Spark plug modification.

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wayne z

wayne z

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Dec 5, 2010
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Yea prolly makes no difference at all. But like you said in an earlier post, many like to tinker with their plugs, and I posted about those plug mods to add to the other tecniques in this thread for those that like to tinker.

It is your opinion that plugs don't make a difference, but some of us like to have fun experimenting, and draw our own conclusions

My first HT build was stolen last month, and I got my new one from BGF fri.
Got a new Macargi cruiser coming next week. Soon as I get it built and running good I'm gonna do a comparison test with the HT plug vs a NGK with my mods, and I will post my results.

I will post a pic of my stolen bike after one more post.
 
wayne z

wayne z

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Dec 5, 2010
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OK, I been in the basement cleaning up the intake and exhaust welds with a dremel and carbide bit.

Checked every screw even inside the mag cover and they were all loose:~)

My new engine is a slant head and the top of sparkplug points rearward. This looks backward to me. which way are most with slant heads running them?

Thanks, Wayne Z
 
J

jauguston

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May 1, 2010
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Bellingham, WA
Wayne,

The head and combustion chamber are symmetrical so you can rotate it any way that works best for your installation. On mine overhead clearance was tight so I turned the plug to face forward.

I am all for experimentation its fun. To make it a worthwhile venture you need a way to quantify the results. For engine modifications the only repeatable way to know what you did made a difference is a dynomometer. My butt dyno is not accurate enough to tell if minor changes make any difference better or worse especially when you are working on a engine that has very little power to start with.

Jim
 
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bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
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the way i see this issue, is i indexed plugs on every car i've owned, and used to file the tips of the plugs (and the rotor) on my autocrosser, so why shouldn't i do it to my bike?

it's been proven to work on other motors, so even if i can't tell that i've got 87/10Oths of a performance increase, every little bit helps, right?

it all adds up to that 1 extra mile an hour.

plus, if it doesn't work, it ain't hurting anything.
 
J

jauguston

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May 1, 2010
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Doesn't hurt a thing thats for sure. My thinking is if we want to see if we can get a little more power out of a HT that wouln't be where I would look first. I get the feeling the reason so much time is spent trying to gain power by fooling with a spark plug is anyone with zero mechanical knowledge can mess with it without screwing anything up.

Jim
 
bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
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my thinking is before trying to bolt on power with an expansion chamber or a carb, the motor should be tuned right and dialed in.

finding the right plug, the right gap, and tweaking it for 5 minutes is just another small thing to do in that process.

i'm not saying that buying some fancy 3 prong plug or whatever gimmick of the month plug (like the splitfire. the only thing those plugs did was destroy your motor when the tip split apart) i mean, i use an NGK B7HS and dial it in to my motor.

what i am saying, is a good plug, a good wire, clean and soldered contacts is the way to go.
 
J

jauguston

New Member
May 1, 2010
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I agree a motor needs to be tuned properly to do its best. My issue is there is no tuning to a sparkplug as long as it is the right heat range and that you can tell by the color of the porcelain. From what I have found with mine the big improvements in performance have come from jet changes and needle height changes. The stock HT carb mine says SPEED on the side are way too rich all the way through the throttle range. Sick Bike Parts has jets. My carb had a 70 jet in it. It now has a 66. Needle clip in the top groove. OPTI-2 oil at 100-1 since day one.

Jim
 
wayne z

wayne z

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Dec 5, 2010
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Yea you're right. Mine didn't run good with any plug until I soldered the #70 jet, and drilled it out by experimenting with torch tip cleaning twist bits.
The kind that you can get from NAPA.
Started with the .018, too lean
.023 works great, fine tuned with needle clip.Just barely 4 strokes when wound out,and plug chop shows chocolate color.

Wayne Z
 
caduceus

caduceus

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Feb 4, 2009
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Frostbite Falls, MN
Back in the early 1970s we used to service spark plugs when we tuned up a car. We'd bend the ground strap back enough to get a small flat file square on the center electrode and take enough off of the center electrode to provide a sharp edge all around. Then reset the gap, apply fresh anti-seize to the threads, and reinstall the spark plugs.

The sharp edges of the center electrode will round off over time due to vaporization from the heat of many millions of sparking events, and a rounded-off electrode requires more voltage to ionize the air gap and provide a path to ground.

With the advent of breakerless ignitions and higher voltages available this practice has ceased to be practical for automobiles and most motorcycles. The prevalence of carbon tracks and carbonization of plastic distributor rotors in the early GM breakerless ignitions was legendary for causing a car to come limping in with only five or six cylinders firing out of eight.

However, I find that servicing the spark plug on my little GHX50 Honda makes it idle and accelerate more smoothly. Probably due to the limited voltage available from the miniaturized ignition. Just two cents from an old mechanic.
 
Goat Herder

Goat Herder

Gutter Rider
Apr 28, 2008
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akv4590 said:
Sweet! It worked! It was righty loosey though. The NGK BPR7HIX plug I replaced it with uses 13/16ths. The new plug sticks down lower than the stock one though so I'm going to roll the wheel for a bit tomorrow to see if it hits the piston or anything. Hopefully every goes exactly as planned.....
Click to expand...
You sure that was not lefty loosy;)
 
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