plug colour/jetting

hi folks , what would your opinion be on the colour of my plugs ? the outside is sooty , indicating too rich a mixture and the earth and centre electrode is a nice chocolaty brown indicating correct mixture.
the bike has only 750 miles on her after a full rebuild by myself so am not revving above 3000 yet and allowing the engine to labour , gently running in !

all opinions gratefully recieved , thanks in advance .
andy

Frankly, I am old school, and have knowledge of reading plugs back when lead was in the fuel.

FWIW, my guess is rich mixture and/or late timing.

What heat range plug?

Slick

texasSlick said:

Frankly, I am old school, and have knowledge of reading plugs back when lead was in the fuel.

FWIW, my guess is rich mixture and/or late timing.

What heat range plug?

Slick

Click to expand...

I agree, but not so bad.
Piero

texasSlick said:

Frankly, I am old school, and have knowledge of reading plugs back when lead was in the fuel.

FWIW, my guess is rich mixture and/or late timing.

What heat range plug?

Slick

Click to expand...

hi slick , plug is an ngk b6es , my thoughts at the moment are dropping the needle a notch and see how that goes , when I've a few more miles on her ill get a feeling on the main jet portion of the rev range .
regards
andy

andy johnson said:

hi slick , plug is an ngk b6es , my thoughts at the moment are dropping the needle a notch and see how that goes , when I've a few more miles on her ill get a feeling on the main jet portion of the rev range .
regards
andy

Click to expand...

My thoughts exactly.

NGK b6 should be good.

Slick

Look on the bright side, the black soot that will coat the top of your piston crown will prevent the piston from getting too hot. As you have not revved above 3K I would have now tuned the carbs with a Colour Tune done on a warm engine in THE DARK!!!!! if you only have to move the pilot screw a fraction-it will make a difference!

Before to change the throttle needle groove please let us know what carbs you have on.
Between the stock 930/7/8 with the pilot screwed and the later with pilot in, there are differeces of tuning.
Look what cut is the slider.
930/7/8 for P11 was the lean cut 3 (with 107) but the same carbs for Atlas/N15/G15 was tuned with the rich cut 2 (with the 106).
I run with stock 7/8 carbs with:
cut 3 hard anodised sliders;
220 and 106 jets;
Long jet holder;
Float 2 mm under the top;
throttle needle 4T - (2 I/D GROOVES) (AMAL 622/124) with center clip;
new air screw.
Ciao
Piero

I always run BP 7ES. Using the seat of the pants method the current Commando is running a 3.5 slides, 107 needle jets with the needle on the middle position. Next test run will be with the needle in the richest position. I know this sounds really odd. I have long ago disregarded the book specs, using them only to get in the ball park. There is also a big difference between jetting for the mid range first (approx 5 or ten miles around 4000rpm) getting that spot to run to the right color THEN trying to jet for low speed running. So many things converge at idle and just off idle that that is the most difficult area to tune for.
At 750 miles it is time to take it out on the freeway for a good run at around 4000...that' still well under it's redline. Try a run with the 106 then another one with the 107. See what feels/sounds/and looks better at the plugs. Adjust needle accordingly. That's not really the midrange yet but it's what you have to work with. Even at 4000 you are probably only at 1/4 throttle at best. Who knows what the correct jet is at half throttle? We are there only for a very short time. maybe just seconds.
I have a theory that the original AMAL specs were arrived at in a cool British climate, damp and at sea level using a fuel that was much different from what we have today. Considering all these variables I am willing to experiment with different carb settings.

In the first post those plugs don't look bad, there is supposed to be a ring of carbon around the rim and the insulators look fair although for perfect mixture you need to be looking down at the bottom of the insulator, a closer shot of the earth electrode would tell more about the timing.

When you read a plug, you look right down inside with a light, to where the porcelain meets the metal. If the mixture is correct, there should be about a 2mm wide black ring down there on the porcelain. If you are using a #7 plug and you have the ignition timing right, the black ring is what remains after the soot has been burned off. It is only an indication as to whether you have the main jets right, so if you rarely use full throttle, it means nothing unless it completely disappears. Getting the needle and needle jets right is easy - all you do is lower the needles until the motor coughs as you change up and down through the gears when riding the bike - then you raise the needles one notch. The primary circuit is usually of little importance unless you have a blocked jet. Then the motor won't open up cleanly from closed throttle.

If there is soot around the rim of the plug, you are probably miles too rich. It doesn't matter much except the motor will be a bit sluggish. Too lean is a real problem because then you can do damage. Getting the black ring on the porcelain is the way of balancing plug heat range, mixture, comp. ratio and ignition timing. As far as you are concerned, comp. ratio and ignition timing are usually fixed variables. You play with the other three. - Make sense ?

Good evening folks , I’m still trying to get my jetting correct , I’ve been fouling plugs because of black soot on the whole of the plug . I’m running m220 pilot 106 needle clip on top position and 31/2 slide , still fouling at theses settings .
Float height is a guess because of correctly getting the angle at which the carbs sit is a guess also. But think I’m not far off with what I’ve set them at.
Next settings will be ( when Amal deliver). M220 pilot 105 needle clip top position and 31/2 slide .
Off the bottom , starting and tick over is perfect , no hesitation at all when setting off .
If theses settings fail I’m going down to A 210 main then vary the pilot and needle position .
It’s all very frustrating !!
Regards
Andy

andy johnson said:

Good evening folks , I’m still trying to get my jetting correct , I’ve been fouling plugs because of black soot on the whole of the plug . I’m running m220 pilot 106 needle clip on top position and 31/2 slide , still fouling at theses settings .
Float height is a guess because of correctly getting the angle at which the carbs sit is a guess also. But think I’m not far off with what I’ve set them at.
Next settings will be ( when Amal deliver). M220 pilot 105 needle clip top position and 31/2 slide .
Off the bottom , starting and tick over is perfect , no hesitation at all when setting off .
If theses settings fail I’m going down to A 210 main then vary the pilot and needle position .
It’s all very frustrating !! Regards Andy

Click to expand...

RE; "I’m running m220 pilot 106 needle clip on top position and 31/2 slide , still fouling at theses settings"
Don't you mean 220 MAIN jet?