engine miss? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 11 (permalink) Old 02-08-2012, 08:12 PM Thread Starter
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engine miss?

I noticed something really weird the other day. When riding my Vulcan, it runs perfectly, no missing or loss of power. However, If i rev to about 4,000 in neutral and hold it, it starts to miss and wander up and down in rpms, but it NEVER misses when riding, or under load. anything i can do? or just not worry about it. It also idles at 1,100 so smoothly. I ran some Lucas gas treatment through my system, only ridden about 50 miles on that tank so maybe that will fix it.

1986 Vn750
18,800 miles, and counting
Bone Stock
New cam chain tentioners
all fluids changed
Spline Lube
windshield
Engine Guard
B-stone S11 RWL-stock sizes
*wanted*
New grips

2001 Vn750
13,100 miles, and counting
spline lube
Bridgestone S11 100/90
Shinko 170/80
rear end oil change
aftermarket mirrors
windshield
otherwise all stock
*anticipated mods*
Engine Guard
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post #2 of 11 (permalink) Old 02-09-2012, 12:09 AM
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Did you check if your battery terminals are tight? The jumping tach is a good sign of a loose ground and that's about the easiest place to start looking.

"Show me a man who makes no mistakes, and I'll show you a man who doesn't do things." Theodore Roosevelt."

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Current projects - 1986 VN750 & 1988 EL250
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post #3 of 11 (permalink) Old 02-09-2012, 01:36 PM Thread Starter
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Battery cables are tight. When im riding that tach is super smooth and steady.

1986 Vn750
18,800 miles, and counting
Bone Stock
New cam chain tentioners
all fluids changed
Spline Lube
windshield
Engine Guard
B-stone S11 RWL-stock sizes
*wanted*
New grips

2001 Vn750
13,100 miles, and counting
spline lube
Bridgestone S11 100/90
Shinko 170/80
rear end oil change
aftermarket mirrors
windshield
otherwise all stock
*anticipated mods*
Engine Guard
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post #4 of 11 (permalink) Old 02-09-2012, 11:05 PM
..have a vulcan good day!
 
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cylinder kicking out

I had a similar problem.... but more evident at idle. I pulled spark plug wires to determine rear cylinder intermittent spark. Cleaned all electrical connections, new spark plug wires...no help. Replaced CDI ignitor box.. Problems gone.
Good Luck
WilliamTech

'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
Additional Flashing LED Brake Light on Trunk
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 #5 of 11 (permalink) Old 02-09-2012, 11:10 PM Thread Starter
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I do want to put 4 new plugs in this spring. It has Denso's in their now. I think i want NGK Iridiums.

1986 Vn750
18,800 miles, and counting
Bone Stock
New cam chain tentioners
all fluids changed
Spline Lube
windshield
Engine Guard
B-stone S11 RWL-stock sizes
*wanted*
New grips

2001 Vn750
13,100 miles, and counting
spline lube
Bridgestone S11 100/90
Shinko 170/80
rear end oil change
aftermarket mirrors
windshield
otherwise all stock
*anticipated mods*
Engine Guard
1986vn750 is offline  
post #6 of 11 (permalink) Old 02-10-2012, 08:30 AM
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i put iridium's in mine and it starts and runs a whole lot better - but when i first crank mine - before it is fully warmed up - it will miss a bit until i have ridden a few miles then all is good. (the iridiums fixed everything but that) I haven't figured mine out yet - are you trying it when it's cold?

That can't be my bike - it aint movin'
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post #7 of 11 (permalink) Old 02-10-2012, 08:44 AM
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Quote:
Originally Posted by trekbiker View Post
i put iridium's in mine and it starts and runs a whole lot better - but when i first crank mine - before it is fully warmed up - it will miss a bit until i have ridden a few miles then all is good. (the iridiums fixed everything but that) I haven't figured mine out yet - are you trying it when it's cold?
That's typical of any engine with carbs and a choke ( a gas enricher on our bikes). The only way to eliminate the condition would be to install fuel injection. The engine should smooth out in a couple of minutes of idling at 1/2 choke.

JM2001

" Loud Pipes Risk Rights "

2001 Vulcan 750
marbled
TOC upgrade on ACCT
Air/fuel mixture set to 2 1/2 out
rectifier relocated
splines lubed
iridiums
decals removed
upgraded mirrors
Pic up coil mod done
degoated
All LED lighting
Upgraded Mosfet rectifier
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post #8 of 11 (permalink) Old 02-11-2012, 12:08 AM Thread Starter
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It did it when it was hot, riden after about 20 miles. But I guess it really doesnt bother me because It runs strong and smooth under power.

1986 Vn750
18,800 miles, and counting
Bone Stock
New cam chain tentioners
all fluids changed
Spline Lube
windshield
Engine Guard
B-stone S11 RWL-stock sizes
*wanted*
New grips

2001 Vn750
13,100 miles, and counting
spline lube
Bridgestone S11 100/90
Shinko 170/80
rear end oil change
aftermarket mirrors
windshield
otherwise all stock
*anticipated mods*
Engine Guard
1986vn750 is offline  
post #9 of 11 (permalink) Old 02-11-2012, 07:53 AM
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Quote:
Originally Posted by 1986vn750 View Post
It did it when it was hot, riden after about 20 miles. But I guess it really doesnt bother me because It runs strong and smooth under power.
It could be that you have a dirty pilot jet. The pilots supply the fuel to the carbs up to 2500-3000 rpms ( IIRC). The engine may smooth out when the main jets kick in. I would try about 6 ounces of SeaFoam in a full tank of gas.

JM2001

" Loud Pipes Risk Rights "

2001 Vulcan 750
marbled
TOC upgrade on ACCT
Air/fuel mixture set to 2 1/2 out
rectifier relocated
splines lubed
iridiums
decals removed
upgraded mirrors
Pic up coil mod done
degoated
All LED lighting
Upgraded Mosfet rectifier
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post #10 of 11 (permalink) Old 02-11-2012, 11:12 AM Thread Starter
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Yeah, I was out of seafoam so I have some Lucas fuel treatment in there now, I've run about 50 miles on that tank. I will try some seafoam if this doesnt help.

1986 Vn750
18,800 miles, and counting
Bone Stock
New cam chain tentioners
all fluids changed
Spline Lube
windshield
Engine Guard
B-stone S11 RWL-stock sizes
*wanted*
New grips

2001 Vn750
13,100 miles, and counting
spline lube
Bridgestone S11 100/90
Shinko 170/80
rear end oil change
aftermarket mirrors
windshield
otherwise all stock
*anticipated mods*
Engine Guard
1986vn750 is offline  
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