Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[SPIDERMAN]

Looking for a consensus on sparkplug gaping here. I've always gapped my plugs wide( .045 -.050)  Sometimes starts a bit harder, but I'm of the opinion it creates a fatter spark.

COMMENTS ?

B B

[hd-dude]

I've always ran them at .040.  The larger the gap the more voltage it takes to bridge the gap so a larger gap would create a longer spark but also a less intense (weaker) spark unless the voltage output of the coil is increased to compensate. Race motors typically use a large gap and very high output coils.

[Twolanerider]

40 thou here too Brian.

[grc]

Brian,

Assuming the rest of the ignition system is capable of consistently firing the wider gap, the wider gap is preferable to a narrow gap.  This is especially true with stock (lean) air/fuel ratios, and the rationale is that a wider gap improves the odds that a combustable mixture will be located within the gap.  In the "bad old days" of auto emission systems and carburetors, we had ignition systems that could fire gaps of .080" or more for this very reason.

Personally, I like to set my plugs near the max of the specified range (ie. a loose .040" / snug .045" with a spec of .038"-.043").  Since I change plugs yearly, I don't have to worry about electrode erosion causing the gap to grow to the point of misfire.  Anything wider, however, may have adverse effects on starting and high rpm operation.  If you go to a fine wire plug like the Autolite or the Iridium, you can open the gap a little more since the fine wire electrode reduces the amount of voltage required to fire the plug. 

Jerry

[SPIDERMAN]

I run Screamin Eagle Triple Plaitinum plugs and toss em every fluid change (2,500)

SE coil and plug wires to fire em. Sounds like I'm good at .045

Thanks

B B

[Twolanerider]

I run Screamin Eagle Triple Plaitinum plugs and toss em every fluid change (2,500)

SE coil and plug wires to fire em. Sounds like I'm good at .045

Thanks

B B

Brian, if you change fluids at 2500 do you just use a good dino oil?  Or still use synthetics?

[SPIDERMAN]

Brian, if you change fluids at 2500 do you just use a good dino oil?  Or still use synthetics?

I'm an old fashioned guy in love with new technology Don. I use Amsoil and toss it every 2,500 miles (all 3 holes)     Old habits die hard buddy, but ask Mark what kind of shape Elvis is in with 40k on the odometer. Long time ago, someone told me " oil is cheap, new engines aren't "

B B

[Twolanerider]

I'm an old fashioned guy in love with new technology Don. I use Amsoil and toss it every 2,500 miles (all 3 holes)     Old habits die hard buddy, but ask Mark what kind of shape Elvis is in with 40k on the odometer. Long time ago, someone told me " oil is cheap, new engines aren't "

B B

Brian, service intervals on bikes, religion, political parties, breasts or bottoms; it's all whatever works for you man.  You'll never hear me say a word.  It doesn't break the bank and you're good with it.  That's all that matters.

[rednectum]

something to consider on spark gap. the ionic sensor is looking for resistance at the plug, if it determines resistance, it will retard timing.a longer gap would provide this resistance. larger gap also makes the motor feel like it has a little extra timing----go figure , the ion sensor sees resistance and retards timing that was added by increasing gap----any benefit?

the real logic behind the ion sensor was to pull timing during detonation, which it sees as resistance at the plug.

[SPIDERMAN]

something to consider on spark gap. the ionic sensor is looking for resistance at the plug, if it determines resistance, it will retard timing.a longer gap would provide this resistance. larger gap also makes the motor feel like it has a little extra timing----go figure , the ion sensor sees resistance and retards timing that was added by increasing gap----any benefit?

the real logic behind the ion sensor was to pull timing during detonation, which it sees as resistance at the plug.

Something to consider indeed. Thanks for the post. I'm gonna run a set of plugs at .040 and see how LD runs.

B B