Re: First time jetting. How does my plug look?

Den 23 /
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http://www.strappe.com/plugs.html

"So how can you tell whether you've chosen the right heat range? It's easy: a spark plug should be getting hot enough to keep its insulator nose completely clean, with all deposits burned away, but not so hot that its electrodes show signs of serious overheating. These are things to look for on a new plug that has been subjected to a few minutes of hard running. After many miles of service insulators acquire a coating of fuel deposits, with some coloration from oil in two-stroke applications, and there will be some erosion of the electrodes even when everything is normal. Don't try to read old spark plugs; even the experts find that difficult. New plugs present unmuddled information about what's happening inside an engine, and can give you a complete picture after just minutes of hard running. At least they will if they're running hot enough, and that should be hot enough to keep the insulator clean.

A lot of amateur tuners, some of whom are fairly successful, will look at some plug freshly removed from a two-stroke engine and offer advice based on the color of the oil deposited on the insulator nose. In fact, if the plug is hot enough there won't be any color, and if there is that still has nothing much to do with air/fuel mixture. If you think about it you'll realize that the only color you can get from an air/fuel mixture is the color of soot. When the mixture trapped in an engine's combustion chamber has more fuel than can be burned with the available air, then combustion will be incomplete and the excess fuel will remain as soot, which is not brown or tan or magenta or any color other than black. And if your engine's mixture is too rich, the sooty evidence will be present on the spark plug's insulator, in a very particular area.

We cannot stress too strongly the need to give spark advance your closest attention, because excessive spark lead is the most frequent cause of detonation, which is a real engine killer. You can't stop advance-produced detonation with a cold spark plug, nor with anything but a wildly over-rich mixture. Also, excessive ignition advance has a bad effect on performance. We ran a 250cc road racer at the drags a few months ago, and found that retarding the spark about five degrees from the manufacturer's setting raised the trap speed from 106 to 110 mph. Similarly, there's a 125cc motocross machine residing in our shop which runs a lot stronger and cleaner since it has been retimed for less advance, jetted leaner, and been given a hotter spark plug."

http://www.strappe.com/plugs.html

This single post is part of a larger thread. Start from the top or view this post in context.
Subject Written By Posted
  First time jetting. How does my plug look?Topic by: Art Vandelay Art Vandelay 07/13/20 01:44PM
  Re: First time jetting. How does my plug look?Re: Jeff Parr Jeff Parr 07/13/20 01:46PM
  Re: First time jetting. How does my plug look?Re: Nicholas Scholten Nicholas Scholten 07/13/20 02:02PM
  Re: First time jetting. How does my plug look?Re: P D P D 07/13/20 02:16PM
  Re: First time jetting. How does my plug look?Re: Art Vandelay Art Vandelay 07/13/20 02:26PM
  Re: First time jetting. How does my plug look?Re: P D P D 07/13/20 02:35PM
  Re: First time jetting. How does my plug look?Re: Dirty30 Dillon Dirty30 Dillon 07/13/20 02:29PM
  Re: First time jetting. How does my plug look?Re: Jay Rivett Jay Rivett 07/13/20 02:32PM
  Re: First time jetting. How does my plug look?Re: Art Vandelay Art Vandelay 07/13/20 03:43PM
  Re: First time jetting. How does my plug look?Re: Jay Rivett Jay Rivett 07/13/20 04:09PM
  Re: First time jetting. How does my plug look?Re: Nicholas Scholten Nicholas Scholten 07/13/20 04:49PM
  Re: First time jetting. How does my plug look?Re: Dirty30 Dillon Dirty30 Dillon 07/13/20 04:58PM
  Re: First time jetting. How does my plug look?Re: Jay Rivett Jay Rivett 07/13/20 07:22PM
  Re: First time jetting. How does my plug look?Re: Dirty30 Dillon Dirty30 Dillon 07/13/20 08:53PM
  Re: First time jetting. How does my plug look?Re: Art Vandelay Art Vandelay 07/15/20 09:45AM
  Re: First time jetting. How does my plug look?Re: Art Vandelay Art Vandelay 07/13/20 07:34PM
  Re: First time jetting. How does my plug look?Re: Ted Kenny Ted Kenny 07/14/20 09:20PM
  Re: First time jetting. How does my plug look?Re: Ted Kenny Ted Kenny 07/16/20 10:03PM
  Re: First time jetting. How does my plug look?Re: Den 23 Den 23 07/15/20 06:42PM
  Re: First time jetting. How does my plug look?Re: Tri-ped Dave O.D.B. Tri-ped Dave O.D.B. 07/19/20 02:15PM
  Re: First time jetting. How does my plug look?Re: Jay Rivett Jay Rivett 07/19/20 02:47PM
  Re: First time jetting. How does my plug look?Re: Graham Motzing Graham Motzing 07/19/20 03:09PM
  Re: First time jetting. How does my plug look?Re: MICHAEL FRENCH MICHAEL FRENCH 07/19/20 08:41PM
  Re: First time jetting. How does my plug look?Re: Hepatitis J [OFMC] Hepatitis J [OFMC] 07/19/20 09:42PM
  Re: First time jetting. How does my plug look?Re: MICHAEL FRENCH MICHAEL FRENCH 07/19/20 10:00PM
  Re: First time jetting. How does my plug look?Re: P D P D 07/20/20 08:51AM
  Re: First time jetting. How does my plug look?Re: Jay Rivett Jay Rivett 07/20/20 07:21PM
  Re: First time jetting. How does my plug look?Re: P D P D 07/20/20 07:43PM
  Re: First time jetting. How does my plug look?Re: Marc Friedman Marc Friedman 07/20/20 11:00PM
  Re: First time jetting. How does my plug look?Re: Den 23 Den 23 07/20/20 11:38PM
  Re: First time jetting. How does my plug look?Re: Dirty30 Dillon Dirty30 Dillon 07/21/20 12:18AM
  Re: First time jetting. How does my plug look?Re: Den 23 Den 23 07/21/20 09:06AM

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