spark plug reading help

[wanta86r]

i kow this has been brought up many times, but i seem to be clueless. I have a 38mm a/s carb for my 86R. the motor has a 67mm wiseco piston, shaved and o-ringed head, trx 9 port job, rad valve and an esr atc 5 pipe. Esr did all the motor work, and i bought the carb from them too. Out of the box the carb worked pretty well, but it seems to be missing slightly at wot. i have dropped from a 178 to 175 main jet. i think i need to drop another size, but i dont wanna be running too lean. i am having a hard time knowing what to look for in terms of how thE spark plug should look. The one i just pulled out is black 3/4 of the way around the insulator, and the other quarter is tanish white. is this normal? what am i doing wrong? can anyone post a pic of what a good plug should look like? please help

[Wickedfinger]

How are you doing your plug check?.

[wanta86r]

i havent really done any yet. i just got through my 1st tank of gas. Ive read about doing plug chopps, but dont exactly understand how. what do you think? any help would be greatly appreciated.

[oddball3]

make sure you got a long street or field with plenty of shut down room. make a WOT run for about 300 feet or so. Shut the motor down, but keep your throttle pinned till you come to a rolling stop. pull the plug, you want the electrode to be a cordboard brown color. not the center electrode, but the tab a cardboard brown color. hope this helps you. Thats how we do our sleds.

[wanta86r]

can anyone explain why most of the insulator is black, and has a small whitish tan spot?

[conig]

"can anyone explain why most of the insulator is black, and has a small whitish tan spot?"

most likly the plugs position in relation to the exhaust. My scrambler does this and thats what I was advised it was.

[twgranger]

This is for a banshee but i like to use this for jetting. http://www.dfn.com/benkaren/jetfaq.html

[wanta86r]

can anyone explain why most of the insulator is black, and has a small whitish tan spot?

[bigredhead]

Can you post a picture ? worth a 1000 words LOL..

Kinda sounds like it's the right color... black means rich.. white means lean. brown = good.

[wanta86r]

i hope this pic works so someone can clarify

[bigredhead]

Wow.. that thing looks like new.... you ran a whole tank on that ?

[wanta86r]

no - i have been through a few plugs now- the pic makes the plug look a lot lighter. is definitely more of a black than brown

[42F67N]

Heres a diagram i made for blasterhq on how and where to read a plug to get a proper reading

http://img76.photobucket.com/albums/v232/42F67N/df6d0090.jpg

[wanta86r]

ok so if the entire area that i am supposed to be reading is black, then im too rich?

[42F67N]

if it is dark at the bottom of the porcelin ,* can tilt the plug on a angle and use a flashlight to see but the best way is to "chop " off the threads so * can see perfectly.

[wanta86r]

should the entire porcilain part be dark, or only a small ring toward the bottom

[bigredhead]

and all this time.. i was looking at the plug tip !!!... ie: the metal arm you bend or pull to set the gap....

heh..

[42F67N]

If you install a brand new plug and do the chop correctly * will pretty much only get a reading down inside of the plug,a plug chop cannot be done correctly on a old spark plug thats been used it has to be brand new.

a plug that * have been riding on for a while also wont give * a accurate reading as there are diffrent throttle ranges that need to be choped and read by themselves.

[wanta86r]

so am i too rich if i am getting alot of color towards the top of the porcelain

[42F67N]

if its really black it could be your premix this is in a 2 stroke r right? what ratio and type of oil are * mixing?

I run my 2 strokes a tad rich not enough to effect the performance to where ya notice but enough to make sure im not gonna lean out.

[wanta86r]

its on an 86 atc 250r- i am running 32:1 castor 927 with 110 octane

[42F67N]

Jet your main down one more size and do a chop,put a brand new plug in the bike fire it over and take it for a chop get it running wot preferably up a slight incline to place the engine under a load get it into 5th/ 6th whatever ** top gear is go about 15 secs wide open then pull the clutch in and kill the motor but dont release the throttle or clutch till * come to a stop,pull that plug out and that will give your a proper reading.


32:1 should be ok but id shy away from castrol oils they produce alot of carbon,i burn yamalube which isnt to bad but the best is amsoil.

[wanta86r]

32:1 should be ok but id shy away from castrol oils they produce alot of carbon,i burn yamalube which isnt to bad but the best is amsoil.[/QUOTE]

the oil is castor 927, not castrol, and that is the kind that esr reccommended to me