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Check out my spark plug! Pics inside.

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Installed this NGK Br8eg 4 or 5 rides back. This bike is currently jetted exactly as to what my service manual calls for for these temps except the air screw is only 1 turn out when it needs to be @ 2, but I have had a bit of a surge the last couple rides, so I'm thinking I need to bump up my pilot 1 size richer for sure. The bike runs perfect other than the surge it gets sometimes, but it's not too terrible.

Anyway, this is not after a plug chop or anything but just how my plug looks in general. Tell me what yall think! This is my first time doing a plug reading. I promise I won't post them everytime lol but I'm hoping that light brown on the tip is the "mocha brown" everyone says it should be!

IMAG0538.jpg

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looks almost perfect! maybe a tad lean...but leaner is meaner lol

How can you tell without looking down into the insulator base? IMO it's a very nice burn but if I was picking I would say the richer side of perfect. I would expect darker the further down, I only say this because Ive read that the insulator at the electrode can burn almost white but its at the base of the insulator it should be measured, BUT with all that said - Im too chicken to attempt that, I burn mine like the pic

Edited by gitenold

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Oh man that is great news. I've been having a lean surge coming off the power and when idling and when I blip the throttle it will go away and then come back, but whenever I'm on the power it's like butter. I know my main jet is good and likely my power jet as their both set to factory specs, but my pilot I fear is a little lean because the air screw is telling me so, along with the surging.

I guess I just wanted to make sure it looked okay, but this was NOT a plug chop. This is just me throwing the plug in and going riding 4 or 5 times! I guess I can rest a little assured it's not dangerously lean by looking at the plug this way!

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plug readings are hard to do with all the gas additives and ethanol and crap in the fuel now

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How can you tell without looking down into the insulator base? IMO it's a very nice burn but if I was picking I would say the richer side of perfect. I would expect darker the further down, I only say this because Ive read that the insulator at the electrode can burn almost white but its at the base of the insulator it should be measured, BUT with all that said - Im too chicken to attempt that, I burn mine like the pic

I say a tad lean because the color of the plug looks pretty light atleast on my screen not to mention dry...not saying I wouldn't run it that way...if it looks like that and runs good let her rip!

true though you should be looking deeper inside the plug for the color and they usually are darker towards the base. good point!

IMO...best test is with a fresh plug and throttle chop after a hard pass through the gears....but there are also many opinions on the "best" way to tune the carb/plug...

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I did some more searching and found this chart, Looking just at the base of the threads I would say it leans on the rich side.

jetting.jpg

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That picture is very interesting but I don't see anything about the color of the base of the threads. According to that chart my plug tip is saying the plug is too cold right? Anything else anyone else gather.

Someone else said my plug "leans on the rich side" that confused the hell out of me lol. I am about to put a richer pilot in it and correct the air screw, like I said, but other than that this carb is right where it's supposed to be, service manual wise.

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That picture is very interesting but I don't see anything about the color of the base of the threads. According to that chart my plug tip is saying the plug is too cold right? Anything else anyone else gather.

Someone else said my plug "leans on the rich side" that confused the hell out of me lol. I am about to put a richer pilot in it and correct the air screw, like I said, but other than that this carb is right where it's supposed to be, service manual wise.

I should have just said "Flat surface" it says "Jetting Read flat surface - brown is perfect"

Don't get me wrong, I would be satisfied with that plug because I jet for woods. I would be confident to blast down some fire roads or get on a track without worrying about running too lean.

Why change out the Pilot? are you at the a/s limits?

Use the plug your owners manual calls for and just jet for the way you ride - I think your plug looks good to me, Im just say n IMO you have some room before you go too lean

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I should have just said "Flat surface" it says "Jetting Read flat surface - brown is perfect"

Don't get me wrong, I would be satisfied with that plug because I jet for woods. I would be confident to blast down some fire roads or get on a track without worrying about running too lean.

Why change out the Pilot? are you at the a/s limits?

Use the plug your owners manual calls for and just jet for the way you ride - I think your plug looks good to me, Im just say n IMO you have some room before you go too lean

Yeah I know that's how it looks and it confuses me because I am at the limit on the air screw. Currently at 1 turn out, I could go to 2 turns out (service manual recommended) but I also have a surge going on at idle or upon slowing down that I can only attribute to a "lean surge" any other reasons it could be doing that?

But yea I want to bump the pilot up 1 to get the air screw back out to 2 turns...but couldn't I just raise the needle clip and that would richen it up enough more for me to pull the air screw back out a turn?

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Clean Air filter

Float level set

No air leaks

Throttle cable routing?

If all this is good then your on the right track with the a/s and pilot

Read this and it will tell you how the 3 circuits influence each other and how to setup the jetting. Sounds like your just about there

http://justkdx.dirtrider.net/printcarbtuning.html

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Okay cool I was told bumping up the needle clip would help richen up the pilot but I think that's some BS. I need to just order a new Pilot from Motosport or somewhere.

-Air filter stays clean always

-Brand new motion pro throttle tube, housing, and cable, and I made sure it was routed correctly.

-AIR LEAK I AM IFFY ON

Because recently (and I have a whole thread about this) I was riding at the track and came up a slight hill, did a little power wheelie. The throttle went to wide the Fuuu open on me. Bike did a back flip and ripped the rear fender in two without hesitation and then landed still in full throttle. Highest RPM possible on a 250 2 stroke that at the time I did not have a kill switch installed on.

This same thing had happened once to me before when I started the bike up. The first time we chalked it up to the slide sticking somehow, but honestly after it all happened I noticed that it still had the same throttle tube/cable/housing on it from 5 years ago when I owned it and I had the bike for 2 years so that's at LEAST 7 year old throttle package on the bike. Not only that, but the cable was routed wrong before we put all the new stuff on (when it went full throttle both times)

Now that I've had the new stuff on and routed right it hasn't done it what so ever, but my point was in the thread that I made about it at first everyone said it's your cable tube, etc etc but then everyone basically started saying I had an air leak, except most of them that were SURE I had an air leak weren't even reading the information I was providing them, so I took it with a grain of salt.

So far we have ran the bike while spraying all exterior surfaces with carb cleaner along with taking the stator cover off and spraying it in there. The bike did not rev up or change throttle at all, so NO exterior air leaks.

I am putting a Wiseco top end in the bike over the next few weeks and so I plan on doing a leak down test before hand to make sure there are no air leaks, but as far as the bike going to full RPM I believe that was just decade old throttle tube/housing/cable routed incorrectly, because it was NASTY dirty. All of it. Also it only stuck randomly those 2 times. So far so good. I am hoping there are no internal air leaks, we will see, but for now I plan on bumping up the pilot just 1 size from 55 to 58 and hopefully that will do it.

Besides, if it was an air leak I would think the bike would rage @ full rpm more often and I also would think I'd have to heavily go rich on all of the jets. Where as right now I'm exactly where I'm supposed to be according to the manual and the plug, besides the pilot/air screw/surging so hopefully it is just that. I've been told every bike is different and I'm sure most people have to go a little off of what the exact jet specs are for the manual sometimes. Especially in winter when it goes lean and you need to richen it up!

Sorry for the novel but that's my story for now! I'm glad my plug didn't come out white! Then I'd really be worried, but the bike really runs good except when warmed up it has that surge and I've GOT to get that straightened out before the new piston goes in. Thanks for looking and let me know if you have any other thoughts on my info above!

Griffin

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plug readings are hard to do with all the gas additives and ethanol and crap in the fuel now
I'm glad my plug didn't come out white!

Listen to MegaDeTH.

My plugs come out pretty darn white. But I can assure you I'm a tad rich (I don't want to swap brass just to hit the local sand track).

With the fuels we get from the pump nowadays they muddy up the plugs color quite a bit. The only way I would jet a 2t is by feel and sound. Then verify by inspecting piston wash, deposits, burn marks, etc.

But from looking at your plug, you're rich. Couldn't tell you on which circuit, but again you can't jet a circuit off a plug that has multiple hours on it.

If it's surging on idle after throttle chops, take in your airscrew or get a bigger pilot.

If you're running race gas or a mixture of race and pump gas, then disregard what I said above.

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honestly when i choke my bike b4 i start it the motor will go wide open and go tell theres no more. I have no air leaks, bikes are just different. Put a new jet in but just go to any moto shop an they should have jetts for ur carb instead of waiting. Adjust ur needle screw as needed i would talk all info with a grain of salt start where ur bike runs good then adjust carb acording to throttle position.

0 to 1/4 throttle- pilot jet

1/4 to 1/2 throttle- neddle (note= needle and main jet overlap)

1/2 to wide open- main jet

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Listen to MegaDeTH.

My plugs come out pretty darn white. But I can assure you I'm a tad rich (I don't want to swap brass just to hit the local sand track).

With the fuels we get from the pump nowadays they muddy up the plugs color quite a bit. The only way I would jet a 2t is by feel and sound. Then verify by inspecting piston wash, deposits, burn marks, etc.

But from looking at your plug, you're rich. Couldn't tell you on which circuit, but again you can't jet a circuit off a plug that has multiple hours on it.

If it's surging on idle after throttle chops, take in your airscrew or get a bigger pilot.

If you're running race gas or a mixture of race and pump gas, then disregard what I said above.

I would like to see a pic of you plug, and disregard what part if mixing race or running race?

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I would like to see a pic of you plug, and disregard what part if mixing race or running race?

Disregard the parts about reading plugs with pump gas. The part about surging is applicable to any gas.

Here's a pic of my plug. It probably has around 15-20 hours on it. Br8iex

Also a picture of my piston with 40 hours, which will shows I'm a little rich.

EDIT: I wouldn't try to jet any bike to match the plug I have. Many different factors can change the color of your plug. If your plug does in fact come out as white as mine, I would inspect the top end to insure you're safe, unless you have enough seat time to feel rich/lean and detonation.

2011-11-23193228.jpg

2011-11-23192819.jpg

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Idle set too high will cause a lean surge at idle or upon decel with a completely closed throttle.

Okay very good because my 2t will idle on it's own! But the thing is I want it to be able to idle. I like it that way. The only thing is on the 98's the idle adjuster is actually the choke knob itself. Clockwise for idle up and visa versa, but it's very unresponsive. I can screw the hell out of it either way and it feels like it's barely working.

I feel like I really need to investigate this choke knob and make sure it's working properly, but the idle does change when turning it, but just not very consistent on how it does it!! I feel like that could DEFINITELY be causing my lean surge!

As far as the whole plug color I am officially confused now. We never set my idle and air screw at the same time, which is what I read about in the manual. We need to do that and then see where she's at! Bet it goes away. Still gonna buy a 58 pilot jet though.

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