HELP READING SPARK PLUG AFTER MODS
#1
03-16-2002, 04:27 PM
Join Date: Feb 2002
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I recently installed a Yosh slip on exhaust, K&N filter, dynojet 146-148 combo on my raptor. Quad runs strong....nice improvement. When i pulled the spark plug the electrode was a nice medium brown but what concerns me is that it was not a uniform color. About 1/4 of the electrode was white. Has anyone else had this problem. I set everthing to dynojets specs. In the back of my mind i'm thinking that one of the carbs is too lean. Why isn't the electrode a 100% color. Any / all insight will help....
#2
03-16-2002, 04:33 PM
From what I have been told the plug should have a slight black color to it. It Sounds like you are running very lean. When I installed my dynojet kit I ended up running to rich. The directions for me used the dj144 & dj146 jets. The clip positions were 4 down from top. Later dynojet personal told me because I was running rich to go to the 2nd position down from the top. This made a big diffrence for me, but still a little rich .
#3
03-16-2002, 04:43 PM
#4
03-16-2002, 06:04 PM
#5
03-16-2002, 11:10 PM
<< [i]It is very difficult to impossible to read plugs when using pump gas. TRUE!Also,I would get a magnifying glass and get a look at the bottom of the porcelain down in the plug. Most jetting companys give you a "baseline" jetting recomendation,it's up too you to get it tweaked in.Plus,its hard to tell which jet is giving it the lean/rich color effect.It could be the main or the pilot???I usually go with the "ride and feel method" and bump my jets up/down one increment at a time.If you go to Eric Gorr's website.He has a good carb tuning guide under the Technical Article.
#6
03-17-2002, 02:53 AM
the closest way to get a reading is to run your quad at speed for a couple minutes and while your running kill the engine and then coast to a stop. or use your brakes or whatever. that's the best way i know of. if you let off the gas before you kill it or down shift your reading will be off.
#7
03-17-2002, 05:53 AM
<< the closest way to get a reading is to run your quad at speed for a couple minutes and while your running kill the engine and then coast to a stop. or use your brakes or whatever. that's the best way i know of. if you let off the gas before you kill it or down shift your reading will be off. >>
Thats called a WOT test(wide open throttle)and it's only going to give you an accurate reading on your main jet.I would suggest putting in a new plug and riding in circles at 1/4 and 1/2 throttle to get a look at what your pilot circuit is doing.
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#8
03-17-2002, 09:42 PM
#9
03-18-2002, 12:13 AM
( I know this is long, but I hope you feel it was worth it )
PLUG READING
TO READ PLUGS PROPERLY YOU WILL NEED A 10x ILLUMINATED MAGNIFYING GLASS
This is how it's done!!!
1. You set your heat range from the ground strap. ( this is the piece closest to the piston )
2. You do all the plug readings for jetting from the base ring ( the base ring is where the
ground strap is welded too )
3. You determine detonation and timing issues from the porcelain. The porcelain shows preignition/detonation, it will not accurately determine jetting / air/fuel ratios.
DO NOT BASE JETTING DECISIONS ON THE PORCELAIN COLOR.
1. How to determining plug heat range:
The ground strap is your window to getting this right. If the "color" of the ground strap "changes" too-close to the ground-strap's end, ( the end opposite of the base ring ), then the heat-range is "too-cold" , ( heat transfer is to quick to the base ring ) If the "color" of the strap changes near where it is welded to the base-ring, then it means that the plug heat-range is "too-hot", ( heat transfer to the base ring is to slow causing the deposits to be burned off the strap completely ) The strap at this point could start working like a "glow-plug", probably resulting in pre-ignition/and/or detonation. The Properly set heat-range is when the "color" is at the half-way point on the strap.
2. Reading the base ring to determan jetting:
The base ring " color " is very close to the color of the piston crown and is used to determan the jetting. Your looking for the soot color to be a nice light to medium brown, ( color is always hard to discribe ) if the color doesn’t go all the way aroung the base ring or the color is whitish it is way too lean. If the color goes all the way around, but there is a spoting of heavy dry soot on the top of the color, you are too rich. ( TWO STROKE JETTING WILL BE A LITTLE WETTER LOOKING AND DARKER THEN A FOUR STROKE )
3. Read the porcelain to determine detonation / preignition
The first signs of detonation / preignition will be seen on the porcelain down in the plug, It shows up as tiny black or shinny specks of aluminum. Also Look very close around the center electrode where the porcelain intersects this will appear to be melting between the insulator and the electrode.
Detonation is caused by the air/fuel mixture exploding rather then burning. This gives off a sound, ( a knock ) this sound is the result of a shock wave, this wave disrupts the boundary layer of cooler gasses that cover the internal parts of the combustion chamber. This causes a very rapid rise in pressure and temperature. The results, holes in the top or sides of the pistons, blown head gaskets, broken rods, ( all bad stuff ) This can also shock the rings from there seal causing oil to form as little spots on the porcelain.
PLUG READING
TO READ PLUGS PROPERLY YOU WILL NEED A 10x ILLUMINATED MAGNIFYING GLASS
This is how it's done!!!
1. You set your heat range from the ground strap. ( this is the piece closest to the piston )
2. You do all the plug readings for jetting from the base ring ( the base ring is where the
ground strap is welded too )
3. You determine detonation and timing issues from the porcelain. The porcelain shows preignition/detonation, it will not accurately determine jetting / air/fuel ratios.
DO NOT BASE JETTING DECISIONS ON THE PORCELAIN COLOR.
1. How to determining plug heat range:
The ground strap is your window to getting this right. If the "color" of the ground strap "changes" too-close to the ground-strap's end, ( the end opposite of the base ring ), then the heat-range is "too-cold" , ( heat transfer is to quick to the base ring ) If the "color" of the strap changes near where it is welded to the base-ring, then it means that the plug heat-range is "too-hot", ( heat transfer to the base ring is to slow causing the deposits to be burned off the strap completely ) The strap at this point could start working like a "glow-plug", probably resulting in pre-ignition/and/or detonation. The Properly set heat-range is when the "color" is at the half-way point on the strap.
2. Reading the base ring to determan jetting:
The base ring " color " is very close to the color of the piston crown and is used to determan the jetting. Your looking for the soot color to be a nice light to medium brown, ( color is always hard to discribe ) if the color doesn’t go all the way aroung the base ring or the color is whitish it is way too lean. If the color goes all the way around, but there is a spoting of heavy dry soot on the top of the color, you are too rich. ( TWO STROKE JETTING WILL BE A LITTLE WETTER LOOKING AND DARKER THEN A FOUR STROKE )
3. Read the porcelain to determine detonation / preignition
The first signs of detonation / preignition will be seen on the porcelain down in the plug, It shows up as tiny black or shinny specks of aluminum. Also Look very close around the center electrode where the porcelain intersects this will appear to be melting between the insulator and the electrode.
Detonation is caused by the air/fuel mixture exploding rather then burning. This gives off a sound, ( a knock ) this sound is the result of a shock wave, this wave disrupts the boundary layer of cooler gasses that cover the internal parts of the combustion chamber. This causes a very rapid rise in pressure and temperature. The results, holes in the top or sides of the pistons, blown head gaskets, broken rods, ( all bad stuff ) This can also shock the rings from there seal causing oil to form as little spots on the porcelain.
#10
03-18-2002, 12:26 AM
