plug chop take II

[1998RM250]

Okay guys after my first failed attempt at a plug chop, and thanks to everyones help I think I got it right this time...
I ran a tank of 93 mixed with yamalube 32:1 through the bike yesterday trail riding (mixed on and off the throttle) and pulled the plug when I got home. A little bloodshed, lots of metal slivers, a broken hacksaw blade, and 1/2 hour later here is the result. I find it weird one side of the plug is completely covered in carbon, and the other side on the bottom where the fuel ring should be isnt at all. Can you guys give me your opinion on this? I'm running stock jetting 01' RM 250 N3WK needle, clip 3rd position (stock says 2nd), FMF gold series pipe, and V-Force Delta reeds.

 

[whenfoxforks-ruled]

Way too blurry, and the burn ring appears covered up! Covered by coolant/tranny fluid? If the 1st pic was clearer, it almost looks to be there, lite gray, but? Or, I do not have my glasses on and you are running black paint? Warm the bike up, take a run in the top end and clear the engine out. Put a new plug in, warm it up and take a run through the gears and back. On the way back, wfo, clutch in and kill it. Plug chop, for reading the main, only. The main can be felt by seat of pants also. You can not jet a bike with issues. Even the blurry pic is saying coolant/tranny fluid, somethings not normal. Vintage Bob

 

[1998RM250]

Hmmm i dont appear to be losing any coolant or tranny fluid at all. There is no burn ring at all except that black stuff all over the ceramic part as you can see, and what your thinking is the grey on the bottom is actually the clean ceramic. I know my cell phone pics suck, but I'm trying to explain the best I can. What looks like the burn ring covers the entire ceramic part, except on half of the bottom side as you can see.
I just dont understand, the bike seems to be running decent except it loads up pretty easy if your just crusing.

 

[whenfoxforks-ruled]

Found it, http://www.dirtrider.net/forums3/showthread.php?t=92818 ,the burn ring is there. Vintage Bob

 

[helio lucas]

pulled the plug when I got home.

the plug has to be taken right after you kill the engine! any more time than that and you will not getting a valid reading.
see my post on your other thread.


read this link carefull and don´t jump any section. read two, tree times if needed. print it and take it with you...

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

the article refer to a page on eric gorr website. here is the update:

http://www.eric-gorr.com/carb cleaning and jetting.pdf

:cool:

 

[1998RM250]

thanks again, great info. I wish I had a better camera to show the detail of the base of the plug. Is it possible the fuel ring is covering the entire ceramic part of the plug? Upon close inspection with a magnifying glass, the part that appears grey and suspected as the burn ring right at the bottm actually is the ceramic part of the plug.
I just don't understand why it would only be on half the plug? I was thinking of raising the clip another notch, but I'm torn between a rock and a hard place right now.

 

[julien_d]

When you do a plug chop, you are looking for the condition at a specific throttle opening. Putting in a new plug, trail riding a while, and then chopping the plug when you get home is an exercise in futility. It's not going to tell you a darn thing with any measure of accuracy. Read through the links above, and be sure when you are doing your plug chops that you are using the correct throttle position for the circuit you would like to read.

 

[1998RM250]

Yeah I understand now, but with the plug looking black like that and a little wet when i pulled it is it safe to say its still running a tad rich? I don't want to raise the clip another notch and have it be to lean and blow up. It doesn't appear this plug was overheating, so I'm guessing it would be okay to try for one ride at least?

 

[whenfoxforks-ruled]

My weed wacker plug does not look that dark/sooty. Is it soot or oil residue? Does the plug have an odor? Bubbles in the radiator? Sweet order to the exhaust? The timing is retarded? It could also be because the plug never got hot enough? Back to the coolant. I do not think its jetting, entirely. Vintage Bob

 

[1998RM250]

The plug kind of smells like charcoal, and I don't smell antifreeze burning at all. It was a little oily when i pulled it, but the black stuff you see in the pics is dried on. I noticed that the radiator on the right side of the bike going back into the head was cool to the touch, while the one on the left seemed pretty warm. I'm guessing thats normal and probably means the radiator's doing their job? I also noticed after a pretty good ride that the jug itself didnt even feel that hot, I could touch it and not get burned. The bike has not ran good since I got it until now its runing "decent" and the previous owner let it sit for nearly two years.

 

[whenfoxforks-ruled]

Wonder if this is the bike that can have the base gasket installed backwards? I will sleep on that one. Radiator and cylinder should be about the same temperature, about. Can you see the coolant flowing, engine running and cap off? What kind of plug are you using? Vintage Bob

 

[1998RM250]

hmm you mean like the gasket upside down? I'm pretty sure it only went on one way, but does it matter which side it up or down? The cylinder head and the radiator were probably about the same temp, but neither were extremely hott to touch after riding.
I will have to put a new plug in (B8ES) and see if it's flowing with the cap off.
Vintage Bob you are a great help, and I thank you very much.

 

[whenfoxforks-ruled]

If you are going to run the cheap plugs, at least get the resistor plug, BR8ES. It may save the ignition$$$ Some base gaskets can get put on wrong and block the coolant flow. Dead blank on the RM250 though, its been a while. Vintage Bob

 

[1998RM250]

Well i raised the clip to the 2nd position (stock setting) from the 3rd and put in a new BR8ES plug. The bike seems to be a little faster and rev's out much cleaner now, but what I really noticed is it sounds different. When you rev it up its got that ring ding ding type sound and sounds a little more tinny if that makes any sense to you guys... Before it didnt sound like that at all, so hopefully it's not running too lean. If I'm riding it tomorrow what would be a sign that its running lean that I should look for? I just really don't want to blow up this top end ugh!

 

[whenfoxforks-ruled]

Ride it in the area of concern, kill it and check the plug, wet or dry? By rights, you should put a mark on your throttle housing and divide your throttle throw in quarters, quarter, half and so on. You have your pilot set correctly, adjust the air screw till it revs the highest? How many turns out are you at? The clip, if you can put the choke on, and it runs better is another way of seeing if its lean. Vintage Bob

 

[1998RM250]

I'm at 1.5 turns out on the air screw, it doesnt really seem to do anything?
Rode it around for about 5 minutes and the plug is dry, but you can see the carbon buildup starting again. I dont understand what all that black carbon is from, its not burning any case oil and I don't appear to be losing any coolant as well. Tomorrow I am going to do a compression test as well after I ride, the new rings have about 5 hours on them.

 

[whenfoxforks-ruled]

Ineffective air screw adjustments, to the lean side. Try the choke trick. Does it respond better with the choke on, off idle? A compression test at the 5 hour mark, have you been keeping track? Vintage Bob