Desperate - Unable to solve. - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 18 (permalink) Old 07-14-2015, 12:24 PM Thread Starter
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Desperate - Unable to solve.

Been wrestling with this issue for over a year now.

Bike is stuttering and stalling on me after it gets warm. It idles fine. as long as rpms are up a bit it seems ok. as soon as i let off the throttle it rpms down and stalls. From a start it stutters a bit at low rpms then jumps alive once i get beyond 1/4 - 1/3 throttle or so.

Bike is ear shaved, rejetted (problem existed prior to this and yes carb vent is going to tank underside dead air location), mcct's, new plugs, new plug caps, new wires, new rear ignition coil, new free flow petcock, tank thoroughly cleaned, carbs thoroughly cleaned and partially rebuilt by me (worn parts only...no change), then rebuilt professionally, He also redid the throttle cables, carb boots (old ones were not sealing properly) and new r/r (bike wasn't charging).

The mechanic said that the rear cyl was not firing properly and suggested i replace the ig coil.

My wife is giving absolute hell and i'm losing my mind. I love the bike and want to work through the problems but her mouth is getting to me and it's making me want to throw the both of them out the window.

HELP!!

mike

2006 Vulcan 750
Ear Shaved
Re-jetted
ACCT --> MCCT Conversion
TW200 Petcock
www.michaelcmichaeldo.com
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post #2 of 18 (permalink) Old 07-14-2015, 02:27 PM
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How do the plugs look? are they wet when you pull them after it stalls? Wet plugs means too rich or flooding.

check your "choke" plunger on the carb to ensure it is fully IN when the choke lever is in the OFF position.
Also check for air leaks in the carb boots and plunger of the choke. spray some starter fluid around them at idle....if it sucks it in the RPM's should change.

I would also ensure your battery is charged and you are getting good output from the charging system even though you changed the R/R. it could still be a bad stator.

MCCT's could be too tight causing the timing chain to slow at idle and stall. re-adjust them so they are just tight enough to stop the chains from rattling, but no too tight or your RPM's will drop due to the tension.
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post #3 of 18 (permalink) Old 07-14-2015, 03:26 PM
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MAYBE YOU'RE GETTING OLD LIKE ME

In recent times I've forgotten internal carb bits or left them loose so they came adrift. Did it ever run right after the mod/rejet? Is it effecting one or both cylinders? It sounds like you infer replacing that coil eliminated any electrical glitch. A buddy of mine runs a shop and does 60%+ of his business in carbs. Rejetting and airbox removal are great for creating horrible problems. Whose(proven)jetting specs did you use? Spraying carb/brake cleaner on suspect areas of carbs while idling can show up air/vacuum leaks you've missed. Like so many others I learned(40 yrs ago)that the engineers did a great job getting the carbs working properly. In 50 yrs of wrenching on my 60+ bikes I've gone through all the mistakes anyone can make. My VN is stock except for foam filters(I forget if foam is stock)and Victory mufflers in place of the stock shorties and runs beautiful. On the other hand the FT500 Ascot I recently acquired was given the larger jetting recommended by the moderator/guru of the FT forum allbeit w stock airbox. It runs fine and pulls one tooth taller gearing w ease-60+mpg too. All that said there could still be electrical issues as mundane as a bad ground. Good luck. GJ
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post #4 of 18 (permalink) Old 07-14-2015, 05:43 PM
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guzzi john he stated it had the issues prior, and the earshave mod (aka pod filters) is quite common. 40/140 2 shims or 42/142 2 shims are common combos. I'm at 140/42, 2 shims myself.

Best bet is to check those rear plugs to see if they're wet (getting gas, but not igniting). Ignition coils are really cheap on eBay, may be worth a shot if everything else checks out.

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 18 (permalink) Old 07-14-2015, 06:13 PM
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The carb needles can not be interchanged. If the carb needles are on the wrong carb engine will run bad.

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post #6 of 18 (permalink) Old 07-15-2015, 01:27 AM Thread Starter
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The rear ig coil was just changed out w/ brand new one. The issue was present before all changes to the bike. It ran like a dream for a month or 2 then slowly the issue began. Started out as an intermittent stutter every now and then. It increased gradually until it was every ride all the time. Eventually it began stalling badly. None of the changes fixed the issue.

For the earshave I followed the sticky in the carbs section. The only thing i changed was omitting the 2nd emgo filter for the carb vent and ran that to the undertank location.

Since the spark plug cap change (what i did to it yesterday morning) the stalling is far less pronounced. It only stalled on me 4-5 times vs the usual 20 or so on a 2-3 mile trip...

I'm thinking i'm going to have to chase down a potential wiring/grounding issue. Not looking forward to it.

2006 Vulcan 750
Ear Shaved
Re-jetted
ACCT --> MCCT Conversion
TW200 Petcock
www.michaelcmichaeldo.com
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post #7 of 18 (permalink) Old 07-15-2015, 09:09 AM
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The one thing that you have not mentioned (or I can't find it) is if you have cleaned the ignition switch. You're like well how can that have anything to do with anything? Nothing works without it is the short answer, and the electrical in this bike is whacked so, take the puck under the key apart and carefully clean it. Get those contacts shiny. Stretch the little spring ever so slightly. Watch that you don't lose the spring and the ball bearing when you take it apart. Also there isn't much play in the cables and they can sometimes pop loose so careful or you'll have to solder them back on.

If you have trouble or break it putting it back together, use superglue and a zip tie. Just clean that sht.

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post #8 of 18 (permalink) Old 07-15-2015, 10:42 AM
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Quote:
Originally Posted by mcharles13 View Post
The rear ig coil was just changed out w/ brand new one. The issue was present before all changes to the bike. It ran like a dream for a month or 2 then slowly the issue began. Started out as an intermittent stutter every now and then. It increased gradually until it was every ride all the time. Eventually it began stalling badly. None of the changes fixed the issue.

For the earshave I followed the sticky in the carbs section. The only thing i changed was omitting the 2nd emgo filter for the carb vent and ran that to the undertank location.

Since the spark plug cap change (what i did to it yesterday morning) the stalling is far less pronounced. It only stalled on me 4-5 times vs the usual 20 or so on a 2-3 mile trip...

I'm thinking i'm going to have to chase down a potential wiring/grounding issue. Not looking forward to it.

I gave some suggestions, but not sure if you looked into any of them or not.

Check your GROUNDS....negative to the battery box, the engine ground cable as well as the one from the battery box to frame.
Check ALL grounds/connectors you can find including the ones going to the coil.
The ignition coil is working off a pulsed ground, so most likely you have a corroded connection someplace that has been slowly getting worse. Changing the coil may have helped a bit, but it could be several oxidizing connections that combined to produce the issue.
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post #9 of 18 (permalink) Old 07-15-2015, 06:30 PM
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Some times the kickstand can cause this very problem. Spray and work the safety switch at the stand this may help your problem.

02 honda sabre 1100
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post #10 of 18 (permalink) Old 07-15-2015, 09:02 PM
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SLOW DEATH??

Ah the further discussions light candles. I too think electrical gremlins. Ign.switch,rocker kill,clutch,side stand. All those little gizmos get poopy(dirty/corroded)over time. Like shaft splines they should get occasional peeks. I had a rocker kill give a somolar issue this past year.(just can'y remember which bike)Sorry to anyone offended by airbox defense,is there any data on this forum showing any dyno/efficiency/mpg changes resulting from the afore mentioned jettings?GJ
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