Shocking driving and high irregular idles - Page 3 - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #21 of 47 (permalink) Old 07-02-2019, 01:43 PM
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Originally Posted by Panarock View Post
With vacuum line from the left carb do u mean the small tube in the Pic? No that's dry.

Sorry I tested the vacuum line coming from here (second Pic)
Can't tell on the 1st pic. 2nd pic, no.

It's the center port of the petcock, line runs to the side of the left carburetor.

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post #22 of 47 (permalink) Old 07-02-2019, 02:27 PM Thread Starter
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Quote:
Originally Posted by Panarock View Post
With vacuum line from the left carb do u mean the small tube in the Pic? No that's dry.

Sorry I tested the vacuum line coming from here (second Pic)
Can't tell on the 1st pic. 2nd pic, no.

It's the center port of the petcock, line runs to the side of the left carburetor.
Yes that one is completely dry
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post #23 of 47 (permalink) Old 07-02-2019, 03:22 PM
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Try the spray bottle from post #7.

If it won't idle without throttle, crank the idle setting way up. Then spray it.

At this point I'm not sure if the high rev is caused by an air leak, or you're giving it throttle to make it idle, in turn hitting the main jet on the carb with the clogged pilot.

Classic clogged pilot goes like this - Won't idle, unless you crank the idle up. Low power on takeoff (one cyl. running), then it explodes with power as soon as the main jet kicks in, around 2500-3200 rpm.

Even with the idle cranked up, it will still explode with power when the main kicks in.

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__________________________________________________ ____________
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post #24 of 47 (permalink) Old 07-02-2019, 05:23 PM Thread Starter
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I wasn't giving throttle in the video to keep the idle going, if the video was a bit longer you would see it idling smoothly at 1k rpm, only after longer rides 20min+ whenever I stop at a stoplight what you see in the video also happens on low idle. But as soon as it cools down a bit (like in the video where it sat for 10min) it only does it at high revs. With a cooled engine it doesn't give a problem at all

I will try the sprayed bottle tomorrow, it's getting late here. What exactly should I look for?, a change in sound? And white smoke from the exhaust as water vapor? Also do I spray water on a boot as if the bike was fully assembled?

Edit: the video should be up again. Not sure if u have seen it already. I deleted it once and reuploaded it for better quality.

Last edited by Panarock; 07-02-2019 at 05:36 PM.
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post #25 of 47 (permalink) Old 07-02-2019, 05:37 PM
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Not sure what's going on in the video. Ignition, ..maybe? Ignition parts do sometimes break down with heat, but still work when cold.

Could still be an air leak.

With the water spray, look for the idle to stumble, and steam out the back if you keep spraying. Do it with everything in place, spray around the clamps and boots on the engine side of the carbs.

2003-21k mi
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__________________________________________________ ____________
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post #26 of 47 (permalink) Old 07-07-2019, 08:49 AM Thread Starter
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Not sure what's going on in the video. Ignition, ..maybe? Ignition parts do sometimes break down with heat, but still work when cold.

Could still be an air leak.

With the water spray, look for the idle to stumble, and steam out the back if you keep spraying. Do it with everything in place, spray around the clamps and boots on the engine side of the carbs.

I have tried this and there was no difference. Any other ideas about what it could be? Could it be a dirty carb?

And iff it is electrical how would I be able to test this?
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post #27 of 47 (permalink) Old 07-07-2019, 08:51 AM Thread Starter
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Would letting someone adjust my carbs fix this? I replaced my airbox once which had a L turn for the air intake it also sputtered at high rpms. But once I switched back to my normal one it was fixed
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post #28 of 47 (permalink) Old 07-07-2019, 09:04 AM
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Would letting someone adjust my carbs fix this? I replaced my airbox once which had a L turn for the air intake it also sputtered at high rpms. But once I switched back to my normal one it was fixed
The only adjustment I can think of that might help ... Carb synch. But I think it would also have to be a sticking slide along with one butterfly being open too far.

You can visually check the butterflies to see if they are set the same, and opening at the same time. Then also a lift test on the slides to check their action. Might need to be fully warmed up to see if one slide is sticking.

In the video... Does the rpm increase by itself? Or do you raise the rpm to the point where it begins surging?

2003-21k mi
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__________________________________________________ ____________
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Owner's Manual: http://www.mediafire.com/file/nscb5f...ers+Manual.pdf
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post #29 of 47 (permalink) Old 07-07-2019, 11:25 AM Thread Starter
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Quote:
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Quote:
Originally Posted by Panarock View Post
Would letting someone adjust my carbs fix this? I replaced my airbox once which had a L turn for the air intake it also sputtered at high rpms. But once I switched back to my normal one it was fixed
The only adjustment I can think of that might help ... Carb synch. But I think it would also have to be a sticking slide along with one butterfly being open too far.

You can visually check the butterflies to see if they are set the same, and opening at the same time. Then also a lift test on the slides to check their action. Might need to be fully warmed up to see if one slide is sticking.

In the video... Does the rpm increase by itself? Or do you raise the rpm to the point where it begins surging?


I raise it myself by throttling. Also can u explain what the butterfly etc is? Im not familiar with the terms.

Also in the video that was max throttle.
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post #30 of 47 (permalink) Old 07-07-2019, 11:40 AM
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I raise it myself by throttling. Also can u explain what the butterfly etc is? Im not familiar with the terms.

Also in the video that was max throttle.
In that case, it may be a bad diaphragm. That's the round rubber part under the round cover on top of the carb.

The butterfly is the flap that rotates open when you twist the throttle. The butterflies on both carbs should begin to open at the same time. It's the plate with two screws seen in the center of the carb below.

I would look at the diaphragms first.



Carb Diaphragm Part #1 below


2003-21k mi
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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

Last edited by Spockster; 07-07-2019 at 11:42 AM.
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