06 yz450 Spark Plug burning white after 48pilot/170main


24 replies to this topic
  • SurvivorMan

Posted April 04, 2006 - 10:45 AM

#1

Yikes!! I pulled my plug out a day ago and it was no where near tan....it was white as I have ever seen a plug.
My elevation is between 4000-5000 ft, and it's farely dry.
Temp- 40-50
The rest of the bike is stock: exhaust, air box, and all other jets besides the 170 main and 48 pilot.
With my elevation, temp and humidity I should want a leaner setup then the cali, texas guys, so it makes me wonder how lean your bikes are running.
I think i'm going to go richer on pilot 50 or 52, main 175, leak 60. just keep messing around!? oh yeah, I'm also going to get a richer needle.
Any other suggestions?

  • PK

Posted April 04, 2006 - 10:51 AM

#2

What kind of gas are you running? That's pretty unusual, especially considering your altitude. How did you check the plug? How does the bike run & start when it's cold and hot? Have you played with the fuel screw? If the pilot was too lean you would get a popping on deceleration with the throttle closed and if the main was too lean you would get some hesitation/sputtering with the throttle wide open at a high rpm when riding. Do you get any of these? Do you need the choke to start the bike when it's cold? I'm not doubting what you saw, but why would your bike be reacting so much differently than 99% of the others? Weird...

  • MotoGoalie

Posted April 04, 2006 - 10:54 AM

#3

Yikes!! I pulled my plug out a day ago and it was no where near tan....it was white as I have ever seen a plug.
My elevation is between 4000-5000 ft, and it's farely dry.
Temp- 40-50
The rest of the bike is stock: exhaust, air box, and all other jets besides the 170 main and 48 pilot.
With my elevation, temp and humidity I should want a leaner setup then the cali, texas guys, so it makes me wonder how lean your bikes are running.
I think i'm going to go richer on pilot 50 or 52, main 175, leak 60. just keep messing around!? oh yeah, I'm also going to get a richer needle.
Any other suggestions?


That's pretty zany.

Granted, I'm riding an older bike but essentially a similar model and I ride in the same altitude and weather. I have a PJ of 38 and MJ of 155. :thumbsup:

My plug is black and the bike runs perfectly. :thumbsup:

And theres' a whole bunch of us that have similar jetting along those lines.

  • CRFThumper

Posted April 04, 2006 - 10:57 AM

#4

What kind of gas are you running? That's pretty unusual, especially considering your altitude. How did you check the plug? How does the bike run & start when it's cold and hot? Have you played with the fuel screw? If the pilot was too lean you would get a popping on deceleration with the throttle closed and if the main was too lean you would get some hesitation/sputtering with the throttle wide open at a high rpm when riding. Do you get any of these? Do you need the choke to start the bike when it's cold? I'm not doubting what you saw, but why would your bike be reacting so much differently than 99% of the others? Weird...



There could be a 100 answers to that!Jetting most likely but what about air leaks,timing and a lot of others.On my 06 all I did was bump the pilot up and it's great but others have not been so lucky!

  • falk781

Posted April 04, 2006 - 11:55 AM

#5

I was checking the valves on my 06 450 the other day and I took the plug out to find nearly the same thing.

There was just a hint of tan, no where near the cardboard color it should be.

I'm running a 48 pilot and the stock main. I intend to put the 170 in it this weekend to try it out.

No starting problems or drivability.

The only thing I notice is very slow riding at the point where the pilot leaves go and the needle picks up is slightly sloppy. THis of course is at practically 0-1/16 throttle.

Under hard acceleration it's right on.

  • SureBlue

Posted April 04, 2006 - 07:28 PM

#6

I was checking the valves on my 06 450 the other day and I took the plug out to find nearly the same thing.

There was just a hint of tan, no where near the cardboard color it should be.

I'm running a 48 pilot and the stock main. I intend to put the 170 in it this weekend to try it out.

No starting problems or drivability.

The only thing I notice is very slow riding at the point where the pilot leaves go and the needle picks up is slightly sloppy. THis of course is at practically 0-1/16 throttle.

Under hard acceleration it's right on.


If you richen the pilot and main (like you in most cases need to for this bike),
you also need to richen the needle. What makes anybody think the bike is lean only in pilot circuit or WOT, but not in the midthrottle? Do people suggest the stock jetting is somehow out of balance and only needs partially richened?
It should be clear for every sunday do-it-yourself jetting expert to rejet thru the whole range. So with a 48 pilot and 170 main, lower the clip one notch to get the needle up one. Then the balance remains and there are no hiccups. In some cases moving the clip is not sufficient and you need another needle due to different tapers and diameters. Like jets, there are several different needles. You just need to find out what the correct setup is for your temps, altitude and humidity, baselines can be given, but it actually and unfortunately is only a matter of testing; trial and error. Most of us neglect the necessity to also do something to the needle. :confused:
BTW - it is also all in the manual, pages 7-5, 7-6 and 7-7.
I'm no jetting expert but I'm sure Burned can more or less verify this.
Stay in balance with your jetting. :thumbsup: :thumbsup:

  • SurvivorMan

Posted April 04, 2006 - 09:23 PM

#7

The bike runs much better than stock. The 48 pilot cured the popping on decel and WOT feels pretty crisp. Not really any burbles or hesitations except for at idle, then crack the throttle quickly...the bike then breathes heavy. But i believe this to be a leak jet situation, which is described in the manual in section 7. i will be ordering a #50 and a #45 leak to richen(why would the leaks in a smaller number be richer when every other jet is leaner with a smaller number??)
But overal the bike runs good...90%...The only time i can get it to pop now on decel is if I am wheelieing down a road...so WOT for a while, but that is very rare. the bike starts well, not the absolute best, but usually first or second kick. It helps to blip the throttle slightly at the bottom of the kick stroke and the bike starts first kick every time weather it is in gear, hot, cold, always seams to work.
I doubt an air leak or timing because the bike runs near perfect, that is why i was so shocked at the white plug. Seams to run pretty much perfect except for the odd time right off bogging it down low then a quick blip like a 2 stroke.
I ordered a richer needle, getting info from the manual in section 7 was helpful, for now I will raise the needle 2 clips and see if this helps.
It is very strange though that nobody else has a white plug?! especially that I am at a high altitude

  • SureBlue

Posted April 05, 2006 - 02:40 AM

#8

Please then report what the leak jets did, I'm curious to hear.
I have not checked my plug yet, but will soon do it as I want to install the Iridium plug.

  • SurvivorMan

Posted April 05, 2006 - 09:55 AM

#9

I figured out why I need a smaller leak jet to get a richer AP squirt...these forums have been really detailed and helpful!! i found the write up at thumperfaq.com, i will have to find the link. i will ride it tonight with a 175 main and 2 clips down on the needle and then check the plug and report back. has anyone else checked their plugs and found white?

  • SureBlue

Posted April 05, 2006 - 10:21 AM

#10

I ran 48-175-1 clip down stock needle, fuel screw 1,75-2 out this winter, sea level at. max -10 Celsius an it ran fine. I could have tried 50 pilot and 2 clips down, but did not want to do dramatic changes at once. I wanted fatter top to ensure enough fuel when riding on ice or on deep snow which loads the engine at WOT.
I would first try only one clip down and perhaps a bit smaller than 175 main. You don't want to loose the crispines with too fat jetting. Remember your altitude 4-5K ft. speaks for leaner jetting than mine.
I'll check the plug tomorrow and post a pic if I have time. Not that it helps you much but I'm curious too. Similar bikes and riding conditions can anyway result in different optimal jetting, it is individual and only guidelining what others use.

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  • MotoGoalie

Posted April 05, 2006 - 11:07 AM

#11

Something just doesn't add up here. How can he be running Sea Level jetting at high altitude and getting a 'lean' reading plug?

What kind of fuel are you running dude?

  • Eddie Sisneros

Posted April 05, 2006 - 11:33 AM

#12

its the fuel that makes them look that way.it isnt any real indication of jetting regardless of what you read.

they will look like that when jetted properly.

  • grayracer513

Posted April 05, 2006 - 01:41 PM

#13

Specifically, it's the lack of lead in the fuel that has the most to do with it. Plugs have been very hard to read since the lead was removed.

  • bigred455

Posted April 05, 2006 - 04:10 PM

#14

Once again,you are wasting your time jetting by looking at the porcelin of the plug.You will be chasing your tail all day and ruin the washer on the plug. Forget about looking at the plug,move those jets and trust the reaction of the motor.Your new white plugs are telling you that you have the correct heat range. A lean looking plug is not going to be white like you are seeing,it is a totally different white(glazy).STOP IT WITH THE PLUGS!!!!!!!! :thumbsup:

  • Fastest1

Posted April 05, 2006 - 05:12 PM

#15

Once again,you are wasting your time jetting by looking at the porcelin of the plug.You will be chasing your tail all day and ruin the washer on the plug. Forget about looking at the plug,move those jets and trust the reaction of the motor.Your new white plugs are telling you that you have the correct heat range. A lean looking plug is not going to be white like you are seeing,it is a totally different white(glazy).STOP IT WITH THE PLUGS!!!!!!!! :thumbsup:

A correctly taken plug chop is STILL an indispensable tool. Though I do believe he is chasing a different gremlin. Something else is going on or he isnt reading the plug correctly. To make sure you dont have an air leak, spray WD40 around the boots while running, if the rpms change at all, there is a leak.

  • Fastest1

Posted April 05, 2006 - 05:18 PM

#16

If you richen the pilot and main (like you in most cases need to for this bike),
you also need to richen the needle. What makes anybody think the bike is lean only in pilot circuit or WOT, but not in the midthrottle? Do people suggest the stock jetting is somehow out of balance and only needs partially richened?
It should be clear for every sunday do-it-yourself jetting expert to rejet thru the whole range. So with a 48 pilot and 170 main, lower the clip one notch to get the needle up one. Then the balance remains and there are no hiccups. In some cases moving the clip is not sufficient and you need another needle due to different tapers and diameters. Like jets, there are several different needles. You just need to find out what the correct setup is for your temps, altitude and humidity, baselines can be given, but it actually and unfortunately is only a matter of testing; trial and error. Most of us neglect the necessity to also do something to the needle. :confused:
BTW - it is also all in the manual, pages 7-5, 7-6 and 7-7.
I'm no jetting expert but I'm sure Burned can more or less verify this.
Stay in balance with your jetting. :thumbsup: :thumbsup:


Actually this is not entirely true. Lets say you adjust the fuel screw richer the overlap causes the mixture throughout the rpm range to be richer not just at idle. The orifice size is increased allowing more fuel at all throttle openings. Adjusting more than one parameter at a time is a headache without a lot of experience. All circuits affect each other.

  • Eddie Sisneros

Posted April 05, 2006 - 05:21 PM

#17

leave the plug in the motor.you could do plug chops all day long and still be way off.

if you really want to open your eyes to jetting,get a wideband a/f meter.

besides the one i use on my dyno i use a dynojet wideband commander on the bikes during development track testing.its data logs and you can down load the readings.

  • bigred455

Posted April 05, 2006 - 06:08 PM

#18

A correctly taken plug chop is STILL an indispensable tool. Though I do believe he is chasing a different gremlin. Something else is going on or he isnt reading the plug correctly. To make sure you dont have an air leak, spray WD40 around the boots while running, if the rpms change at all, there is a leak.


A plug chop will get you nowhere quick. It takes quite sometime to gain color on a new plug.You can be running rich and know it,but the plug will show white. I have done alot of plug testing in the past,I have learned to trust what the motor likes. Plug chops are worthless!

  • SurvivorMan

Posted April 06, 2006 - 06:33 AM

#19

Thanks, that makes it easier to understand. I am so used to a 2 stroke. I will leave the plug alone. the bike has been running awesome; crispy and responsive, even the quick crack of the throttle at the bottom is vertually non exsistent.
One thought, I installed tall bars which also raises the hot start. after doing my valve inspection last night (after 30 hours on the bike, all 5 valves are within spec!! awesome!!) i noticed the hot start cablt to be very tight and moves slightly when I move the bars. i know when the hot start lever is pulled it leans out the carb, but my bike runs great, it idles the same in all circumstances and responds the same in different corners. i guess i just freaked myself out for no reason.
I will leave the 175 main in just to feel the results, if too rich easy to pull.
still waiting on the #50 and #45 leak jets

  • SurvivorMan

Posted April 06, 2006 - 06:42 AM

#20

Burned, what is a wideband a/f meter and can i purchase one at a decent price? something to meter jetting through the tail pipe i'm assuming? this would be a handy instrument to own if it's simple to use (without a dyno!!)





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