Jump to content
Sign in to follow this  

Plug color read .....

Recommended Posts

 I got a 03 WR250F. Changed the oil, coolant. It already had the airfilter snorkel out, Grey wire and throttle mod. I opened the plug and saw its quite black. I am thinking the jets need to be changed. I dont really know how to read plugs that well so I will put them on here for someone more experienced to read them. What do you think ?

 

The bike starts fine, runs ok. I really dont know about the jets in it. Havent done the carbs yet. I will be riding around 1000~2000 ft

20130910_145629.jpg

Share this post


Link to post
Share on other sites

You look a little rich but as long as its dry soot I would try to lean out the file air screw a little bit and you should be fine. You kind of want a cardboard color to be perfect.

Share this post


Link to post
Share on other sites

You cannot jet based on  plug color with todays additive rich fuels. All that matters is how the bike runs, Only address actual individual diagnosed issues, if any.

Share this post


Link to post
Share on other sites

i will lean out the air screw and then see thanks.

Share this post


Link to post
Share on other sites

You cannot jet based on plug color with todays additive rich fuels. All that matters is how the bike runs, Only address actual individual diagnosed issues, if any.

you can get pretty close.

Share this post


Link to post
Share on other sites

you can get pretty close.

No, you cannot. The plug will be black or white. No shades inbetween. A plug will tell you if you have serious fouling issues but that should be very apparent well before even removing the plug.

If you run race fuels, some are relatively pure and you will be able to read the plug however, those that want to accurately jet a bike use a wideband.

Share this post


Link to post
Share on other sites

No, you cannot. The plug will be black or white. No shades inbetween. A plug will tell you if you have serious fouling issues but that should be very apparent well before even removing the plug.

If you run race fuels, some are relatively pure and you will be able to read the plug however, those that want to accurately jet a bike use a wideband.

ImageUploadedByThumper Talk1378906231.661436.jpg

ImageUploadedByThumper Talk1378906246.211423.jpg

Obviously a wide and is much better then plug chopping but you can still get in the ball park pretty closely. This plug is out of my warrior that runs on nothing but 93 pump gas it was jetted by chopping and the color is neither black or white. I also have a wideband o2 sensor installed on the head pipe with a home built led sniffer my buddy made. It was chopped before I installed the sniffer set up and was very close. 100% accurate it is not but for those of us that don't have access to a wide band it works fine.

Share this post


Link to post
Share on other sites

No, you cannot.

 

You may think you can but you cannot. Based purely on jetting, a plug looks black or white. White if it is borderline melt down otherwise black. Gone are the days of chocolate brown and seeing a differnece of a single needle clip move. Those days (Mid 70's and past) are long gone with pump fuels. You do not read the plug ceramic at the electrode, you read it down inside where the ceramic meets the metal plug body.

 

Five wire wide band and a digital recorder (capturing TPS/Throttle position, RPM also) is the only way to get accurate results. An LED sniffer is a waste of wffort as you must have the sensor within 18" of the head and at least 2' from the muffler exit. Unless you have 50 lwd segments and number them, you will not be accurate. A wideband measures from about 3;1 to over 20;1. Those values are only useful if can read them in tenths. All testing must be done at steady state throttle positions and under load.

Share this post


Link to post
Share on other sites

Well... My other bike has a nice brown color. Its a street bike  FZ1 but uses the same fuel. a 1000cc but if you look at each of of those 4 cylendars they are 250cc  each. Just thought I would add this piece of info to the discussion

20130814_130135.jpg

Share this post


Link to post
Share on other sites

No, you cannot.

 

You may think you can but you cannot. Based purely on jetting, a plug looks black or white. White if it is borderline melt down otherwise black. Gone are the days of chocolate brown and seeing a differnece of a single needle clip move. Those days (Mid 70's and past) are long gone with pump fuels. You do not read the plug ceramic at the electrode, you read it down inside where the ceramic meets the metal plug body.

 

Five wire wide band and a digital recorder (capturing TPS/Throttle position, RPM also) is the only way to get accurate results. An LED sniffer is a waste of wffort as you must have the sensor within 18" of the head and at least 2' from the muffler exit. Unless you have 50 lwd segments and number them, you will not be accurate. A wideband measures from about 3;1 to over 20;1. Those values are only useful if can read them in tenths. All testing must be done at steady state throttle positions and under load.

Dude I joined this forum when I saw this topic, cause you are full of straight bullshit. Just because you are a mod doesn't mean you are right which It seems you think.

Plug chops are extremely effective still with the pump fuels of today. It is exampled in my machines and my neighbors, and friends machines. I'm pretty good at small engine repair I would say so myself.

So your notion of "it doesn't work because of additives" is complete and utter bullshit. BULLSHIT!

A wide band is just a faster and easier way to tune and is only cost effective if you are constantly changing mods on your bike, making you need to change jetting all the time.

Thanks, Alex.

Share this post


Link to post
Share on other sites

Here are the jets on the bike.

 

starter 72

MJ 180

pilot 42

leak ? (this one is in the bowl) 65

 

I am at 1000 above msl in CA.

 

Funny thing the pilot needle was screwed in all the way and does not have the o ring or spring. Its just the needle. When I open it to 1`.75 turns the bog starts when I crack open the throttle if I dont crack it open it works fine.

Share this post


Link to post
Share on other sites

Main might be large but... that only matters at steady over 7/8ths throttle. Not a concern for now.Worry about it later.

 

No fuel screw spring/washer and oring? And your bike idles and the fuel screw does not simply vibrate out and fall on the ground? Unlikely. It is very possible those parts are stuck in the carb. Triple check.

 

Fuel screw and pilot are for idle only. The amount of fuel between too rich and too lean at idle are no where near enough to affect much above idle.

 

Make sure the passage ways are clear. Ditto with getting a oring/washer and spring. If you have an alloy extended fuel screw, ditch it. Get a brass or stainless steel one. Whikle you are at it, pick up a new OEM pilot jet. Get this part of the carb right before trying to do anything else. All else builds on the pilot and fuel screw. They are always flowing when the bike is running.

Share this post


Link to post
Share on other sites

Yes, get a new OEM 42 pilot jet. Dependoing on extremes in air density, you could possibly in winter need a 45 too, if you want to cover your bases. Figuring out the correct pilot jet and setting the fuel screw is the one area of jetting that has a pretty 'staid' procedure that just requires following the procedure.

 

Fuel Screw/Pilot Jet
Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.
Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly).  Once warmed, slow the idle to the lowest possible speed.
*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***
Turn the screw in until the idle becomes rough or the bike stalls.
if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.
If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.
Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.
If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.
If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.
If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,850 rpm, but go by the spec in your manual.

Share this post


Link to post
Share on other sites

appreciate it. I think since it works best with the screw set in all the way I think I will go down on the pilot jet on size.

Share this post


Link to post
Share on other sites

Here's something thats different on this carb. I dont see this in the manual. Its a carb splitter installed on the carb.

20130911_195628.jpg

Share this post


Link to post
Share on other sites

I do not like those things, they mask jetting issues and hurt the top end. They are called 'Power Now' or 'Scary Fast' aftermarket add-ons. They make your carb act like is smaller and 'fool the jetting'. But they give a slight dead spot at half throttle and a reduced top end. Certainly with that in there, a smaler main is needed. They were deveolped and sold to people that were unable to properly set up the carb. See, the carb on your bike is really quite huge compared to the engine. It has to be to deal with the 13,000 rpm redline. Because of this, low speed performance suffers when trying toi accelerate. Needle selection and setting are critical and having the AP set up right is a must.

  • Like 1

Share this post


Link to post
Share on other sites

i took it off today and going to try the 178 MJ and #40 PJ to see how that works. Will report

thanks William

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×