Adjusting Air Mix Screws Help - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 32 (permalink) Old 07-08-2013, 11:37 AM Thread Starter
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Adjusting Air Mix Screws Help

hi guys,


ive been reading allot about the air mix screws adjustment.
because i had allot of popping of the exhaust.
so went to check how far the screws were turned by the last owner.
they were pretty far i reckon about 3 1/2 turns OUT.
ive screwed them both out to just over the 2 1/2 mark.
but the bike whenever i opened the throttle it didnt want to rev down so i twisted the idle screw (the black knob) to bring it down to 1100 rpm (IDLE)
but it doesnt seem right after taking it for a 45 min spin.
the bike doesnt rev down fast enough as it normally should.
today even one time at the traffic light it stayed for about 10 seconds just under 3000 rpm.
so what am i doing wrong should i adjust the air mix screws out more or in ?
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post #2 of 32 (permalink) Old 07-08-2013, 11:56 AM
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Soooo... It didn't do this before adjusting the air mix screws?

Sounds to me more like a sticky throttle cable.


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post #3 of 32 (permalink) Old 07-08-2013, 12:12 PM Thread Starter
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im open to anything so how would i deal with a Possible sticky throttle cable?
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post #4 of 32 (permalink) Old 07-08-2013, 12:14 PM
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It may be a sticky throttle cable, or one of the carbs is loose causing an air leak (and thus a slow-to-idle siatuation).

Well if its a sticky throttle see if cable routing is an issue. If it isn't try lubing the cable. Worst case, replacement if it is damaged.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #5 of 32 (permalink) Old 07-08-2013, 12:19 PM
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Another way to try checking cable is to pay particular attention to the feel of the throttle itself. When you ease off on the twistie, does it return easily by itself or can you make the idle lessen by helping the twistie back to the low throttle position? I noticed this trait after rebuilding my carbs, I had somehow pinched my cables when refastening them to the throttle body. I adjusted the mounting bolts some, but still had a slight delay in the twistie response. I've just dealt with it by the way I twist the twistie.


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post #6 of 32 (permalink) Old 07-08-2013, 12:33 PM Thread Starter
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but this cant have happened by the idle screw right?
and the air mix screws?
because it doesnt feel like the throttle is sticking at all.
it goes back to start position as it should but the revs go back a few seconds later.
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post #7 of 32 (permalink) Old 07-08-2013, 12:35 PM
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Quote:
Originally Posted by juliascox View Post
but this cant have happened by the idle screw right?
and the air mix screws?
because it doesnt feel like the throttle is sticking at all.
it goes back to start position as it should but the revs go back a few seconds later.
Nothing to do with the air mixture screws.

My bet is you may have a loose carb/carb boot if your cables are closing properly @ the carb side of things.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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post #8 of 32 (permalink) Old 07-08-2013, 01:01 PM
..have a vulcan good day!
 
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Quote:
Originally Posted by thtanner View Post
Nothing to do with the air mixture screws.

My bet is you may have a loose carb/carb boot if your cables are closing properly @ the carb side of things.
x2 I too experienced slow rev drop back to idle, sometimes as long as 10 + seconds....discovered Air box to carb boots leaking....another symptom I had was 3K rpm difference <> Hot & Cold idle.
Seal your carb boots !


'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
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Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!
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post #9 of 32 (permalink) Old 07-08-2013, 01:47 PM
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Julia, if in your shoes, I would verify throttle cable adjustment. When adjusted properly, the return cable has a positive means of closing the throttle. The manuals list the adjustment procedure.

The idle mixture screws are only a backward patch when dealing with deceleration popping. On the VN, the cutoff valves operation should be able to verify by touch. They are both facing out.

Verify proper 'choke' operation visually.

If the cables are adjusted properly, high remaining idle will be caused by air (carb boots, vacuum leak, etc), or excessively lean.
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post #10 of 32 (permalink) Old 07-10-2013, 01:50 PM Thread Starter
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allright ive done some throttle cable adjustments and now it snaps back.
ive readjusted the airmix screws to 2 1/2.
bike had huge problem starting could this be due to me using the throttle evry time to see if it snapped back?
my exhaust fired loud pop.
but finally started let it run warm and in idle its fine but when i crank the throttle it takes forever to come down.
here is a youtube link.
the video is me trying a hot start en cranking the throttle.

http://youtu.be/q6TvsIDcEV0

by the way found out i have the yuasa yb14l-a2.
could this be a bad battery ?
let me know
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