Spark plug gap smaller than spec

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Jun 5, 2013 | 02:19 AM

#11

my67pnycar

Elite HDF Member

Joined: Oct 2010

Posts: 3,504

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From: DOWN SOUTH

Thats what its all about T-Dog, bonding with your ride and saving the $$$ for upgrades/fun instead of giving it to the dealer to maintain your bike.

Jun 5, 2013 | 03:37 AM

#12

T_Dogg80

Thread Starter

Road Captain

Joined: Sep 2012

Posts: 662

Likes: 1

From: Kelowna, BC, Canada

Quote:

Originally Posted by my67pnycar6

Thats what its all about T-Dog, bonding with your ride and saving the $$$ for upgrades/fun instead of giving it to the dealer to maintain your bike.

You got that right! Wrenching on the bike is almost as satisfying as riding it. Almost.

Jun 5, 2013 | 03:50 AM

#13

Jackie Paper

Seasoned HDF Member

Joined: Mar 2010

Posts: 38,537

Likes: 6,412

From: Honah Lee

Is it snowing up there, already?

Actually your mechanic was pretty smart. It increased the advance by about .010 . Probably not a lot as fast as electricity travels at, but more.?

Could pre ignition hammered the gap closer?

Last edited by Jackie Paper; Jun 5, 2013 at 04:00 AM.

Jun 5, 2013 | 08:09 AM

#14

btsom

Grand HDF Member

Joined: Jan 2012

Posts: 4,458

Likes: 2,877

From: Oklahoma

Quote:

Originally Posted by mikelikesbikes

Interesting as any HD plugs I bought were already gapped right close to .40. I'd say if it is running okay leave it be. Conversely an Indy told me to try .25. DO NOT do that!!!!! Ran like crap. I would be curious to know how the gap works out in the long run.

Could you be a bit more descriptive of the actual symptoms? That is a little vague, though I do understand you weren't happy. Loss of power, rough idle, difficult starts, pinging, loss of fuel economy, ran hotter/colder than normal, changed the sound of the exhaust, hesitation when adding throttle etc.

Jun 5, 2013 | 08:22 AM

#15

Blue U

Novice

Joined: May 2013

Posts: 17

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From: Michigan

A lot of older engines were always gaped at 25, the leaner the fuel mixture the bigger the gap, if fuel mixture is set richer it could run good at that gap.

Jun 5, 2013 | 09:51 AM

#16

gmc

Road Warrior

Joined: May 2008

Posts: 1,802

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From: Salt Lake City, UT. Dushore, Pa.

Trying to post an article I have fr. Hot Bike. I haven't found where they have hotter coils for the new bikes since I think with the ECM they have had to upgrade them. I did change my plug wires to the Thundervolt wires for better spark but have had to keep gap .040 since the ECM doesn't like it much wider.

Attached Thumbnails

Spark plug gap smaller than spec-sparkpluggapjpg.jpg

Spark plug gap smaller than spec-sparkplugwires.jpg

Last edited by gmc; Jun 5, 2013 at 10:27 AM.

Jun 5, 2013 | 09:58 AM

#17

lionsm13

Seasoned HDF Member

Joined: Oct 2007

Posts: 56,052

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From: Western South Dakota

Quote:

Originally Posted by T_Dogg80

Bored tonight
since the bike runs perfectly and both plugs looked good, should I re gap them or leave them alone?
.

Ahhhhh think you answered your own question?

Was it necessary to even ask?

Fix it if it ain't broke then, eh?

Jun 6, 2013 | 09:53 AM

#18

mikelikesbikes

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Joined: Mar 2012

Posts: 11,232

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From: Socialist Republic of the USA

Quote:

Originally Posted by btsom

Long story and I hate to type but this was just after having Andrews 37 cams installed along with some other work. Like said, Indy suggested .25 so I tried it. Most noticeable problem was missing, spitting and sputtering. My Road King is an 01 non EFI so your results may vary. I rode it less than a hundred miles before I put new plugs in gapped at .40 and bike now runs much better. Still an issue with the carb I believe as it will occasionally spit and gas mileage is not what it used to be but can't seem to nail it down yet. Have some oil seepage (very slight) at one of the breather bolts so gonna check into that.