Spark Plug Issues
Supporter
Joined: Jan 2007
Posts: 15,788
Likes: 5,621
From: along the shore of Mishigami
I recently watched a video on this topic. The person doing the video encourages the use of the HD plug but also suggested to gap at .038 inch because even though the .040 inch is a happy medium but he mentioned that after a few thousand miles, the gap has worked to .043 inch. I'm thinking of visiting this on my Harleys out in the garage after it warms up again. By the way the video was from DocHarley and Low Country HD. I believe he has some good information at times and isn't always selling a HD product. As far as fouling a plug, black fluffy is too much fuel (dirty Air Filter?) and a wet black plug is oil products, leaking valve guide seals. The 05's had this problem and required changing the valve guide seals.
Club Member
Joined: Feb 2013
Posts: 9,812
Likes: 8,712
From: Edmonton, Alberta
Here's a good rule of thumb:
If your bike ran well before you started working on and doesn't after you've "improved it", put it back the way it was. A Harley Davidson motorcycle is akin to a tractor in a field. No spark plug, oil, octane booster or anything else (except for a brief case of money) will make it perform better.
If your bike ran well before you started working on and doesn't after you've "improved it", put it back the way it was. A Harley Davidson motorcycle is akin to a tractor in a field. No spark plug, oil, octane booster or anything else (except for a brief case of money) will make it perform better.
This is bad news. I just bought E-3 spark plugs, Amsoil, NOS, and those little magnets you put in your gas tank.
I was banking on 150 hp/90 mpg.
Stellar HDF Member
Joined: Oct 2015
Posts: 2,681
Likes: 851
From: Puyallup, wa
Good luck with that unless you add a "Powered By Honda" sticker.
Stellar HDF Member
Joined: May 2015
Posts: 2,095
Likes: 304
From: mid Michigan
different EFI and ECM on bikes up to 2001. Earler bikes can run good with many different plugs. Delphi systems are best run with HD plugs, this has been discussed many times.
Grand HDF Member
Joined: Mar 2008
Posts: 4,997
Likes: 655
From: bklyn,ny
I used Denso IXU-22’s on my carbed ‘01 FXD. Started and idled better than stockers. I ever used them on my RK as I’m told you have to disable ion sensing.
Club Member
Joined: Aug 2018
Posts: 309
Likes: 541
From: Warner Robins GA
I run NGK iridium and have zero issues. I have run champion, harley to just see if there was a difference. At this point I don’t feel there is much if any differences between them exception is construction. Ymmv
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,143
Likes: 11,218
From: San Diego, CA
I am an OEM or Champion plug guy... They are cheap and I change them frequently...
The only thing I would suggest, is if you want to compare plugs (any type or manufacturer), make sure you are comparing two NEW plugs....
Too often people replace worn out plug type A, with a new plug type B, and think the better running characteristics are due to the type B plug..... Often, it's just the fact that a worn out plug was replaced with a new plug...
The only thing I would suggest, is if you want to compare plugs (any type or manufacturer), make sure you are comparing two NEW plugs....
Too often people replace worn out plug type A, with a new plug type B, and think the better running characteristics are due to the type B plug..... Often, it's just the fact that a worn out plug was replaced with a new plug...
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Road Warrior
Joined: Jul 2011
Posts: 1,936
Likes: 310
From: coastal sc
I would get an occasional misfire before changing the plugs, but no issues like I am having now. I'm guessing I should have left the gap on the NGK plugs alone and they would have worked out fine. I have 37,000 miles on my bike and I'm not due for changing out the fuel filter according to the service manual so I wouldn't think that would be an issue unless it just didn't last the length of its expected service life. The bike came with a 1450, but it has a tuner, upgraded pipes and air filter, and is now displaced at 1550. Not sure if that has any impact on what spark plugs I should be using?
My bike also sat for about 6 months or so while I worked on changing out the drive belt and clutch cable. This job resulted in all fluids (engine, trans, primary) being replaced so fouled oil can't be an issue. I have only ran about one tank of fuel since getting it back on the road and I have always ran premium fuel.
My bike also sat for about 6 months or so while I worked on changing out the drive belt and clutch cable. This job resulted in all fluids (engine, trans, primary) being replaced so fouled oil can't be an issue. I have only ran about one tank of fuel since getting it back on the road and I have always ran premium fuel.
Road Master
Joined: Nov 2009
Posts: 1,227
Likes: 417
From: Outer Banks, NC
Keeping in mind the gap slowly erodes wider as it ages, I would gap to the shortest dimension.