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Author Topic: Engine shutting off/Mis-fire on start up (eliminated) 38,500+  (Read 2576 times)

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Jack

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    • CVO1: 07 FXSTSSE Amarillo Gold/Candy Tangerine (1/540) thanks Dude
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 :beatdeadhorse: 2007 Service Man/Handbook says spark gap variable of .038-043.
as you can see below I use NGK Iridium IX (DCPR8EIX) pt #6546.  NGK recommends the #7 hotter
plug which in some informational areas means 70-100 deg's hotter spark. Somehow I tend to think
this will bring on a hotter engine as well. By all accounts my plugs read exactly as they should, slightly
dusty with a light gray, little more gray on back plug.  Chris Wadell Cycle Solutions
http://www.cyclesolutionsonline.com/ put the  Jet Scream unit over the throttle body back in 2008
Thunder in The Valley, Johnstown, PA. and recommended that plug with the conversion.  It has always
burned true to the charts.  And had since installed the SE 10 mm plug wires.

My engine until recently since the Gap was reduced from .040 to .038 was when warm/hot backfire
1/3 of the time at start up, and progressed to cold start up.

I was headed to Pittsburg & for the real test of the fine tune yesterday.  The Bike never shut down,
and this was in bumper to bumper 3 mile traffic near Squirrel Hill coming and leaving the area.  The
ambient temp was @ 80 deg. There was not the uncomfortable heat coming off the engine when in
stalled traffic either, but then again I was all leathered up.  I have not had a bad start in over a dozen
starts since the adjustment.

I believe the Coil has been overworked which is causing the problem of shut down. A closer look
after more miles may allow another adjustment to .039

I somehow feel the Bike is running a slightly higher RPM in normal operation now due to the Gap.
More like a shorter stroke connecting rod.


http://www.custom-car.us/ignition/spark-plug/gap.aspx

As a rule, a properly gapped spark plug will burn hot without being too wide at high rpm to cause a misfire. Ironically, the car manufacturer's recommended spark plug gap is not optimal! The recommended spark plug gap is designed to be adequate for cold starting and smooth driving on a car that is in need of an engine tune up. If you drive your car normally and tune the engine regularly, you can increase the spark plug gap by about 0.010" for better performance and better fuel economy. However, if you drive at full throttle most of the time, you should reduce the gap by about 0.010" for better performance. The spark plug itself, and the residue that forms on it, would indicate whether the gap is too big or too small. A light brownish discoloration of the tip of to porcelain insulator indicates the proper operation of the spark plugs with the gap being ideal or close to ideal for the most recent engine speeds. Thus, to check the spark plug gap at high engine speeds, you'd need to run at full throttle and immediately turn the ignition off without allowing the engine to idle. But ultimately, you'd need to run your car on a dynamometer to find the best spark plug gap, and the right ignition timing for your engine.

Remember that when you increase the spark plug gap you need more voltage from the ignition coil to create a spark across the spark plug gap. We'll discuss ignition voltage at a later stage. When a greater voltage is required to create a spark, cold starting and firing fouled spark plugs become more difficult. Therefore you should ensure that your secondary, high-tension ignition wiring is at least 8 mm in diameter, and that it is always clean, dry and in peak condition. Also note that it is not advised to adjust the gap on a multi-electrode spark plug as this will affect the proper operation of the spark plug.



« Last Edit: July 27, 2012, 05:34:55 PM by Jack »
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FXSTSSE
H-D Tribal Mirrors (92410-09)
H-D medium low detachable (round stock) sissy bar
2006 Bobtail fender rack & trans dip stk w/medallion
Jet Scream (air delivery)
10mm SE plug wires
NGK Iridium IX (DCPR9EIX) 2316
Mercury Marine QUICKSILVER 20-W50
MOTORKOTE (petroleum hydrocarbon) in all 3 areas
RED LINE HEAVY SHOCKPROOF
93 Octane
Lyndall "Z" Racing Brake Pads "Gold"
(7059-G) ft
(7196-G) rr
H-D Crash Bar

Jack

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    • CVO1: 07 FXSTSSE Amarillo Gold/Candy Tangerine (1/540) thanks Dude
    • CVO2: 98 Lincoln LSC Ivory Pearlescent (34K)
    • CVO3: 87 Porsche 944 Rose Quartz
Re: Engine shutting off/Mis-fire on start up (eliminated) 38,500+
« Reply #1 on: July 27, 2012, 05:52:06 PM »

 :beatdeadhorse: Follow UP.

Friday, ambient temp. 90 first warm start up failure. After several miles engine started into the slow 
idle leading into a shut off, but held coming to a rolling stop.

I have experienced in the past that the ECM needs to learn new parameters, usually @ 500 miles.

One note:  I included the entries above on spark plugs from the 'Tuner Car' site only for reference,
as I would think an aircooled bike would be affected much more severely in differences referred to.

As usual, use your own discretion on where you may go with any of this information.......J
« Last Edit: July 27, 2012, 06:20:49 PM by Jack »
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FXSTSSE
H-D Tribal Mirrors (92410-09)
H-D medium low detachable (round stock) sissy bar
2006 Bobtail fender rack & trans dip stk w/medallion
Jet Scream (air delivery)
10mm SE plug wires
NGK Iridium IX (DCPR9EIX) 2316
Mercury Marine QUICKSILVER 20-W50
MOTORKOTE (petroleum hydrocarbon) in all 3 areas
RED LINE HEAVY SHOCKPROOF
93 Octane
Lyndall "Z" Racing Brake Pads "Gold"
(7059-G) ft
(7196-G) rr
H-D Crash Bar

dlaws01

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Re: Engine shutting off/Mis-fire on start up (eliminated) 38,500+
« Reply #2 on: July 27, 2012, 08:33:24 PM »

Just an idea but why don't you install a set of stock H-D plugs back in to see if the spark plugs are the problem?  Cheap enough to try this "air force" check. I've learned over the years to troubleshoot problems starting from the most simple first progressing to the most complex last. Good luck
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AXIL

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Re: Engine shutting off/Mis-fire on start up (eliminated) 38,500+
« Reply #3 on: July 27, 2012, 09:00:18 PM »

    It's not the spark plug..... Take the bike to somebody who knows what the f... there are doing.
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grc

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Re: Engine shutting off/Mis-fire on start up (eliminated) 38,500+
« Reply #4 on: July 27, 2012, 09:33:30 PM »

    It's not the spark plug..... Take the bike to somebody who knows what the f... there are doing.

 :2vrolijk_21:   Thank you for saying what I was thinking. 


Jerry
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H-D and me  -  a classic love / hate relationship.  Current score:  love 40, hate 50, bewildered 10.
 

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