear
re built transmission
New stator
New RR
New throttle cables
New clutch cable
New wiring harness
New Ignition switch
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post #8 of 10 (permalink) Old 08-29-2010, 10:40 AM
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It is quite possible you have and air leak in the intake. Check the boots that hold the carbs to the cylnders, the boots that go to the air boxes and the lids of the airboxes for tightness.

My bike did this at 2000 miles and it went away after I tightend everything up.


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post #9 of 10 (permalink) Old 08-29-2010, 03:11 PM
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I was going to say lube the cable and inspect it for any damage or replace the cable, but I was a little slow on that. So on second thought, take a bad situation and make it good. If the throttle hangs wide open, shift up and enjoy the ride.

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post #10 of 10 (permalink) Old 08-30-2010, 04:38 PM Thread Starter
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Thanks..and sorry about the info live in central new jersey, the bike is a 93 with under 12 k miles removed the carb bowl in the bike did not remove carbs and cleaned it , cleaned the jets, still will hold RPM for a time after the excell. is released, lubed as suggested same thing, the excell cable is free and moves as it should. Will look at the diaphram. thanks alot for the answers
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