What do these plug pictures mean???

[gator kdx]

First some background, I've got a 2001 yz250 that I just had ported and polished by Gorr (mo'better). He tuned it to run pump gas (93 octane) and I've been mixing 32:1 with yamalube-2r. The bike also has a pc pipe and silencer.

I recently seized my 93cr250 (after it gave little warning) so I'm probably being over-cautious right now with the yz.

I decided to do a WOT chop yesterday and find a nice long stretch of sand road with a slight uphill grade. It was my first WOT chop so hopefully I had the timing down - in the past I've jetted more by feel. The cr seizure was crank bearing related - but still made me question my 'jetting by feel' method.

Anyhow, I haven't had a chance to cut off the threads on the plug yet so I can't make any jetting observations. Hopefully I can use my dremel to cut off the threads and post some pictures of the porcelain this evening.

I am concerned about something else though. As you can see in the pictures, the metal tip that bridges over the electrode was turned white. From the multitude of jetting posts I've read it seems that this is a result of oil type and plug heat range.

I'm not sure if that is an accurate observation though. Hopefully one of you with more experience than me, knows what this white ashy area means and if it is a problem.

I was able to run WOT for about 20 seconds. It was about 70 degrees with low humidity and near sea level.

Thanks,
John

 

[a454elk]

From what I've seen and heard, that seems to be a little lean. Are you using an "8" heat range plug? There's a great jetting thread running around but you have to search for it. You might just be a little lean on the jetting, but I'd read further to make sure.

 

[gator kdx]

Yes, sorry forgot to mention that, the plug for the test was a fresh ngk br8es.

The manual specifies a br8eg but I can never find those.

My first thought when I saw the plug was that it was probably running lean. But then I remembered all the posts I've seen with people saying that reading jetting from the tip is meaningless (much less from the metal arm thing I imagine).

I think I know the jetting thread you are referring to, it's the 8 page monster with lots of info from Rich Rohrich.

 

[bclapham]

you have to cut the plug open and look at the insulator, but it does look a tad lean.

what main jet????

 

[gator kdx]

The jets are stock size, 178 main and 50 pilot.

I would have expected the port and polish to require leaner jetting if anything, guess I was wrong.

I would say the bike is only running 80% what it is capable of right now. It will pull the wheel up in 1st and 2nd but not enough to be scary. And my tired old cr would pull the wheel up in 1st through 4th with just throttle.

 

[bclapham]

you have to cut the plugs open- its too hard to tell otherwise.

FWIW- my bike has the EG treatment also and i am running 42P leanest clip and 170 main. the first jetting i did from stock was the pilot- now a quick twist of the throttle lands you on your arse! :)

make sure you dont have airleaks etc etc etc

 

[a454elk]

The heat range is right for the bike. I'd say go richer and see what happens, worse case, it'll soil the plug. Sounds like it's starving for fuel. Check your air screw, 2 1/2 out I think. Try a larger main jet, then try the clip, one at a time. Good luck

 

[bclapham]

elk, ive not seen any yz yet that has needed richer jetting than stock, so i think there is something more sinister that needs to be addressed.

btw- you got that RM running yet????? when you comming out to the REM races on saturday mornings???????

 

[whyzee]

I was thinking 178 seemed way too rich to get such a white insulator. Maybe a float bowl adjustment and might be worth checking all the vent tubes ... could be pinched, could be clogged.
Something is not right. I would also run the WOT chop test at 3 runs on the same plug, I'm not sure you're getting enough time on the plug.

 

[a454elk]

It's BEEN running fool, I wanna try out that track in Temecula. I say it's too lean, maybe suckin air on the engine side of the carb.?? Sell it and buy a Zuki:)

 

[whyzee]

Not sure if what I meant to say is what I said. Plug definitely shows a lean condition or a clean condition, but it's not characteristic of the Mo-better porting to have to be so rich. 178mj. You also said the ports were polished...? This is a new one to me as when Eric did mine as well as others I know of, he purposely left the ports "rough". ?

 

[gator kdx]

Went home for lunch and still didn't have time to cut the plug.

However, I did check to see if I was getting an air leak. I fired the bike up and sprayed some starter fluid around the carb - especially around the reed block area and no change in engine speed.

If I have extra time tonight I will try and pull the carb apart and make sure the jets are clean and re-check the float level.

When I put the bike back together several weeks ago (when I got the motor back from Gorr) I cleaned the carb very thoroughly so I doubt that should be the problem.

I don't know how much of a factor it is, but as I mentioned before the WOT chop was on an uphill grade (probably about 5 degrees or so) and in the crazy clay/sugar sand mix that seems to be everywhere in this part of Florida.

The sand is pretty deep and loose, is it possible that the lean condition is largely because of that? Or should I keep looking elsewhere.

Thanks again, all the feedback is a very big help.

 

[GhostRider32]

Humm..... everytime I tried the plug pic. links, I got an "you don't have permission to access this page". Any ideas?

 

[gator kdx]

I was getting a similar error previously, don't know if it's the same thing or not.....

Here is the thread that helped me fix it: http://www.dirtrider.net/forums3/showthread.php?t=92163&highlight=pictures+registered

Basically, long story short I had to clear the DRN cookies and then re-logon (username & password) to not only the forum but also the gallery.

Hope this helps you.

 

[GhostRider32]

Thanks for the help, I did all of that but it still dosen't work. :(

 

[canyncarvr]

The following comes from memory of something read...and I haven't found it repeated in a short search. Correction with facts or by someone of respected stature appreciated.

There are two places to check for a/f mixture..one being the base of the insulator, the other being the flat of the threads. IF that is ineed so, it doesn't look like you have a huge lean problem to worry about.

Still...the mixture ring at the base of the insulator is where you need to look. There are inspection tools that allow you to see that ring without cutting the threads off.

RR notes such a tool here.

Note that the mixture ring may not be visible all the way around the base. It starts 'under' the ground electrode (that metal 'tip' bridging thingy) and goes further around the insulator the longer the run. On 1/4mile runs of only a few seconds, this ring may not be all the way around the insulator.

Twenty seconds is a bit different. Should be plenty.

'Can't find an -eg..' ??

Got 'em in most shops 'round here..and certainly available thru rockymountain. Good plugs!

...change the plug once in awhile, though. At least annually (sez me....no bibliography notation available).

No matter how good you're jetted a spark plug leads a tough life. Just 'cuz it still works doesn't mean it shouldn't be replaced.

Post a pic of your mixture ring when you get those threads off! ;)

 

[gator kdx]

Alright, finally got home from work and cut the threads off the plug.

The results are not at all what I was expecting. All the threads I've read say you want a nice tan ring about 1mm thick.

With the previous pictures showing a generous amount of white ashy stuff on the end of the wire 'bridge' I expected to see a very narrow ring.

Well from the looks of the pictures I just took if anything I am running rich???? on the main jet.

I am seriously confused and any help is appreciated.

Thanks,
John

 

[wibby]

I would also run the WOT chop test at 3 runs on the same plug, I'm not sure you're getting enough time on the plug

Why?

I've never had enough room to do a chop longer than about 6 seconds and I seem to get good reads

Here's two I did on Sunday on my kdx

Humm..... everytime I tried the plug pic. links, I got an "you don't have permission to access this page". Any ideas?

Only subscribers can view images

Membership does have it's priveliges! :cool: