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Discussion Starter · #1 ·
Hi Im having a problem with the rear plug fouling up after a month or so.
Its sooty not oily. I change the plug and the problem is gone.
Ive been using NGK,s and have never had a problem in my 93 Heritage before. Any ideas as to a hotter rated plug that may solve the problem?
cheers Popeye
 

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Popeye said:
Hi Im having a problem with the rear plug fouling up after a month or so.
Its sooty not oily. I change the plug and the problem is gone.
Ive been using NGK,s and have never had a problem in my 93 Heritage before. Any ideas as to a hotter rated plug that may solve the problem?
cheers Popeye
Hotter plugs do not burn hotter, they just dissipate heat more slowly. Too hot a plug will cause other problems. Your bike will run best with the factory recommended plugs... don't waste money on those fancy splitfires, either. They are a joke, and an expensive one at that! Besides, changing to a "hotter" plug is just covering up the real problem.

First, did you change your plug wires? If not, do it first. Maybe you could swap out the coil, too. It could be getting weak. Try the other steps first if you don't happen to have a spare coil lying around.

Second, how often do you use the choke? Try not to use it at all unless it's really cold out. Overuse will foul plugs quickly. I rarely use mine.

And third, It sounds to me like you may have an intake leak. If it's leaking and you try to tune the bike, one cylinder will get a good mixture and the other will be too lean or too rich. I'd say that your front cylinder is leaking and running lean. Then, when you tune it to get the front cylinder running right, the rear will be too rich. This is what usually what happens with those kind of leaks.

Spray some WD40 (using the red plastic nozzle that comes with it) around the intake manifold while the bike is idling. Don't worry about getting it on the shiny parts... IF you're one of "those people", it'll wash off easily. :D
If you notice that the engine slows down, even slightly, then you have a leak. Remove the carb, intake, replace seals (all of them), reinstall manifold, THEN install the carb. It's hard to properly align the intake with the carb mounted to it since you need to look inside the intake to see if it's lined up with the heads' ports. It wouldn't hurt to throw a rebuild kit in the carb while you've got it off. They are cheap and it'll be good insurance against problems in the near future.

After all of this is checked, put it on a dyno to get it tuned correctly. Then you should be good to go for a long time.
Good luck! :thumbsup:
 

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Discussion Starter · #3 ·
Thanks for the info I,ll follow your recomendations and let you know the results. p.s. Im not too worried about the shiny bits haha.
thanks again
popeye
 

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i have sprayed W.D.40 around a leaking joint and the engine sped up. W.D. 40 combusts, so if there is a leak and you are running lean, it will run better for as long as you spray
 

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bonnie john said:
i have sprayed W.D.40 around a leaking joint and the engine sped up. W.D. 40 combusts, so if there is a leak and you are running lean, it will run better for as long as you spray
Maybe a very small leak will cause the engine to speed up by only letting a small amount through. This is due to the propellant getting sucked into the leak and igniting. But, if you spray the liquid heavily into a normal leak, keeping the nozzle a few inches from the leak, it will slow the engine.

Yes, WD40 combusts, but not very easily and can stall your engine if too much gets in. I know... it happens to me all the time. :) The WD40 spray is more of the consistancy of thin oil (it's actually oil-based) and has a much higher flashpoint (131 deg F) than gasoline (-40 deg F). That's the flashpoint of the vapors, not the ignition point of the liquid, which is much higher for WD40. It's vapors aren't released as quickly as gasoline. Even their High Performance Penetrant Spray (107 deg F) and their silicone spray lubricant (-20 deg F) burn more easily.

I've seen people use brake cleaner because the WD40 didn't show much difference. I'm sure you know that using brake cleaner is NOT A GOOD IDEA! It will explode! :beer:
 

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spark plugs

Has this happened just this once or all the time? If it clears up after the new plug, it may be that the spark plug was faulty. I have had this happen before. I have tried many different brands of plugs but I seem to keep coming back to HD plugs. They seem to work better for me. If it continues to happen it probably is an intake leak alright.
 

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Discussion Starter · #7 ·
Plugs

It only happened the once last riding season but it happened about once a month or so the year before?.
 

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Plugs

Also, don't run those h-d plugs, try using an autolite equivelent. I've run these for years and get at least 30,000 miles on a pair! NO ****! They will also cost about 1/3.
 

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Shovel Head Ted said:
Has this happened just this once or all the time? If it clears up after the new plug, it may be that the spark plug was faulty. I have had this happen before. I have tried many different brands of plugs but I seem to keep coming back to HD plugs. They seem to work better for me. If it continues to happen it probably is an intake leak alright.
I agree. Autolites are ok, but I've never had trouble with the Harley plugs, which I believe are made by Champion at the moment. I used Autolites for a couple years when I was able to get them with a 1 year warranty.... each spring I would return the old ones and get a new set, for FREE!! :)
 

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...and that's probably why they quit offering the warranty
 

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cainpole said:
...and that's probably why they quit offering the warranty
Actually, after posting that message, I called Advance Auto and they are still offering the warranty, at least at this store. I've been using Harley plugs for the past couple years with no troubles, so I think I'll just stick to them. They're cheap enough. If it ain't broke, don't fix it. :)
 
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