Cutting open plugs for jetting (pics)

Rich Rohrich

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I've been working on a description of various plug conditions and how to identify them. I haven't completed the text but I thought you guys might like to see a few of the pictures.

http://four-stroke.com/plugs/plugA_shell.jpg

http://four-stroke.com/plugs/plugA_noshell.jpg

http://four-stroke.complugs/plugb_shell.jpg

http://four-stroke.com/plugs/plugb_noshell.jpg

http://four-stroke.com/plugs/plugc_shell.jpg

http://four-stroke.com/plugs/plugc_noshell.jpg

http://four-stroke.com/plugs/plugd_shell.jpg

http://four-stroke.com/plugs/plugd_noshell.jpg


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Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein
 

Rich Rohrich

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I'll post it here on DRN , and on Eric's site.
 

Rich Rohrich

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They are all jetted pretty close except for C, which inspite of being white is ~2 sizes too rich on the main for MX, but jetted perfectly fine for trail riding, or woods work. The plug is running a bit too hot for the application.

Just so the "More oil is Bad 50:1 Club" is clear on things, Plug D is from an RM150 running 18:1 and ridden by a complete motosquid (ME) on a really tight track that sees very little WOT running. So much for the belief that more oil will foul plugs
smile.gif

The plug isn't running hot enough on plug D to properly clear the deposits from the nose of the insulator which is the ONLY reason it is chocolate colored, it should be much lighter colored (whitish /tan) if the plug were running at the proper temp, but Plug D should give you a pretty good idea what the fuel ring should look like at the bottom of the insulator. That's where you want to look to read the Main jet.
 
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cr250john

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Jun 14, 2000
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Rich,
Really cool!
If your remember last month I took a lathe to the plugs on my CR250 and the kids CR80.

The nose of both bike plugs look cleaner than your plug "D" and the CR250's plug ring is similar in color to "D" and starts approximately 1/16th above the metal base and is 1/16th thick where yours looks to be right at the base. The CR250 was running a BR8ES.

The kids CR80's plug has a very light tan ring that is right at the base and is a hair bigger than 1/32nd and looks just like your "D" plug with a white nose. That plug was a BR9ES. I did go one size larger on the main with the kids bike because is seemed to be lacking a little in top end.

Side note: Were these pix taken with a digital camera or with film and then scanned? I have access to a film camera and macro lens so maybe I'll get some pix of my plugs and we can compare notes.
Great addition to the forums no matter what!
smile.gif

Thanks!

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cr250john
Mine '00 CR-250 '95 Yamaha Virago XV-750
Kids '01 CR-80's
 

Rich Rohrich

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John - Sounds like you're pretty close on the jetting. Good job.

I used a $130 3Com Digital Webcam to shoot these : http://buydirect.3com.com/iom_dcms/b2c/catalog/detail.html?SKU=003718-00&SM=HOME_OFF

My expensive Digital camera can't do as good a job with detail shots like this. The 3Com cam has way better Macro capabilities, and a choice of lenses.

------------------
Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein
 

steve125

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Rich you can hear the stampeed of riders running to their old plugs and compareing them to your pics. Good stuff Rich.
 

tileman

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Oct 18, 1999
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Well I have been jetting in my 00 cr 250.
Was jetted at main 175 slow jet 48 with
100 octane union 76 with hp2 32/1 mix
Still running rich with gooo out the silencer
So I jetted to main 172 slow jet 42
Still a bit rich but 75% better
Then I started running maxima super M oil at 32/1 with the same 100 race gas a before
WOW did a plug check and running lean the plug was white.
So I turned in the air screw to about 1 turn from out and it now looks like the frist plug (D) in the pics so I would like to know is the hp2 oil too much lubricant
Or is the maxima oil not enough.

Thanks Tileman.
 

wrench

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COOL VERY COOL!!!!

wrench
 

cr250john

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Rich - All,
Here are links to the plug chop pix from my '00 CR250 and the kids '01 CR80 that I promised weeks ago.
Rich - Thanks for the suggestion of using the computer video camera. I used the one from a video conference setup I have.

CR250 plug click here

CR80 plug click here

What do you think of these?
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cr250john
Mine '00 CR-250 '95 Yamaha Virago XV-750
Kids '01 CR-80's
 

shifter125

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Sep 11, 2000
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very nice pics. how are you able to verify the correct timing. i read on TSR that the rim of the center electrode will tell you if the timing is on. is the timing on on all of the these? or are there some that are off - which is which?

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SUZUKI-BIREL 125
 

Rich Rohrich

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The specifics will be part of the article, but plug C was running a high dose of ignition accelerator and needed the timing to be backed off some.
 

Rich Rohrich

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Paul - I've done some testing with Nology Hotwires and a couple of other "add on" products in automotive applications, and didn't find anything in their operation that would change the plug reading, or anything else for that matter
smile.gif


REAL, performance ignition systems like the Jacobs or MSD, will tend to change the look of the tip of the center electrode, and has some effect on the look of the ground strap.

Did you have some specific product in mind?
 

johnv

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Mar 10, 2000
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Thanks for the pics Rich!

How old are those damn things??? My plugs never look that dark. If anything, they usually look like CR250John's plugs.

Thanks again!
John
 

WWR

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Jul 15, 2000
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Rich,
I dont remember the name of the plug-cap spark-enhancers, but I can run out and get you a pic of it. If I remember right, most of the large writing on the product is in English, but the detail stuff is in Japanese (I cant read it). Actually, I thought these things might be more usefull in helping with the YZ400/426 hard starting problems than anything else. Its worth a try.
Paul
 

Rich Rohrich

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The only people who have problems starting YZFs are the ones who kick like a 12 year old girl having a HISSY FIT
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Jeff Howe

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Apr 19, 2000
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Ahhh... a little generalization for those who would never admit to it. Rich, you might have offended some there but will never know it. hehehe
 

Rich Rohrich

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I generalize all the time. I just make every attempt to confine it to things that don't really matter
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Rich Rohrich

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What's may be even funnier is how many people believe it takes some sort of super human effort to start a YZF
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Rich Rohrich

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Paul - There isn't much chance that a plug cap alone is going to make any significant difference on a properly functioning OEM YZF ignition system. I realize that fact won't stop people from selling all kinds of bolt on junk.
frown.gif

Hard starting issues on YZFs seem to be a direct consequence of two-stroke riders who are unfamiliar with big bore four-stroke starting procedures. I don't really believe four-strokes are harder to start, but the procedure is certainly different. Even at 13.8:1 compression my YZF has always been a first kick starter hot or cold, IF I follow the steps to start it like a BIG four-stroke. Attempting to start it like a two-stroke is just an excercise in futility. Not surprisingly, the AF500 two-stroke shares many of the same traits. Treating it like a 500 and it's a first kick starter. Treat it like a 125 and you'll kick till your leg falls off, or it kicks back and breaks your ankle
smile.gif
 
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