pilot screw questions

I had all my pilot screws turned out to 2.5 and all but one were fouling. So, I turned them all (except the one that wasn't fouling) in to 2 turns. Should be leaner, correct?

All are still fouled, badly except the one that wasn't fouling. Should I set them to 1.5 turns?

Thanks!

 

In will lean it more. I don't have a link but Rick posted a great explanation of tuning by ear recently. It won't hurt but once you get closer thing in degrees not 1/4 or 1/5 turns.

 

Madmax if you find that post let me know
Shaun

 

Are you burning oil?

 

I don't think so. No plumes of smoke from the pipes. Would burning oil cause sooty black plugs? (not oily, just sooty) I thought for sure after turning them in they would be leaner.

 

Since it's my Birthday ...
And somebody is looking for an Old Post ...
And, because I don't feel like typing much tonight ...
Here's a Cut and Paste Job from personal archived notes.

The Art of Fine Tuning "By Ear"
Before they had Expensive Tools and See-through Spark Plugs ...
You only had your screwdriver and theory.

You felt it.
You learned how to HEAR it.

OK Tweakers: ... here we GO!
This is “Real Old School Tuning”
By “Ear”


Start 2.5 ~ 3 Turns OUT from bottom on all 4 Carbs
For 750 Bikes I’d set them at just between 2-3/4 & 3 … closer to 3
Put two drops of light Oil in each Pilot Mixture Hole'

Important:
Make yourself a screwdriver that fits the slot on the Pilot Mixture Screw with Precision. Even if yours are loose and won’t bind … you want to be able to “Feel” the Screw moving. If they aren’t loose an ill-fitting screwdriver will destroy the slot, causing a big problem!

Above the Starter Motor ... Under Carbs 2 & 3 is the Idle Adjustment Rod.
It has a Thumb Wheel on the end.
You can add a thin washer to the Rod to make it easy to turn.
You’ll need to be able to make highly precise adjustments without difficulty!

Turn it Clockwise a tiny bit at a time until the engine is running steadily.
Don't exceed 1,200 rpm’s (1,050 if you can get it. 950 if the Tuning permits)

While the Engine’s running.
Begin some Tweaking.

Turn the Pilot Mixture Screw for #-1 OUT ... real SLOWLY.
Listen for the RPM's to INCREASE.
The revs should rise as you give it more Fuel and Air at the Pilot Screw. This is Pilot Mixture for Idling.

When the revs rise here’s what to do...
Keep the RPM's at 1,100 by reaching under the Carbs and lowering the Idle Adjustment Knob. Stay close to 1,000 rpm’s at all times.

"Tweak" OUT ... the #-1 Pilot Mixture Screw listening to the Engine and Exhaust note VERY Carefully.

Keep turning the SCREW ~> OUT if the RPM's continue to rise.

At some point ... The RPM's ~~> will NOT continue to rise.
Remember this Point. You have to come back to it.
At THIS point ... MICROSCOPICALLY continue the Turning OUT...

UNTIL <~~

The Mixture gets TOO RICH and the Bike:
Coughs
Misfires
Burps
Runs rough
Etc.

>> STOP <<

THEN <~~ Get ready to make a CRITICAL Adjustment.
Pretend you are about to move THE SECOND HAND on a STOPWATCH!
One FULL Turn would be 60 Seconds ... right?
OK.


Turn that Pilot Screw ~~> IN <~~

Two (2) Seconds ... maybe Three (3) (Degrees, small, a (my-nute amount)
Don't go four.

Run fans to keep the bike cool.
Throttle it up and let it idle.

Adjust the IDLE rpm's with the Idle Adjustment ROD.
1,100 Max

Tweak #-2
Just exactly like #-1

(If the rev's exceed 2,000 ... back-off the IDLE SPEED ROD More)

Then finish-up doing #-3 -&- #-4.

When you are done ... TWEAKING ... you will need to Road Test for THROTTLE RESPONSE.

IF...

You are Idling, say, at a Red Light and when the light turns green and you take-off ... (Getting “Out-of-the-hole”) … and, …

The Bike ~> BACKFIRES a little bit before the Power comes on:
Your LEAN
The Pilot Screws need to be:
Tweaked OUT
Two (2) Degrees.
Chart where you are at from this moment on … +2 Degrees

IF...

You are at the light and take-off...
The Bike ~> HESITATES for the slightest bit before the Power comes on:
Your RICH
The Pilot Screws need to be:
Tweaked IN
Two (2) Degrees. (Almost not turning the screw at all. A nudge!)

Fine-tuning will be complete when you have Tweaked-Out the Backfire or the Hesitation during Further Load Testing.

All further Tweaking is to be done in increments of:

Two Degrees at a time.
Go find a closed Industrial Park and do it all in one sitting.
Have somebody put the tools you need in a sack and follow you over there in the car.
Don’t forget a Flashlight.

Backfire = Lean = OUT

Hesitation = Rich = IN

Go for it!

Get Tweaked
Watch your Plugs and treat each Cylinder individually.
Read the Color of the Plug on the Center Electrode’s Ceramic Collar.
Too Dark (Beyond chocolate brown) Tweak IN: 2-Degrees

Too Clean: (Clean or no coloration) Tweak OUT: 2-Degrees
As you Tweak individual Carbs for the right Mixture … Watch the Plugs coloration at the Center Electrode Ceramic Collar.

Clean: Bad. Lean. Tweak Screw OUT for MORE Fuel.
Although the Bike will run superbly Lean like that … it’s a dangerous condition that can HARM the Bike permanently.

Light Tan: Lean but OK. This is a Power setting. The Mixture is burning Fast making big power. You’ll have fast acceleration with the Plugs a light tan. You must monitor the situation and keep an eye on the Oil Level. If your Oil starts disappearing and you don’t have a leak … you are still too Lean.

Light Brown: Normal

Dark Brown: Rich. Most people like to have them at the Dark Brown Mixture setting. The Engine makes good smooth power and cruises really nicely, staying cooler than the Lean settings.
If I am tuning someone’s bike for them … I set them at Dark Brown so they are insured against Ring and Valve damage.

Have a Happy Summer
Get it running good.
Rick Massey

 

Awesome write up! It's definitely going into my Yama-tome.

Since we're on this subject...

I noticed what appeared to be oil on my plug at one point, but I adjusted the screws, rode it a bit, and the oil was no longer there. (Just black sooty-ness) If by adjusting the screws it has no discernible effect on the rich/lean factor, does that mean I could use new mixture screws? More importantly, if there is oil on my plugs, that's not a good sign either, correct? Piston ring/valve replacement?

The order of the screw (as I recall from bottom up) is o ring, washer, spring then screw, yes?

 

That order is correct.
You could change out the 'o' rings if you have doubts.

 

On many occasions, trying to replace the Pilot Mixture Screw as a UNIT will often cause the O-ring and Flat Waster to "Tumble-off" and switch places.

Check for that.

If you are adjusting the Pilot Mixture Screw and getting NO change ... the most likely fault is the Pilot FUEL Jet is clogged and not allowing Fuel to rise into the Passage

-Or-

The actual Passage is clogged somewhere not allowing AIR to move freely within the Passage.

Remove the FUEL Jet and Probe it with a thin wire tool.
Guarantee it it passing Fuel or replace the Jet.

Flush the Passage using a Rubber Syringe to Make sure the Passage is free flowing.
Flush:
Pilot Fuel Jet Hole upward
Pilot AIR Jet down ans sideways.

Syringe: