1967 N15: spark plugs very very full of soot

[pierodn]

You don’t just set pilot mixture screws to a turn and a half out and leave them.

You adjust them for correct mixture at idle. Am I being too obvious?

Hi.
Idle works fine 1000 rpm with air pilot 1. 1/2 unscrewed and RPM on the stand go up and down quick without hesitate.
Strange is that now only the left spark has soot.
Can i go from cut 2 sliders to cut 3 or is it irrelevant?.
Piero

 

[texasSlick]

Piero

I want you to turn left pilot air screw out to 2 1/2 or even 3 turns. This may not be good for idle, but if there is less soot, then we conclude idle circuit has a fault. if no change in soot, then we look somewhere else, and return idle air screw to 1 1/2 turns, until idle is properly adjusted as Triton Thrasher alludes.

The slide cut away is not likely to be relevant.

This problem reminds me of another thread, which, if my memory is correct, was posted by you. In that other thread, one cylinder was not firing. After 2 pages of replies suggesting what ignition tests to make, I suggested your mixture was so rich on that cylinder, it could not burn. Another member then suggested to check your pilot jet, and you found it missing!

This problem seems very similar, but not as severe.

Report back with soot test after opening pilot air screw.

Slick

 

[Triton Thrasher]

There is a time to stop arguing with helpful advisors like Mr Slick and do what they say.

 

[pierodn]

Piero

I want you to turn left pilot air screw out to 2 1/2 or even 3 turns. This may not be good for idle, but if there is less soot, then we conclude idle circuit has a fault. if no change in soot, then we look somewhere else, and return idle air screw to 1 1/2 turns, until idle is properly adjusted as Triton Thrasher alludes.

The slide cut away is not likely to be relevant.

This problem reminds me of another thread, which, if my memory is correct, was posted by you. In that other thread, one cylinder was not firing. After 2 pages of replies suggesting what ignition tests to make, I suggested your mixture was so rich on that cylinder, it could not burn. Another member then suggested to check your pilot jet, and you found it missing!

This problem seems very similar, but not as severe.

Report back with soot test after opening pilot air screw.

Slick

Hi.
Pilot jets 25 new.
I will let younknow on monday.
Piero

 

[pierodn]

H

There is a time to stop arguing with helpful advisors like Mr Slick and do what they say.

There is a time to stop arguing with helpful advisors like Mr Slick and do what they say.

Hi.
Idle is fine.
What it mean?
May be better to replace the left carb?
Thank you
Piero

 

[pierodn]

Hi.
Forget to say that the bike has the air filter internal element of steel gauze.
Can it cause a lean air mixture?.
Thank you.
Piero

 

[texasSlick]

Hi.
Forget to say that the bike has the air filter internal element of steel gauze.
Can it cause a lean air mixture?.
Thank you.
Piero

My Norton Owners Manual states:

Amal 930

Main Jet
with air cleaner 220 (Atlas), 260 (650 SS)
without air cleaner 240 (Atlas), 280 (650 SS)

Pilot Jet 25

Throttle Slide 3

Needle Jet 107

Needle Position Central notch

An air cleaner tends to richen the mixture.

Piero, your problem is a rich mixture on the left cylinder.

Slick

 

[pierodn]

My Norton Owners Manual states:

Amal 930

Main Jet
with air cleaner 220 (Atlas), 260 (650 SS)
without air cleaner 240 (Atlas), 280 (650 SS)

Pilot Jet 25

Throttle Slide 3

Needle Jet 107

Needle Position Central notch

An air cleaner tends to richen the mixture.

Piero, your problem is a rich mixture on the left cylinder.

Slick

Hi.
I know this.
But i dont know why!.

 

[Bernhard]

Piero

This problem reminds me of another thread, which, if my memory is correct, was posted by you. In that other thread, one cylinder was not firing. After 2 pages of replies suggesting what ignition tests to make, I suggested your mixture was so rich on that cylinder, it could not burn. Another member then suggested to check your pilot jet, and you found it missing!
Slick

Yes they do drop out if not tightened, even.
I would stop fluffing about and obtain a second-hand Gunson Colortune 14mm Kit Colortune Spark Plug Carburettor Mixture Tool and Here's a trick-use this only at night on a warm engine

 

[pierodn]

Hi.
The left spark plug go on with soot.
But the left exhaust when i close the throttle makes “mumble mumble” with high sound.
Why?
Air from exhaust or what?.
Could be this the problem of such soot?.
Thank you.
Piero