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soulsedg3

Spark Plug pic (opinions?)

20 posts in this topic

Just need some opinions on how this plug looks to you all.   It's out of a 2003 yz 450.    The plug was pulled before i just got it running again, so the results of this are from the previous ride (30mins) before i noticed i lost a water pump seal.   It was run thru the full range.     But was backfiring a bit on a completely shut off throttle.    i'd say this was too lean if i was going off what my old 2 strokes used to look like.  this is my first 4 stroke, so i'm a bit clueless.

 

does this seem to be burning ok?  (two pics)

 

plugreduced1_zps37d51017.jpg

 

 

 

 

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plugreduced2_zpsfc3f09df.jpg

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You cannot determine anything about fuel mixture by reading plugs when you're using unleaded fuel.  No lead, no color.

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on a side note.   it is a COMPLETE pain in the ass pulling the plug, short of taking the fuel tank partly off.  

 

at this point i'm almost wishing i had gone 2 stroke. lol.

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You cannot determine anything about fuel mixture by reading plugs when you're using unleaded fuel.  No lead, no color.

 

this same concept doesnt apply to all things running unleaded, correct? when you mix the fuel, does this still ring true?

 

i know some mechanics in cars, can tell you if your running rich/lean and even running proper timing, just from looking at plugs.

 

i could pinpoint exactly how my old kx 125 2stroke was running just by quickly looking at the plug.  

 

....regardless i appreciate the posts guys/gals =)

Edited by soulsedg3

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Today's fuels do not read well on a plug.  If it is black it is way too rich and will run that way.  Anything nearing a good mixture will look much like what you have.

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IMO it's safe to say by the looks of that plug and the conditions your describing that your bike is running lean. Does it have any performance mods? Are the jets stock?

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after only 20 minutes its hard to tell anything, bike will surge if to lean.Not like a 2-stoke it will not hurt it. What did you change to make you worried? And they do backfire to.

Edited by mdsharon

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Hey guys. Nothing particular madr me worry. The only thing was the backfiring. It was quite excessive after i put all new exhaust gaskets in and limped home with antifreeze pissing out of the seal bypass hole.

I guess im just stuck in my old teo stroke thinking. A plug looking like this was baddddd.

put plug back in....put it all back together. New seals..new impeller shaft. New bearing for shaft...started it last night. Cranked fuel screw out another turn. Let it warm up...went up my road at 8pm(sure my neighbors love me). Backfiring all but disappeared except on excessive decel where it was doing it only a tiny bit.

Im out 3 1/2 turns now. So guessing i need a larger pilot jet.

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Out of my '08 450 back in April 2009.  Stock excepting a PMB end cap spark arrestor. Bike was new with about 30hrs.  This was after a 3+/- hour desert race at varying speeds.  I've been told it doesn't mean anything but I'm stuck in the 2 stroke days too because I was glad to see this color.

FWIW: Outside temp was between 50 and 60 deg F,  Altitude around 5000'.  160 Main, Needle Clip at 3. 2 turns out on the fuel screw.

2009_0430_052037AA.JPG

2009_0430_052004AA.JPG

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That plug color was developed by riding for a period of time under the entire range of throttle and load conditions, wasn't it?  Then it cannot be any kind of accurate gauge of any of your jetting at all.  It does indicate that the bike is generally running well, isn't burning significant amounts of oil, isn't detonating, and the plug is the right heat range, though.

 

The only way to read jetting on a plug is to run under full throttle, chop the throttle at the end of the run and kill the engine while you stop the bike, then remove the plug and read it.  Anything else, you're just kidding yourself.  If you do that with the plug you have there on unleaded gas, it will be bone white.

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Out of my '08 450 back in April 2009. Stock excepting a PMB end cap spark arrestor. Bike was new with about 30hrs. This was after a 3+/- hour desert race at varying speeds. I've been told it doesn't mean anything but I'm stuck in the 2 stroke days too because I was glad to see this color.

FWIW: Outside temp was between 50 and 60 deg F, Altitude around 5000'. 160 Main, Needle Clip at 3. 2 turns out on the fuel screw.

This is what i was expecting to see also.

This is all good info....so gray if i ride the full range of my bike....on supreme gas i might be able to get something like above? After say a 2 hr ride.

Thanks guys/gals. Im positive my bike is a bit lean down low. Runs great thru the whole range. Very little backfiring now....only when chopping throttle....and its a lot less then it was.

BUT....when the bike is warm....to get it to start i have to twist throttle a tiny little bit as i kick it over. If i dont.....it is a bit of a pain in the ass to start. If i twist a lil. Starts first kick at warm.

Hence why i think its a lil lean down low still.

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This is what i was expecting to see also.

This is all good info....so gray if i ride the full range of my bike....on supreme gas i might be able to get something like above? After say a 2 hr ride.

Thanks guys/gals. Im positive my bike is a bit lean down low. Runs great thru the whole range. Very little backfiring now....only when chopping throttle....and its a lot less then it was.

BUT....when the bike is warm....to get it to start i have to twist throttle a tiny little bit as i kick it over. If i dont.....it is a bit of a pain in the ass to start. If i twist a lil. Starts first kick at warm.

Hence why i think its a lil lean down low still.

Maybe need to adjust the valves,If mine starts to get tight on the intake I would have to crack throttle a bit, when adjusted right takes half kick, starts super easy!

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on a side note.   it is a COMPLETE pain in the ass pulling the plug, short of taking the fuel tank partly off.  

 

at this point i'm almost wishing i had gone 2 stroke. lol.

you don't have to pull spark plugs out as much on a 4-stroke...i took mine out and it was all rusted to crap..guess it was too rich :p still learning :) I just bought a new one to save myself the hassle for when it does foul out. plus it's better to run new than used IMO.

 

10818978_10100213339957369_1080396339_n.

 

I bought the bike with 12hrs it's a 2009 WR250f...i probably put double that...and that's what happened...we'll see how the new one hold up :p

 

 

oh yeh and i know it's not a pic of the top of the spark plug but i was taking pics to make sure i got the right plug from the store :p which the numbers i needed were on the other side and i got a pic of those too! :p haha just a random thought before you laugh at that

Edited by mL480

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...so gray if i ride the full range of my bike....on supreme gas i might be able to get something like above? After say a 2 hr ride.

Thanks guys/gals. Im positive my bike is a bit lean down low. Runs great thru the whole range. Very little backfiring now....only when chopping throttle....and its a lot less then it was.

BUT....when the bike is warm....to get it to start i have to twist throttle a tiny little bit as i kick it over. If i dont.....it is a bit of a pain in the ass to start. If i twist a lil. Starts first kick at warm.

Hence why i think its a lil lean down low still.

 

It may take several hours for the plug to develop that much color if the plug's new and the bike really runs right.  But yes, that plug looks like you want one to.

 

A properly tuned YZ450F with a carb should pop out the exhaust on decel, most of the time, a little bit. Subjective terms, yes, but that's reality.  My '03 was exactly like that; you often had to crack the throttle open just slightly to get it to light up, but that means it's slightly rich, not lean.  Opening the throttle adds nothing but air until the air flowing through the carb rises far enough to get the main circuit to work. 

 

Don't make the idle too fat.  The bike will develop bad behaviors.

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Does it backfire under acceleration or when you let off like rolling into a corner?

If it's when you let off, have you checked the exhaust header gasket? My bike eats through them and when it's due a change it sounds like Thor's hammer.

Backfires are tiny little pops on decel. Occassional get a bigger one. Kinda like what gray said. Its so little its not concerning to me. It was a lot worse. Then i replaced both exhaust gaskets and did a carb rebuild. The guy that did my carb wired up something he said. Gives it more response...something like that.

The thing pulls like a train when you whack the throttle. Smooth steady and ferocious. Not quite as much midrange as my buddies 08 kawi 450....but damn close.

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It may take several hours for the plug to develop that much color if the plug's new and the bike really runs right. But yes, that plug looks like you want one to.

A properly tuned YZ450F with a carb should pop out the exhaust on decel, most of the time, a little bit. Subjective terms, yes, but that's reality. My '03 was exactly like that; you often had to crack the throttle open just slightly to get it to light up, but that means it's slightly rich, not lean. Opening the throttle adds nothing but air until the air flowing through the carb rises far enough to get the main circuit to work.

Don't make the idle too fat. The bike will develop bad behaviors.

Thanks gray. Good to hear about the throttle to start on kicking :)

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