spark plug pics

[Felix]

I've been running my new nt carb after thrashing the cns v3 carb that came with the kit. I noticed the throttle wasent as "crisp" as the cns. So i moved the carb needle to its highest point(leanest i think), it was at second from the top originally. Didnt know if that would have an affect or not but the throttle response is great now. The spark plug was a little "wet" looking in the second point but in its setting now I think I might be running it a bit hot.

a little blury

Also I was able to reach 23 mph with my cns carb but only 20 on the nt. Starts making different sound on the top end. I think thats what their calling 4 stroking. I think i read the main jet comes in 70mm. Should I get a 72mm, would that make the 4 stroking go away and mabey a hight speed? Thanks!

 

[2door]

If you feel it is "four stroking" you don't want a bigger jet. Four stroking is usually a symptom of a rich condition but your plug looks a little lean. Are you sure it is four stroking or starving for fuel at WOT?

Also keep in mind that the needle only controls fuel flow up to about 3/4 throttle. Anything after that is determined by the main jet orifice size.

What is your altitude (above sea level) ?

Tom

 

[Felix]

If you feel it is "four stroking" you don't want a bigger jet. Four stroking is usually a symptom of a rich condition but your plug looks a little lean. Are you sure it is four stroking or starving for fuel at WOT?

Also keep in mind that the needle only controls fuel flow up to about 3/4 throttle. Anything after that is determined by the main jet orifice size.

What is your altitude (above sea level) ?

Tom

I'm not sure which it is. If it is starving for fuel at wot, how would i know and how can i fix it?

What jet size would be better?

I live in Texas, on the southern tip close to mexico. So altitude? I dont know.

Thanks for you help 2door.

 

[2door]

How many miles would you say is on the plug in your photo? The color of the porcelain appears to be on the light side telling me you are running a tad lean. Preferably you'll want that plug to be more of a chocolate brown color as opposed to white or grey. The lighter the color the leaner the fuel to air mix.

My guess is you need a little larger jet size. I don't go by jet numbers. My experience is they are nebulous at best. I solder and re-drill and experiment until I get the performance I want.

If you give me a city, or the name of the closest airport, I'll tell you your elevation. That plays heavily into tuning for best performance.

Tom

 

[GearNut]

What brand/ type of pre-mix oil are you using?
Some don't color a spark plug in shades of brown but rather in shades of grey due to the different blends of lubricants involved.
I need to know this info before I make a decision on the color of the porcelain.

I like your front motor mount, BTW.

 

[Felix]

How many miles would you say is on the plug in your photo? The color of the porcelain appears to be on the light side telling me you are running a tad lean. Preferably you'll want that plug to be more of a chocolate brown color as opposed to white or grey. The lighter the color the leaner the fuel to air mix.

My guess is you need a little larger jet size. I don't go by jet numbers. My experience is they are nebulous at best. I solder and re-drill and experiment until I get the performance I want.

If you give me a city, or the name of the closest airport, I'll tell you your elevation. That plays heavily into tuning for best performance.

Tom

I have 150 miles on the spark plug, they pulg was darker making the tip have a "wet" look when the needle in the carb was at the second notch from the top.

lol I tried my first attemted at soldering last week didnt go so well. But defenitly going to go there again if i need too.

I live in a Donna, Tx. Nearest airport is in Macallen, about 15 min away.

Really apreaciate your help 2door.

 

[Felix]

What brand/ type of pre-mix oil are you using?
Some don't color a spark plug in shades of brown but rather in shades of grey due to the different blends of lubricants involved.
I need to know this info before I make a decision on the color of the porcelain.

I like your front motor mount, BTW.

Right now i'm using lucas semi-senthtic at 50:1. Only because i couldnt find the opti-2 i was looking for. But located some at a hardwared store about 28 miles from me. Going by there tomorrow and picking some up. They have the 1 galon sized pouch giving me a ratio of 100:1, which i read up in the "1000 miles" thread.

Thanks, I got that motor mound from gasbike.net.

Thanks for your help GearNut

 

[GearNut]

Now that I know what oil you are using, I say that your plug indicates a good air fuel mixture and it is a good heat range too.
Still that is not the end-all of proper tuning. Keep with the re-jet/ solder-n-drill technique until you can get the engine to run better at near to and full throttle positions.
4 stroking is caused by too much fuel being added to the incoming intake air, too rich.
If the engine sounds like it runs very well at the highest RPM's but seems to have no power then there is not enough fuel being added to the incoming intake air, it is too lean.
This will also cause very serious damage to the piston and cylinder in a short period of time, so don't run it this way for any longer that it takes to quickly test out an adjustment. For this reason re-jetting is best done in small increments rather than large ones.

The slide needle clip adjustment has served you well for anything lower than 3/4 throttle.
If you still are not sure what 4-stroking is, here is an excellent utube video on the subject that I like to share as a teaching tool. No, it is not my video. I just stumbled across it and it is a good one.
http://www.youtube.com/watch?v=0wzph3hL6EE

 

[2door]

I agree with Gearnut's assertion regarding plug color with Syn oils. I run Opti-2 @100:1 and all my plugs are grey, not tan or brown. The shade of grey is what I look at when tuning/jetting. Lighter means lean and darker equals a richer mix. I usually shoot for something like a battleship tone


As always the rest of his advice is right on so stick with his help and good luck. Let us know how things go. Oh, and by the way. It appears that you are at or near sea level, less that 100' above.

Tom

 

[Felix]

ok so i moved the needle clip down a notch to the second position from top. I used my bike to work these past to afternoons ( dont take in morning cause i have no cup holder for coffee mug lol). Its 3 miles round trip, so 6 miles later this is how the pulg looks now.

u can see where i said it had like a "wet" look.

 

[2door]

To get an accurate spark plug reading you'll need to do a 'plug chop'.

Run the bike at wide open throttle for at least twenty to thirty seconds then hit the kill switch, pull the clutch and let the bike coast to a stop. We always recommend that you allow the engine to cool for a few minutes before pulling the plug. This is to prevent you from possible stripping threads due to the difference in expansion and contraction between the steel plug and the aluminum cylinder head.

The wide open throttle with an instant kill is the best way to read plug color. If it is allowed to idle or run slow before shutting down you won't get a true reading.
Ride it hard then shut it down.

Tom

 

[Felix]

To get an accurate spark plug reading you'll need to do a 'plug chop'.

Run the bike at wide open throttle for at least twenty to thirty seconds then hit the kill switch, pull the clutch and let the bike coast to a stop. We always recommend that you allow the engine to cool for a few minutes before pulling the plug. This is to prevent you from possible stripping threads due to the difference in expansion and contraction between the steel plug and the aluminum cylinder head.

The wide open throttle with an instant kill is the best way to read plug color. If it is allowed to idle or run slow before shutting down you won't get a true reading.
Ride it hard then shut it down.

Tom

Ok great thanks for letting me know, I'll try that out tomorrow and then post pics.

 

[heyscuba]

How many miles would you say is on the plug in your photo? The color of the porcelain appears to be on the light side telling me you are running a tad lean. Preferably you'll want that plug to be more of a chocolate brown color as opposed to white or grey. The lighter the color the leaner the fuel to air mix.

My guess is you need a little larger jet size. I don't go by jet numbers. My experience is they are nebulous at best. I solder and re-drill and experiment until I get the performance I want.

If you give me a city, or the name of the closest airport, I'll tell you your elevation. That plays heavily into tuning for best performance.

Tom

I am reading the thread and getting a lot of good, fuel mixture and spark plug info from you guys,...!!!

 

[GearNut]

I am glad to be of help, heyscuba.
Ride safe!

 

[movinfast]

i have a real dilema. my plug looks grey so i would think it is lean, but it sounds just like the four stroking video at the top end. the mid range runs great, and if i throttle it like a weed eater i get good power. im worried that im running lean because of the grey plug and it is hot as **** after a few mile ride and it is october. if it is a good mix in the mid range would it still be grey when u do the chop. and does the starving engine sound like 4-stroking. i have a pocket bike exspansion chamber but head pipe is a little long so i dont know if that is distorting the sound. plz help

 

[GearNut]

Simply having a grey colored spark plug does not mean that the carb is tuned too lean or too rich. It only means that the spark plug took on the color as deposited at the RPM that you last ran the engine at.
This included any and all idling, low RPM's through high RPM's as well. It would be a "muddied: or "mixed" chop. No good for a tuning aid.

Performing a plug chop properly colors the spark plug at the particular RPM that you are having issues at.
If you are having high RPM issues, do a high RPM chop.
If you are having mid-range RPM issues, do a mid-range RPM chop.
I think you get the idea.
Never, ever under any circumstances, let the engine run at a different speed other than the speed at which you are having tuning issues with.
Run the engine at the particular speed for a few minutes, 1/2 mile or so.
After that time, distance has been covered you MUST pull in the clutch and hold down the kill button at the same time. Let the engine die without running under it's own power at all and come to a stop.
Coast the bike or pedal it to wherever you are going to do the spark plug removal.
Do not let the engine turn over if you can help it. Keep the clutch lever pulled in and the rear wheel disconnected from the engine the whole time.

After you arrive at your destination let the engine cool down about 1/2 hour. The cylinder head should feel barely warm to the touch. If you try to remove the spark plug when the engine is hot you run a very good chance of removing the threads out of the cylinder head along with the spark plug. Not good, not cheap to repair unless you enjoy buying new cylinder heads regularly.

4-stroking happens when the state of carburetor tune is adding too much fuel to the incoming intake air charge. It is too rich.

It is very possible to run rich at low RPM's good at medium RPM's and lean at high RPM's.
I mean is it possible, not that it is good.
You can also run a mix of that too. Lean at low RPM's, ok at mid RPM's and rich as he11 at high RPM's. It all depends on how the carburetor is tuned.
Not good either.

A lean, fuel starving engine at high RPM's sounds healthy and strong. It also could ping, or have pre-ignition, and the power can fall off even though the RPM's are still increasing faster. Also it could have a lurching feel to it when holding a steady throttle. position.

 

[movinfast]

ok so all the chops i have done are at high rpm's. the plug continues to look grey. my dilema is that the plug definatly looks as if im running lean, but sounds just like the 4-stroking video. so i wonder if it is pinning or detenating as it seem hotter than it should be. i opend the jet to .028 i had more power but still sounded like the 4-stroking just not as bad. i have jetting drills coming and i think i will make a video so everyone can way in. it is also interestin that it act just like the hesatating or bogging so often mentioned on this site

 

[GearNut]

movinfast, have you tried a new spark plug?
You might not have a major carburetor tuning issue at all.
A bad spark plug can run good at low RPM's but misfire at high RPM's.
Also any loose or poor electrical connections between the engine and CDI box can cause misfiring at any RPM, especially high RPM's when the vibration is greatest.
The same goes for the where the spark plug wire attaches to the spark plug cap and sometimes how well the spark plug cap clips onto the spark plug terminal.
It also could be the kill button on the handlebars. It will be vibrating and shaking all around internally (and with the poor quality that they are notorious for having) and causing erratic self engagement.

 

[movinfast]

my bike is running better with the larger jetting, but u raise a good point. the plug now has a more chocolate look, though i would like it a little darker. but i have noticed that when taking out the plug the cap on the plug is unscrewing. when i take off the wire i retighten the cap. im also runing a ngk #6 plug so i think im gana switch to a #7. maybe it will help with the excecive heat.

 

[GearNut]

The heat range of the spark plug has nothing to do with the operating temperature of the engine, only the operating temperature of the spark plug itself. It needs to be hot enough to be self cleaning but not so hot as to blister the ceramic or cause pre-ignition.
Here is a link to a brief but good read about it all: http://www.dansmc.com/sparkplugs1.htm