High speed glazing?

snoosky

XS650 Enthusiast
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Ive recently done some mods on my ‘79. Uni pods, Mikes pipes, shorty muffs and some jetting: 137.5 mains and 30 pilots. The bike runs good and starts in 3 kicks or less consistently. I pulled the plugs after maybe 100 miles and noticed the white porcelain around the electrode is a orangish color. Ive never seen this before. My old Plymouth manual with color pics of the plugs says its high speed glazing and to try a colder plug 608D48C8-4C9B-4247-A328-0A361F9A5EDD.jpeg 5A806650-84CD-4CB0-93EE-1B79D6FFEDEC.jpeg . Anyone seen this? Further jetting recommended?
 
That looks pretty decent,
Was this a high speed plug chop or just removed after returning home?
 
When a plug overheats the porcelain usually takes on a grainy texture. Look at the ground clip. If deposits cover about half its length the heat range is OK. For a myth busting how-to on plug reading, go to www.strappe.com and click "tech topics" then click on "spark plugs." That will take you to Gordon Jennings' classic article on the subject.
 
I run 140 mains in my '78 carbs (same as your '79 set) with similar mods (pipes and pods). You might try 140's, maybe your bike will like them better. If you haven't done so, you probably need to lean the needles a step as well (from stock #3 slot to #2 slot).
 
gggary, if you mean cutting out at full throttle, no. This was just me riding it for a few weeks. And yes, i did lean the jet needle one step.
Tried to get those 140 jets awhile back but pandemic had everything on back order. Ill try again.
 
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