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Aux Spark Plugs

jammess

jammess

Jammess
Recently performed 12K service to 04RT and noticed that there was a marked difference in the color of the secondary plugs and primary plugs. The primary plugs looked perfectly normal in color while the secondary plugs looked black and somewhat oily. The bike seems to run well with no sign of pinging nor does it use oil. It did use oil up to about 9K miles but then abruptly stopped any discernable trace of oil consumption. Also, bike shows no tendency to surge at all and gets about 42 to 45 MPG. Still, I can't help wondering why the secondary plugs looked so much different from primaries. I wonder if anyone has any theories or maybe an explanation for this odd phenomenon. Excuse bad spelling.
 
Are they the same plugs??

Two possibilities, 1) the darker plug is a colder plug

and 2) the mixture is richer where the plug is located....

And I 'm sure there are other possibilities...
 
Red100RT said:
I wonder if anyone has any theories or maybe an explanation for this odd phenomenon.
Click to expand...
The secondaries may not be firing. Check the resistance of the spark plug caps.
 
spark plug caps

I don't understand what you are refering to when you say resistance of spark plug caps. Do you mean measure resistance from the cap to ground? If this is what you mean what kind of reading should I see?
 
Red100RT said:
Do you mean measure resistance from the cap to ground? If this is what you mean what kind of reading should I see?
Click to expand...
Yes. I'm guessing you should see about the same as the primary caps' resistances. Someone with a manual might post the numbers. For spark plug caps, it is generally a range.
 
Red100RT said:
Recently performed 12K service to 04RT and noticed that there was a marked difference in the color of the secondary plugs and primary plugs. The primary plugs looked perfectly normal in color while the secondary plugs looked black and somewhat oily. The bike seems to run well with no sign of pinging nor does it use oil. It did use oil up to about 9K miles but then abruptly stopped any discernable trace of oil consumption. Also, bike shows no tendency to surge at all and gets about 42 to 45 MPG. Still, I can't help wondering why the secondary plugs looked so much different from primaries. I wonder if anyone has any theories or maybe an explanation for this odd phenomenon. Excuse bad spelling.
Click to expand...

Mine looked the same way.
The secondary plug is/was one heat range colder than the primary as set up OE on my 04Roadster. Before I installed my Techlusion at about 4000mi I checked the plugs and the secondary was exactly as you described...black, oily. I no like....
I installed NGK Iridiums at the same time and went one heat range hotter on the secondary, to try to keep the business end cleaner.
Both plugs looked much better when I checked again at my 6000mi service.
Primary=much more tan that bone white.
Secondary=still darker but much cleaner and more brown than black.
I'd try a hotter plug in there when you do the tune up....
 
Thanks guys for the input and here is my theory and I might check it out today. On the dual plug model the high voltage coils are integrated in each spark plug cap and both secondary plugs get high volts from a high volts coil up under the gas tank. If a failure happened to this coil under the tank the motorcycle would continue to run and perform much like its two plug predecessor. A couple of months ago I noticed a maybe 5 mpg drop in gas mileage and a drop in idle speed from about 1100 RPM to about 800 RPM. I really didn't pay much attention to this and decided to wait for 12K miles to look into it. Now I be thinkin that I have a bad secondary coil or a connection problem between this coil and the motronix. I came up with this theory from reading the Haynes manual that I have. Guess this is another reason I like these beemers, they are just fun to diddle with. Interesting your results with heat range plug change, hmmmmmm... Oh, Haynes gives resistance specs for this secondary coil. Primary winding resistance = 0.5 ohms Secondary winding R = 13Kohms for 850 & 1100 models and 7.5 Kohms for 1150 models.
 
Hey deep in the OH wasteland, I think I will follow your lead and switch to a hotter plug also. Pulled one of the secondary plugs and tested for spark and got good spark, whew :clap Thanks for your reply if it worked for you ought to work for me. Now to find an NGK plug in wonderful Florence by the sea. Not complaining because at least I don't have to shovel it. :)
 
Red100RT said:
Thanks guys for the input and here is my theory and I might check it out today. On the dual plug model the high voltage coils are integrated in each spark plug cap and both secondary plugs get high volts from a high volts coil up under the gas tank. If a failure happened to this coil under the tank the motorcycle would continue to run and perform much like its two plug predecessor. A couple of months ago I noticed a maybe 5 mpg drop in gas mileage and a drop in idle speed from about 1100 RPM to about 800 RPM. I really didn't pay much attention to this and decided to wait for 12K miles to look into it. Now I be thinkin that I have a bad secondary coil or a connection problem between this coil and the motronix. I came up with this theory from reading the Haynes manual that I have. Guess this is another reason I like these beemers, they are just fun to diddle with. Interesting your results with heat range plug change, hmmmmmm... Oh, Haynes gives resistance specs for this secondary coil. Primary winding resistance = 0.5 ohms Secondary winding R = 13Kohms for 850 & 1100 models and 7.5 Kohms for 1150 models.
Click to expand...

Interesting stuff, Red. I am experiencing some minor surging with my '04RT to the point I did a valve adjustment and TBS to try and smooth it out. I still have surging and the secondary plugs were black and oily. My mileage is in the high 30s. I guess I need to pull one of the secondaries and make sure I'm getting spark?
 
RT Guy, now that is interesting. When I pulled one of the secondaries yesterday and tested for spark and found I had a good strong spark I was relieved to be sure. I am going to install hotter plugs at the 18K service. I think that maybe the oil consumption during wear in of the rings may have fouled the original secondary plugs and may not have had the same effect on the primary plugs because of their location in the combustion chamber relative to the movement of the flame front?? I did relace all 4 plugs at 12K and have gone maybe 120 miles on the new plugs before doing spark check yesterday and the new plugs did not have a fouled appearance yesterday at all although the oil ring on the plug was fairly dark in color hence I will try a hotter plug. Good luck to you and your machine and tell us what you come up with.
 
Red100RT said:
Hey deep in the OH wasteland, I think I will follow your lead and switch to a hotter plug also. Pulled one of the secondary plugs and tested for spark and got good spark, whew :clap Thanks for your reply if it worked for you ought to work for me. Now to find an NGK plug in wonderful Florence by the sea. Not complaining because at least I don't have to shovel it. :)
Click to expand...

...check your PM for part numbers and places to buy.
:brow
 
jm, ordered plugs from sparkplugs.com and I actually had looked at their web sight but without the part number I was out of luck. Thanks again. :)
 
Red100RT said:
jm, ordered plugs from sparkplugs.com and I actually had looked at their web sight but without the part number I was out of luck. Thanks again. :)
Click to expand...

Yep...I found that out. Lots of places look at you very strangely if you ask for a NGK plug type DCHTX7XYZ...but give them the part number and voila'.
 
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