Srodden
Well-Known Member
Any reason for smaller plug gap ? CuriousCORRECT.........
I also like a .035" gap.
Spark Plug F Y I ...
- Thread starter cpmman
- Start date
BWG56
Guru
There's a reason why they recommend .040 and I'm sure its because they thought that would be a good number to pull outta their ass, and with that said at $1.50 ea, or a total of $3 for 2, I change them yearly
As a plug ages, and the metal of both the tip and hook erode, the gap will tend to widen; therefore experienced mechanics often set the gap on new plugs at the engine manufacturer's minimum recommended gap, rather than in the center of the specified acceptable range, to ensure longer life between plug changes. On the other hand, since a larger gap gives a "hotter" or "fatter" spark and more reliable ignition of the fuel-air mixture, and since a new plug with sharp edges on the center electrode will spark more reliably than an older, eroded plug, experienced mechanics also realise that the maximum gap specified by the engine manufacturer is the largest which will spark reliably even with old plugs and will in fact be a bit narrower than necessary to ensure sparking with new plugs; therefore, it is possible to set the plugs to an extremely wide gap for more reliable ignition in high performance applications, at the cost of having to replace or re-gap the plugs much more frequently, as soon as the tip begins to erode.
As a plug ages, and the metal of both the tip and hook erode, the gap will tend to widen; therefore experienced mechanics often set the gap on new plugs at the engine manufacturer's minimum recommended gap, rather than in the center of the specified acceptable range, to ensure longer life between plug changes. On the other hand, since a larger gap gives a "hotter" or "fatter" spark and more reliable ignition of the fuel-air mixture, and since a new plug with sharp edges on the center electrode will spark more reliably than an older, eroded plug, experienced mechanics also realise that the maximum gap specified by the engine manufacturer is the largest which will spark reliably even with old plugs and will in fact be a bit narrower than necessary to ensure sparking with new plugs; therefore, it is possible to set the plugs to an extremely wide gap for more reliable ignition in high performance applications, at the cost of having to replace or re-gap the plugs much more frequently, as soon as the tip begins to erode.
Letbigdogintocanada
Active Member
ILearned that the hard way,stay away from Iridium plugs,hahaJust an F Y I for those that may not have known. Below is a section right out of the 2003 Service manual....Could lead to some of the electrical issues some bikes see from time to time.
Do not use spark plugs other than the specified Champion brand.
FROM 2003 SERVICE MANUAL:
SPARK PLUGS
CHAMPION SPARK PLUGS, used as original equipment in all BIG DOG motorcycles, utilize a patented semi-conductor resistor to substantially reduce radio frequency interference (RFI) created each time the spark jumps across the gap of the spark plug. This RFI can result in starting and drivability problems, loss of performance and can even cause the ignition system module to completely shut down.
It is extremely important to use Champion resistor-type plug to ensure that the onboard computer that is the basis of BIG DOG motorcycle’s ignition system, is protected from this RFI.
Do not rely on industry standard cross-referencing to find an alternative brand of spark plugs to replace your CHAMPION OEM’s with. The replacement plugs may not be of a resistor-type.
Use only CHAMPION RN12YC in S&S motors and RA8HC in TOTAL PERFORMANCE
(TP) motors. Spark plug gaps are both .040”
TapioK
Well-Known Member
Oooo, the mentioned problem has nothing to do with how often you replace the plugs...
Sent from my iPhone using Tapatalk Pro
Chillin
Active Member
I have always used Autolite. Here is a quote from S&S......
"S&S has used the following spark plugs in V2-Style Long Blocks with good results: Autolite 4265, Champion RN12YC, Harley-Davidson 5R6A, and NGK BPR 4ES.
Install spark plugs with gap recommended by ignition manufacturer. Typically, .035-.045" is recommended for electronic ignitions."
Also the spark travels at the same speed reguardless of the gap, HOWEVER, this will
alter the ingition time slightly. Brought to you from the friendly folks at NASCAR.
Tighten gap for high RPM wider for low RPM, you can also change the heat range
of the plug for city or hot rodding, this will keep holes from forming in the piston.
"S&S has used the following spark plugs in V2-Style Long Blocks with good results: Autolite 4265, Champion RN12YC, Harley-Davidson 5R6A, and NGK BPR 4ES.
Install spark plugs with gap recommended by ignition manufacturer. Typically, .035-.045" is recommended for electronic ignitions."
Also the spark travels at the same speed reguardless of the gap, HOWEVER, this will
alter the ingition time slightly. Brought to you from the friendly folks at NASCAR.
Tighten gap for high RPM wider for low RPM, you can also change the heat range
of the plug for city or hot rodding, this will keep holes from forming in the piston.
Last edited:
Letbigdogintocanada
Active Member
I thought so to,until I swapped them for some Champions, what a difference, Scoot started to run crappy,i thought it was bad fuel,read up on a few threads to stay with the recommended brand,so I did all ,bike runs like a million bucks,iam convinced, lol
PacoPetty
Well-Known Member
You complete me!There's a reason why they recommend .040 and I'm sure its because they thought that would be a good number to pull outta their ass, and with that said at $1.50 ea, or a total of $3 for 2, I change them yearly
As a plug ages, and the metal of both the tip and hook erode, the gap will tend to widen; therefore experienced mechanics often set the gap on new plugs at the engine manufacturer's minimum recommended gap, rather than in the center of the specified acceptable range, to ensure longer life between plug changes. On the other hand, since a larger gap gives a "hotter" or "fatter" spark and more reliable ignition of the fuel-air mixture, and since a new plug with sharp edges on the center electrode will spark more reliably than an older, eroded plug, experienced mechanics also realise that the maximum gap specified by the engine manufacturer is the largest which will spark reliably even with old plugs and will in fact be a bit narrower than necessary to ensure sparking with new plugs; therefore, it is possible to set the plugs to an extremely wide gap for more reliable ignition in high performance applications, at the cost of having to replace or re-gap the plugs much more frequently, as soon as the tip begins to erode.