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Old 06-07-2009, 08:39 PM
Retmachinist's Avatar
Retmachinist Retmachinist is offline
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Join Date: Oct 2008
Location: Urbandale Ia
Posts: 637
Thumbs up Spark Plug Gap!

I have noticed alot of discussion on different spark plug gaps on the forum. Most people seem to go with .020-.025. I have done alot of experimenting with different plugs and gaps.
For me .035 with an N.G.K. B5HS seems to be the best by far. I also noticed that my latest engine from Grubee actually had a manual with a few specs. They suggest a .036 gap.
What do the rest of you find works the best, just curious?

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Old 06-07-2009, 09:59 PM
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Dave31 Dave31 is offline
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Join Date: Mar 2008
Location: Old Pueblo,Arizona
Posts: 11,118
Default Re: Spark Plug Gap!

I run .023

But, I have ran as much as .038. I don't remember because it's been a while, but for some reason I settled with .023

When I installed Normans light I went down to .018, but I am back at .023 again.
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Old 06-08-2009, 12:23 AM
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Junster Junster is offline
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Join Date: Jun 2009
Location: Washington St.
Posts: 446
Default Re: Spark Plug Gap!

I have a slandhead and I found it runs better with a colder plug. I also filed the electrode to a semi point. It exposes more of the fire area. I use a b7hs gapped at .035. I read about the "point fire" thing in another thread here. It's working well for me. I have noticably better torque. I was using a b5hs.
Put something FUN between your legs..
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Old 06-18-2009, 12:47 PM
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JD-StukNchaoS JD-StukNchaoS is offline
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Join Date: Dec 2008
Location: santa paula, Calif.
Posts: 31
Default Re: Spark Plug Gap!

Glad to see that many of the peddler fanatics .,like myself are actually utilizing my tech tips that were shunned from the start, but later found to be helpful and true when it came to the wot flutter and tweeking the gap basically eliminating many issues. How some of the fine tuning can be utilized by gap settings. At the time i gave my input on this subject of gapping for performance i was literally here less than a week, replied to members comment on wot flutter heard what mods he had done , knew where the motor break in was at and told him to only mix enough fuel to last 2 weeks max, go 32:1 ratio, and replace your plug w/ ngk b5hs and gap it at .035-.042 but start at the low and progressively increase based on 2 things: ride hard stop check plug color, then increase accordingly, then stop when you've peaked at wot ,.,.pretty basic stuff! Timing and duration of spark,.But i got slammed on the gap setting by a few that were still using their factory plug,.,.haha that kill more motors than a kid pinning it on his 1st lap during breakin. I've done many of the same mods here with MB's and the hi perf. techniques that i've been doing to my 2-stroke air and h2o cooled engines that are pushin' 16hp in a pocketbike for almost 30 yrs. ,..,.ride-on
Nothing runs like a deere

Last edited by JD-StukNchaoS; 06-18-2009 at 12:57 PM.
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