Engine will only run with choke on - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 13 (permalink) Old 08-07-2011, 02:25 PM Thread Starter
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Engine will only run with choke on

I just bought an 02 Vulcan and it wasn't running at the time. I got the carbs off (pretty terrible design there) and cleaned them thoroughly. It has aftermarket pipes on it, Jambino or something like that. The mains in the carb are 138 and the pilots are 38s. The mains seem a bit oversized but that shouldn't affect the idling of the bike. I have to keep the choke on pretty much full to get it to idle. If I keep the throttle turned I can get it to run without choke above 2500 rpm. I know the pilots and mains are very clean, I spent about 20 min. on each one. Should I try some seafoam before I pull the carbs again or is there something I am missing. I tried adjusting the pilot screws but it didn't seem to make much of a difference.
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post #2 of 13 (permalink) Old 08-07-2011, 03:28 PM
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Quote:
Originally Posted by Cricketo99 View Post
It has aftermarket pipes on it, Jambino or something like that.
Perhaps you mean Jardine??

As for the idle, have you tried turning the idle adjustment -- the black, knurled knob on the left side?

I confess I'm not much of a mechanic, so maybe I'm being too simplistic. I'm sure others will get you on the right track.

John

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post #3 of 13 (permalink) Old 08-07-2011, 03:37 PM
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Johnm is right, turn the idle knob (black knob on left side of motor) and adjust idle to 1100. If bike still doesn't run by itself you are probably not getting enough fuel. See if fuel lines are clogged and make sure the hose that goes into the right ear (air cleaner) is plugged in.

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post #4 of 13 (permalink) Old 08-07-2011, 03:57 PM Thread Starter
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Well currently I have it running with just the carbs open, as in not hooked up to the surge tank. I felt like I would probably have to pull something else back off and I didn't want to have to pull everything off again. Would that make that much of a difference? On a good running bike what should the idle be with the choke on, mine runs low, probably about 1000-1200 rpm.
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post #5 of 13 (permalink) Old 08-07-2011, 04:22 PM
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Idle with full choke could be as high as 1800. So the advice seems correct to adjust your idle with the idle knob on the left side to 1100 with the choke off and everything should fall into place.

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post #6 of 13 (permalink) Old 08-07-2011, 04:23 PM Thread Starter
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I sure hope so, currently I am trying to locate a fan so I can run it again, so it might be a while
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post #7 of 13 (permalink) Old 08-07-2011, 05:13 PM
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If the black knob doesn't help look at your pilot jets again. Your getting enough fuel because you can run it up over 2500 with no choke, and this is past the range of the pilot jets. Mine were both clogged rock solid. Not the side holes but the extremely small hole in the shaft that is about the diameter of a wire brush bristle. I replaced my jets because I ditched my stock airbox. Oh and I only knew they were clogged by trying to blow air through them. Not suggesting you do that but I'm kinda old school, if that's what you'd call it. Whatever, it worked for me. Good luck.
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post #8 of 13 (permalink) Old 08-09-2011, 12:38 PM Thread Starter
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Okay I can now idle with the choke off, I had to fine tune the pilot screw and also turn the idle knob out a bit. Now I think that the main jet is way oversized. Like I said it has a 138 in which seems a bit large considering stock is 132. From idle if I slowly turn the throttle it will bog real bad and sometimes stall. If I goose the throttle I get a nice plume of black smoke out the tailpipe which leads me to believe I need to step down the mains. What should I step down to, stock 132 or maybe a 134 or something like that?
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post #9 of 13 (permalink) Old 08-10-2011, 02:26 AM
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Quote:
Originally Posted by Cricketo99 View Post
I sure hope so, currently I am trying to locate a fan so I can run it again, so it might be a while
If you just need a fan blade, and not the fan motor too, you may want to get an aluminum blade from Muzzy:
http://www.muzzys.com/fans.html

Hmmm, my Vipre security won`t let me access that site since upgrading last month, and I don`t know how to change the settings.
One more thing to learn I guess.

Gordon

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Purchased May 16, 2008
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post #10 of 13 (permalink) Old 08-10-2011, 09:05 AM
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Quote:
Originally Posted by Cricketo99 View Post
Okay I can now idle with the choke off, I had to fine tune the pilot screw and also turn the idle knob out a bit. Now I think that the main jet is way oversized. Like I said it has a 138 in which seems a bit large considering stock is 132. From idle if I slowly turn the throttle it will bog real bad and sometimes stall. If I goose the throttle I get a nice plume of black smoke out the tailpipe which leads me to believe I need to step down the mains. What should I step down to, stock 132 or maybe a 134 or something like that?
The aftermarket exhaust manufacturers " suggest" going up 1 size larger on the main jet, which would be 134.

JM2001

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