width of main jet 'ring' on sparkplug

[r.2 stroke]

Hi,not sure if this is posted in the correct forum,but,i have read alot of threads on reading sparkplugs...and i may have missed it ...but....when one is reading a sparkplug,and in particular,the black 'ring' that you look at to see if your main jet is in the ball park at the very base of the plug,what sort of width would the ring be,to be considered correct,and therefore your main jet o.k?
Thank you

 

[yam 3]

I think that it is supposed to be 1-2 mm

 

[Rich Rohrich]

It depends on the fuel and the variance you'll see in the maximum load and atmospheris conditions. If the load and conditions stay pretty consistent then good fuel will allow you to push the ring till it's barely visible. If the conditions are varied or the fuel is poor then you need a much larger ring as a safety margin.

Unfortunately there are only rule of thumb answers with few absolutes.

 

[bclapham]

when talking about this "ring" are we talking about the black oil ring at the last few threads at the end of the plug?

also, if we have the pilot or clip not well set, will this make this reading worthless?

i really struggle with this jetting thing, kinda like a pilot flying blind- i dont trust my gauges- i know its rich, but i am already running several sizes leaner on the jets! i am hoping this smaller bike will be easier to setup- that rip snorting 250 didnt see WOT for prolonged periods, LOL!

thanks

 

[Rich Rohrich]

Bruce - Thre are a few pictures in the thread below that should help explain the jetting ring we are talking about.

http://dirtrider.net/forums3/showthread.php?s=&threadid=48348

 

[r.2 stroke]

thanks for your replies guys,..Rich,i might sound like i am trying to pin you down for an exact measurement of the width of the mixture ring,and i understand what you have just previously said about pushing the ring till it is barely visable if conditions allow(fuel,atmosphere,etc),but for a very average rider like myself,on my kdx 220,using pump gas and basically set up from the info off Canadian dave's site,how thick would the ring have to be,to be considered too rich on the main jet?like over 3mm?Just need a ball park reference........sorry if this sounds like a pain in the arse.

 

[Rich Rohrich]

Originally posted by r.2 stroke
how thick would the ring have to be,to be considered too rich on the main jet?like over 3mm?Just need a ball park reference

Honestly, if you are just an average rider just running in the woods on pump gas you should use the ride and feel method Eric Gorr discusses on his website and not worry about WOT main jet plug readings .

http://ericgorr.com/techarticles/carbtuning.html#i

 

[bclapham]

thanks for the link Rich- seems like i have been the victim of another old wives tale, LOL.

i would be happy to chop up a plug or even splash the cash on a plug reader, however, i see no point for me- unless someone opens up a nice slight uphill flat stretch of land right next to all the tracks i ride, then a WOT would be meaningless.

i will figure this ride an feel thing, i just need to stop talking to people- my mate seized up his rm the other day with a 430 main and today the dude next to me had a full blown bills rm running MR2 and a 490 main! i had a 420 in and C12 10%MTBE with super M 25:1 and the top end was fine. i messed with the pilot, and even with it well set by the fast idle wind out the air screw peak rev method, the bottom was quite burbly and i was getting some spooge. i think i will try steves trick with the agressive ignition advance and keep an ear out for pinging when its wide open. ive got some of those denso plugs coming also with the funky strap for peace of mind too. i expect it might be this "REV" pipe i have on, but the bike wouldn't do much until i got to 1/2 throttle and a dab on the clutch and it then came on real nice with a massive midrage hit. i have a quite fast friend that rides a kx250 and he loved it!

btw, this bike rocks, awesome cornering, nice power and my first mess with the showa forks wanst too far off...looks like i can keep that 4-stroke on hold for another year or two!:yeehaw:

thanks

 

[bclapham]

a slight U-turn here, i cut the plug apart anyway- good job i did, i dont think the gray area counts as a "carbon ring", although i could not tell, it seems like it was detonating bad enough to vibrate the plug loose! ive gone up to a 440 now and i will find out more tommorow, although i will be riding a harder packed SX type track rather than the deep loamy hilly track where this plug was run.

 

[whitesands26]

Originally posted by bclapham


i will figure this ride an feel thing, i just need to stop talking to people- my mate seized up his rm the other day with a 430 main and today the dude next to me had a full blown bills rm running MR2 and a 490 main! i had a 420 in and C12 10%MTBE with super M 25:1 and the top end was fine.
thanks

What kind of bike do you ride ? Those are some pretty rich main jets...What's the temps and altitude where you're at ? What were the conditions when those guys were running those fat jets ?

 

[bclapham]

02RM144 it comes with the TMX38mm carb. it was about 4000 ft and a very hot so cal day- seems this bike needs big jets!

 

[bclapham]

OK, so this was my second run out on this bike. I was at a different track this time, hard packed, tight and twisty with a couple of doubles that i couldnt figure and just kept rolling them,LOL.

Based upon the last plug and my unknown visit from the detonation fairy:) i went up two on the main to 440, but i advanced the ignition to try and clean up the bottom end a bit. Holy moly, just these changes and the bike was much faster. However, i am still getting way too much spooge, even though i went down to a 25 pilot and i am at the leanest on my needle, i still think there is more response to come on the bottom circuits and to be fair my gas is a bit too old. i will buy more jets and a lleaner needle i think.

here is the interesting thing, i cut open the plug and it appears to have two rings!:eek: the first ring is about 1mm, then you can see the white ceramic/insulator and then there is another ring of 1mm. also, both rings are slanted from the perpendicular of the plug, one side of the insulator is tan whilst the other is still white.

i appreiciate that this plug is not from a WOT chop, but i think it is interesting all the same, i would like to hear from the experts to see if indeed this is classed as two rings or just a wide one ring. pic to follow

thanks, BC

 

[bclapham]

here it is

 

[bclapham]

if you look closely, you can see the slant of the rings and also the difference in colour on the two sides of the insulator

 

[Jaybird]

I'm no expert, but it looks very much to me like the plug has been used a bit and that you have simply burned away some of the previous carbon.
You may want to use a brand new plug to check out the ring for your main jet.
Using a plug that has been ran awhile, especially with different jetting, can be an exercise is futility.
The slant thing may just be charectoristic of the turbulants in your jug.

 

[Rich Rohrich]

Bruce - Bruce if you didn't start with a new plug then there is no way to know exactly what you are looking at. Basic instrument calibration concept here ;)

From a 100 foot view it looks like 1 hopelessly wide, hopelessly rich ring, but I wouldn't bet my engine on it.

 

[flynbryan]

Rich, Thanks for the old thread(very informative), and for the Eric Gorr link. I can honestly say I have my Crf ridiculously rich. I have also been one of the ones that would try and read a plug by the top of the porcelin. These plugs that have been shown(by both the old link and by bclapham)in my lack of knowledge would have looked horribly lean. I'm now going to take the knowledge I've gain here and feel how my bike feels when its not being over fed with fuel. Also, this is a question I've had as I've read all these posts; Do these plug reading methods/ looking at colors still hold true for Strokers as well? Thanks again, and now this weekend I will be trying the "ride and feel" method. :thumb:

 

[bclapham]

Originally posted by Jaybird
You may want to use a brand new plug to check out the ring for your main jet.

Originally posted by Rich Rohrich
if you didn't start with a new plug then there is no way to know exactly what you are looking at. Basic instrument calibration concept here ;)

it was a brand new plug guys!:) come on, what do you take me for LOL! :confused:

Like i said, it was never going to be a "proper" experiment, since this plug was just taken after a days riding, just as the previous plug was taken after a days riding but with a two-smaller main jet.

so here is my prognosis, yep its definately hopelessly rich now. Before it was rich on the lower opening circuits but dangerously lean on top and showed no ring at all. Bottom line is, i now am more confident that i can play with the pilot and needle and clean up those circuits and then take it from there, i might even look for a long straight out in the desert somewhere so i can do the proper experiment on just the WOT.

it will be interesting to hear how to do this with a 4-stroke, will it work properly since when we hold it WOT isnt it gonna keep popping on the rev limiter?

cheers, BC

 

[steve125]

Bruce I would not think it's hopelessly rich, as your testing is full of holes at the moment. You need to go back to the first track that gave you the lean setting and see if the change to the bigger main looks better on a new plug. It seems that your not riding as fast on the second track and that can make your setting look rich when it's not.

 

[Jaybird]

A new plug that has a day on it is not new, Bruce. What I'm talking about is mounting a new plug then immediately checking your main jet. Which means you immediately take the plug out after doing the throttle chop at load. Perhaps take another plug with you so you can return to the pits with.
Riding it at all after this kills the recipe.
Use the cheapo plugs to tune with.

 

[bclapham]

Yes, i understand that. Like i said, this was never going to be the "proper" experiement since it was never my intention to do a proper plug chop. if i hadnt cut the first plug apart, i would not have known that i was lean on the main- i couldnt hear detonation and niether could an intermediate class rider, however, the plug was vibrated loose so that was a good indication which was confirmed by opening the plug so it was a very worthwhile experiment.

so at the end of the day, no i have not done the best experiment, however, i have a much better idea of what is going on and when you think of how far i have come with this bike in 2 rides at massively different tracks i dont think i am doing that bad since i had no where to start from- the bike came to me as a basket case missing half the engine, and i dont think the jetting was that good from stock- a list of changes is- v-force reeds, 144 kit, FMF pipe etc etc etc.

believe me, i am not daft- if i had a nice piece of land where i could do a WOT then i would, but what would that mean considering it would be at a different elevation to the tracks i normally ride.

cheers

BC

 

[Jaybird]

Are you basing the conclusion that you were lean on the main from the plugs you show above? I wouldn't reach that conslusion after seeing them.

btw...you can reach WOT in first gear.

 

[bclapham]

no, i am basing that on several observations- look at the pic in post #9 (rm144plug1) i cant see a ring on that plug at all like the rings on the plug pics that are in the thread that Rich put the link up for. In addition, the bike was detonating enough to vibrate the plug loose and when i put a larger main jet in with the same pilot and clip, the bike was noticably faster, the plug stayed put hense my conclusion that the main was indeed to lean. I emailed steve about this also, since he has helped me out with many of the aspects of getting these big bores working well- he was of the same conclusion that the first plug suggested the bike was too lean also.

 

[Fark]

Check out Kevin Cameron's Sportbike Performance Handbook. There's a great section on reading plugs in there...