I wanted to throw a question out for you "seasoned" harley guys. I am very familiar with the truths and myths of readingspark plugs in acager, I used to drag race a little. When itcomes down to fuel and timing, is there any differencesin what isgood for an air cooledVtwin? I'm a believer that the color of the porcelain will only indicate major extremes, or additives in the crappy fuel we have these days. The small amount of experience I have with liquid cooled Vtwins pretty much backs that theory up, but not enough to where I would swear by it at this point. How about dyno tuned bikes? What do your plugs look like? Anyone ever pulled a fresh plug right after a full throttle run?

 

Sure have....what we are looking for in a Harley is a white, soft white or light Grey, porcelain tip with evidence of a fuel ring around that porcelain tip just like a halo....the halo or ring will be a light to med Grey color. The timing line should be even with the positive electrode to the porcelain tip for prefect timing, the advance timing will show the line on the negative elect robe closer to the threaded body, a retard timing line would be indicated up and around the bend on the negative electrode.

 

Good deal, thanks for the reply. I found a tech post about it on here after I posted this that did a pretty good job. In general, what total advance do you want on a stock 88 or 96 inch?

 

Well the EFI bikes will advance up to 50* but run in the 25*to 35* area the most

 

About a month ago someone posted a great pic of about 20 plugs ranging from very rich to way too hot/lean. But I can't find it without the search. Could that person please repost that pic?

 

www.4secondsflat.com/Spark_plug_reading.html