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VRSCX #395
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Discussion Starter · #1 ·
going to run a set of ngk dcpr8 what gap you guys running on these, i noticed the center electrode protrudes out more than the hd plug is this ok? hd recommends .035 gap on there plug.
 

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Color me Gone
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Yes run the .035 gap.
 

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I am running the iridium plugs. I went with the NGK recommended gap of .040.
Beware that these plugs are very fragile and even the smallest gap measuring touch can break the center electrode!:banghead:
 

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I've always run the NGK plugs......on everything from daily driven cars/trucks to all out nitrous huffing dragbikes......

.035 is the gap on standard compression/no nitrous motors.....
.024 on nitrous or ultra high compression motors(16.5 to 1+)......
 

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VRSCX #395
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Discussion Starter · #5 ·
thanks guys .035 it is, had 8 left over from when i had my softail found 2 i could index, so i should go quicker in my mind anyway
 

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Color me Gone
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rogerdata said:
I don't mean to be argumentative but I did not post this without checking first. Please see the jpg below. The info can be found at http://www.ngksparkplugs.com/apps/motorcycles/make4.asp?id=848&type=ir
Roger:D
Your right they call for a 0.04 gap from ngk. The v-rod calls for a 0.035 gap using Harley's plug. I think either way your safe but in years past I have learned that gaps too wide can cause a low rpm stumble in many engines so that is the reason I suggested the same gap that Harley calls for. I also run ngk plugs in mine and have mine gapped at 0.035 and the last set I installed in rspencers bike came gapped at 0.035 and we only checked them before we installed them. Either way I think he is safe with either gap and no one was saying you were wrong by any means.
 

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rogerdata said:
I am running the iridium plugs. I went with the NGK recommended gap of .040.
Beware that these plugs are very fragile and even the smallest gap measuring touch can break the center electrode!:banghead:
just a caution. sometimes platinum or iridium spark plugs can fool the knock sensor into thinking the motor is detonating . if you loose power when you put them in this is why. i have seen some spark plugs cause the ion sense to pull so much timing that the motor is down 20 hp. of course you can disable the knock sensor with the sert.
 

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Both Max and ibrown may be right!:notworth:
Yesterday I did experience low RPM stumble also the bike was just dyno'ed and I think the Horsepower was somewhat low at SAE 98.79 HP and Max torque 66.75. We did achive a good curve and a pretty flat line for AF. Another reason for my concerns is that the exhaust discs (supertrapps) are showing quite a bit of black powder residue. I need to pull these plugs and have a look at them. I may even go back to stock ones and re-dyno. I plan on sharing my powercommander map as soon as I can get this sorted out. I have attached the dyno sheet here.:banghead:

Forgot to include my specs.
07 Night Rod Special
Powercommander
SE filter Top On
Supertrapp Universals with 12 discs
 

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one reason i prefer the sert is using the data mode to record dyno runs. you can learn a lot by studying the data. one help is it shows if the ion sense is pulling timing out. also with a power commander you can be fooled when tuning. sometimes your a/f will show rich and you will take out some fuel with the pwr cmder only to see the a/f reading get richer. what happened? well when the knock retard pulls out timing so you burn less of the fuel and get a richer a/f reading. also the power is dropping badly. the sert data mode would have clued you in. also some engine combinations will fool the ion sense(knock sensor) and you will never make any hp without disabling it. you can only do that with the sert.
 
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