Examining spark plug color

I know that lots of people on this list are pretty sold on the ColorTune plug tool. I didn't have good luck with the one I bought and would like to learn a little more about the old method of evaluating the color of the spark plugs. Here's my list of questions:

1) How long should it take before a new set of plugs are showing their "true colors" and does the type of gas you're running make some difference?

2) Should plugs be cleaned after a mixture adjustment is made? Say you have a pretty black plug in a cylinder that's running too rich. If you lean that out, will it "chameleonized" itself back to a lighter shade or will it just stay black?

3) Color should be read on the ceramic collar below the electrode, right?

Thanks.

 

I've given the advise of posting pics with the plugs on brown cardboard or paper. This seems to be the target color as advised on this site, for keeping the motor "healthy and safe".

1) The plugs will color themselves while doing a "plug chop" in as little as a tenth of a mile. Revving the bike in the garage at 5 grand doesn't do it because the motor isn't under load.

2) You can always wire brush them, but they should burn clean, once up to temp.

3) For the purpose of setting the Pilots, yes. There is a very comprehensive article on reading the WHOLE plug (if someone could post it??) that you need to see.

 

You need to hit the kill switch at 5 grand to get a propper picture.

 

Why? What happens as a result that regular riding doesn't show?

 

If you let the motor drop back to idle, the pilot mixture jets kick in & enrich the mixture.

 

So is the theory that the plugs are continuously changing color based on whether or not it is idling?

 

Pretty much, if you just left your bike ticking over for an hour the plugs would be black as Obama's a***.

 

OK, so let's say I do just that, then go out somewhere and do the "chop." Are you saying that in one short drag my plugs could potentially turn from black to brown?

 

Well, you'd want to give the bike a good run using all the rev bands.

 

The ColorTune Plug is just a handy Tool that takes the guess-work out of setting the Pilot Mixture Screws to their optimum Air~Fuel Mixture to make the Bike IDLE.

The "BLUE" is where the Bike needs to be ... to IDLE.

The BIKE needs a MIXTURE that will let the Engine do MORE than just IDLE.
The Engine needs a Mixture ... RICH enough to sustain combustion when the Engine's Throttles are opened and the Plant transitions from IDLE -to- OFF IDLE.

There is a short period of TIME ... 4 or 5 Rapid Eye-Blinks ... where the Mixture NEEDS to be RICH enough to sustain combustion when the Throttles are opened and FRESH AIR rushes-in ... AHEAD of the MAIN JET FUEL Supply brought-up the Emulsion Tube.

Therefore, ... Fine Tuning requires you ADJUST the Pilot Mixture for IDLE ... and Supplementary RICHNESS to avoid Backfire and Hesitation.

Supplementary Richness means that the right COLOR is "A little bit beyond the BLUE."

<><><><><>

Plug Chops:

You can do Plug Chops with one set of Plugs.
Its a ball-buster.
You need gloves because the Plugs are HOT and you need to read them.

I'm lucky to have a Industrial Park nearby.
Drag down the straight-away ... Kill-it ... and coast to a Loading Ramp wher I'm set-up to Pit-stop.

You can put a RICH Plug in a LEAN Hole.
You can Shoot the Plugs with Carb Cleaner and toothbrush them.
You can do a two-man and llet a partner clean Plugs - B while you are getting the low-down on Set -A.

Once you get "In the Window" of Fine Tuning, ... the ADJUSTMENT to the PILOT MIXTURE Screw is "(My-nute)".

You can get IN it ... and OUT of it ... within the width of a NICKEL.

 

What is the proper speed/RPM's for going a plug chop?

 

when you do these plug chops, if the problem you discover isn't in the range of the main jet, 5/8's to full or the pilot jet and screw, closed to 1/8,
what are you going to do about it? there are no other sizes of needle jets or needles, no other throttle slide angles, or air jets.
back in the day when plugs had color, that color came from lead in the gas.
what color should they be? take a plug out of your late model car, that's the color they should be.
so just save a lot of aggravation and go for a ride

 

good onya polock, thats what i wanted to hear, i kept telling my mechanic mate that according to the info i get on the forums about plug colour, my bikes running lean, he just says no its not, everything is how it should be, he says dont worry, 11000 km later it still goes like the clappers, will turn over 50000km sometime in september.he has been a professional motorbike mechanic for over 40 years, full time,i really should take more notice of him.

 

You can adjust the Pilot Mixture.
The Pilot Mixture varies the Total amount of Richness at Wide Open Throttle.

Fuel from the Pilot Jets is always present.
Adjusting the Pilot flow will alter the performance Mixture.
You can adjust the Mixture from being too Rich to too Lean.

 

what ever you say

 

Oh, yea ...
I totally forgot about Mikuni VM Series Carbs.

But, we'll have to use the informational chart that has been supplied to us to understand:
"Contribution to Fuel Flow"

As we can plainly see from the erroneous Chart supplied, ...
The Pilot Jet and Air Screw supplies Fuel to the Mixture until just about Half-open Throttle.

Then, there is a gap, ... as you can plainly see on the chart, ... when neither Pilot Fuel nor Main Jet Fuel is supplied for the Mixture, ... until just about 5/8ths Throttle, ... when the Main Jet Supply kicks-in.

Everyone knows that's impossible.
Right?
No. Not everyone.

 

That chart is just an algorithm in the style of Yourdon & Coad.

 

i knew i should have made that bigger, there's a thing called a needle jet
and needle jet needle, don't forget them, their important.
that pilot mixture screw is sometimes referred to as the idle mixture screw and the jet is sometimes called the low speed jet, i wonder why?
here read some of these and maybe "Contribution to Fuel Flow" will make some scene, it's really pretty easy
http://forum.highlifter.com/Basic-CV-Ca ... 72049.aspx
www.mikuni.com/pdf/hsr_tuningmanual_021003.pdf
http://www.johnsmotorcycleparts.com/Kei ... g_tips.htm
http://www.ch250.net/techtips/19.htm
http://www.drpiston.com/Cvcarbs.html

 

Rick,are you liking the color of those plugs?Back in the late 70s[stoneage],I used MMO in the Sporty when leaded gas was phased out.Now I use it in the 750 and plugs have a better color.Polock,ya think the alchohol causes leaner burn?I do.

 

to rickomatic, are there any jet adjustments on a 1983 xj 750 maxim with hitachi carbs?

 

There are!
But, nothing quite as simple as a quick "External Adjustment"

There are Replacement FUEL Jets.
Both Pilot and Main.

There are Replacement AIR Jets.
(Same)

A variety of Replacement Diaphragm NEEDLE Jets.
(With varying OD and Tapers)

Complete Diaphragm Assys.
(With Spring-loaded Needle-base's that can be raised with shims)

Replacement Nozzles (Emulsion Tubes)
(Allows you to experiment by fabricating Tubes with graduating AIR Metering Ports to add some Richness.)