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Alaskavan
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Humor aside. Good info Augie. Thanks. And thanks Doc for making us think about this.
What replacement spark plugs do you use? (chinese 2-stroke)
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gone_fishin
Guest
this very thread keeps coming up on my searches...guess there's not a lot of nhsp discussion going on...
heads are from dax 70...lousy pic, sorry...
left: nhsp ld z4c (slightly short)
right: ngk b6hs (flush)
decent info:
http://www.nhsp-ld.com/en/News/ShowInfo2.aspx?ID=10
found this, it's actually pretty helpful:
View attachment chart_sorta.doc
i took the price sheet above and searched "torch 4114" & came up with this:
the torch 4114 & ngk 5858 seem short (11mm)...the Bosch W4AC (i think) is just right...here, it cross-references an NGK B8HS (NGK: higher=colder): http://www.bayshorecad.com/Sleds/SparkPlugIndex.html
'nother good reference chart: http://www.kartingtechinfo.com/tech/plug.htm
my conclusion (read: opinion) for a dax 70: 14mm thread, 12mm reach, medium heat range, .028 gap...based on application & suitability, NOT on higher performance...
Bosch W4AC
Champion L78C
NGK B8HS
heads are from dax 70...lousy pic, sorry...
left: nhsp ld z4c (slightly short)
right: ngk b6hs (flush)
decent info:
http://www.nhsp-ld.com/en/News/ShowInfo2.aspx?ID=10
found this, it's actually pretty helpful:
View attachment chart_sorta.doc
i took the price sheet above and searched "torch 4114" & came up with this:
the torch 4114 & ngk 5858 seem short (11mm)...the Bosch W4AC (i think) is just right...here, it cross-references an NGK B8HS (NGK: higher=colder): http://www.bayshorecad.com/Sleds/SparkPlugIndex.html
'nother good reference chart: http://www.kartingtechinfo.com/tech/plug.htm
my conclusion (read: opinion) for a dax 70: 14mm thread, 12mm reach, medium heat range, .028 gap...based on application & suitability, NOT on higher performance...
Bosch W4AC
Champion L78C
NGK B8HS
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Scottm
Guest
Just to think, before I bought this DAX 50cc, I only bought spark plugs for lawn mowers. I never thought I'd be learning so much. Thanks for all the great info.
The NGKB8HS I bought was gapped at .020 and the factory plug onmy motor was at .030. So your .028 falls in that range safely.
Thanks again.
Scott
The NGKB8HS I bought was gapped at .020 and the factory plug onmy motor was at .030. So your .028 falls in that range safely.
Thanks again.
Scott
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Dockspa1
Guest
Augi, so if I got this right, a wider gap will cause the fuel to burn quicker then a narrower gap? That is what makes the engine hotter or cooler?
This might be finally sinking into my thick scull.
The speed of the combustion is based on the spark gap.
I guess when you consider how fast those combustions are I guess it could make sense.
Thanks
Oh, one more question, why do they sell hot or cold plugs but keep the same gap?
Doc
This might be finally sinking into my thick scull.
The speed of the combustion is based on the spark gap.
I guess when you consider how fast those combustions are I guess it could make sense.
Thanks
Oh, one more question, why do they sell hot or cold plugs but keep the same gap?
Doc
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gone_fishin
Guest
all only opinion:
heat range is a matter of all the factors...intended operating temp of the engine, kind of fuel used, the operating environment...that's why i posted the seemingly irrelevant ngk info...great lil education on heat-range.
gap is a matter of voltage...i've averaged out all the info i could find plus my own experience with the gaps and plugs i've used on my happy-time.
i've decided it's best to get the heat OUT of the combustion chamber and to the cooling fins as quickly as possible, hence my opinion that we need to go with a cooler (more heat dissipating) plug.
the gap is based on me knowing that the magneto/cdi will spark across .030...so for surety i recommended .028 (which is a very common plug gap)...i no longer want to go after the smaller (more intense ignition) gap...i WANT some of that oil to be unburned...with my new philosophy, i now have that thin layer of unburnt oil inside the combustion chamber again...smokes a bit during warm-up (i find it comforting to see, lets me know i'm onto something) and within about 3 miles i'm up to temp, running great (not crazy great, just reliable) and no smoke. i think i'm in the ballpark with this, would love some real-time feedback.
heat range is a matter of all the factors...intended operating temp of the engine, kind of fuel used, the operating environment...that's why i posted the seemingly irrelevant ngk info...great lil education on heat-range.
gap is a matter of voltage...i've averaged out all the info i could find plus my own experience with the gaps and plugs i've used on my happy-time.
i've decided it's best to get the heat OUT of the combustion chamber and to the cooling fins as quickly as possible, hence my opinion that we need to go with a cooler (more heat dissipating) plug.
the gap is based on me knowing that the magneto/cdi will spark across .030...so for surety i recommended .028 (which is a very common plug gap)...i no longer want to go after the smaller (more intense ignition) gap...i WANT some of that oil to be unburned...with my new philosophy, i now have that thin layer of unburnt oil inside the combustion chamber again...smokes a bit during warm-up (i find it comforting to see, lets me know i'm onto something) and within about 3 miles i'm up to temp, running great (not crazy great, just reliable) and no smoke. i think i'm in the ballpark with this, would love some real-time feedback.
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Dockspa1
Guest
Well, Augi, I think I get the gest of it with your patient explanations and explorations.
It sounds like .028 is a safe gap and the cooler plug would be best.
Boy, I hope there's not going to be a test on this tommorrow!
Thanks again.
Oh! just one more question, na, just kidding!
Oh, Van your welcome but I just put the (Spark) everyone else lit it up.
It sounds like .028 is a safe gap and the cooler plug would be best.
Boy, I hope there's not going to be a test on this tommorrow!
Thanks again.
Oh! just one more question, na, just kidding!
Oh, Van your welcome but I just put the (Spark) everyone else lit it up.
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gone_fishin
Guest
it took me the better part of a year, but i'm focusing on longevity & reliability...i can't afford "performance" & apparently neither can the happy-times-two 
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cruisinkruty
Guest
Spark plug info:From a real gear head
I see alot of people concerned with the reach of there plugs. This is critical. If the plug is recessed into its hole you are losing compression by making the combustion chamber larger. Consequently if the plug protrudes into the combustion chamber a wee bit you are effectivly creating a smaller chamber space and upping the compression. The higher the compression the more power,period.Once your compression ratio exceeds 9.5 to 1 you will need premium fuel of at least 93 octane to stop detonation. Octane is the fuels resistance to detonate or self ignite.These engines incorporate a hemispherical combustion chamber which is the best design to prevent detonation. Lawnboy 2 cycle engines have a similar combustion chamber and employ a champion CJ14. It has a 1/2 inch reach. Most of your domestic air cooled lawnmower engines use a spark plug with a 1/2 inch reach. Heat range on spark plugs is determined by the length of the center electrode. The longer the center electrode,the longer the path to the main meat of the plug and the hotter the tip stays.If the tip"center electrode" is short it has a close path to dissapate its heat into the meat of the plug causing the tip to run cooler. Too hot of a plug and the tip will actually glow red and cause ignition of the fuel prematurely just as the piston is reaching TDC,its kinda like having the ignition timing too far advanced.
I see alot of people concerned with the reach of there plugs. This is critical. If the plug is recessed into its hole you are losing compression by making the combustion chamber larger. Consequently if the plug protrudes into the combustion chamber a wee bit you are effectivly creating a smaller chamber space and upping the compression. The higher the compression the more power,period.Once your compression ratio exceeds 9.5 to 1 you will need premium fuel of at least 93 octane to stop detonation. Octane is the fuels resistance to detonate or self ignite.These engines incorporate a hemispherical combustion chamber which is the best design to prevent detonation. Lawnboy 2 cycle engines have a similar combustion chamber and employ a champion CJ14. It has a 1/2 inch reach. Most of your domestic air cooled lawnmower engines use a spark plug with a 1/2 inch reach. Heat range on spark plugs is determined by the length of the center electrode. The longer the center electrode,the longer the path to the main meat of the plug and the hotter the tip stays.If the tip"center electrode" is short it has a close path to dissapate its heat into the meat of the plug causing the tip to run cooler. Too hot of a plug and the tip will actually glow red and cause ignition of the fuel prematurely just as the piston is reaching TDC,its kinda like having the ignition timing too far advanced.
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gone_fishin
Guest
awww...i thought i was real, too...at least i felt real when i was doing my research
yup, on the chinese 2-stroke, cooler is best. and the proper reach, for the reasons you've laid out, seems to be 12mm, at least for all the heads i've seen firsthand
yup, on the chinese 2-stroke, cooler is best. and the proper reach, for the reasons you've laid out, seems to be 12mm, at least for all the heads i've seen firsthand
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davidsis
Guest
Best plug
So bottom line what is the best plug, and gap setting????????????????
Im tired of my Champion CJ7Y just stoped running right and my bike won't run unless the gap is paper thin. What is the best plug
NGK B6HS & B5HS
Champion L86C
Champion CJ7Y low profile ( I like these)
Autolite 425
ND W2OFS_U
Bosch W9EO
or other ones that were mentioned. I just want a regular plug, no high performance please. I now think the Champion CJ7Y bites the big one. I feel more confused than before I started trying to find a plug in the first place.
So bottom line what is the best plug, and gap setting????????????????
Im tired of my Champion CJ7Y just stoped running right and my bike won't run unless the gap is paper thin. What is the best plug
NGK B6HS & B5HS
Champion L86C
Champion CJ7Y low profile ( I like these)
Autolite 425
ND W2OFS_U
Bosch W9EO
or other ones that were mentioned. I just want a regular plug, no high performance please. I now think the Champion CJ7Y bites the big one. I feel more confused than before I started trying to find a plug in the first place.
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