Setting the idle mixture WITHOUT a ColorTune

Oh Gurus of the XJ world hear my plea!

How do I get them close without a colortune? :?:
Is there any way?
Or have I been smoking crack again? 8O

As Always
Thanks in Advance,

 

Set the idle down as far as it will go and still idle. Turn the idle mixture screw in #1 until it starts to slow down. Back it out1/2 turn. Go to #2 and do the same thing. Same thing for all carbs.
If the idle speed increases after a carb is set, adjust it back down before doing the next carb.
When you are done, re sync the carbs, and do the routine again. Set the idle back to what ever you like, and ride.
If there is any stutter at roll on, back the screws out a quarter of a turn, and try again. CZ

 

Yes it can be done, it won't be exact but you can make it run good. I have a color tune but don't often use it.
First everything MUST be is order, valves adjusted, carbs clean, no vacuum leaks. No previous problems with fuel mixture like trying to run pod filters or exhaust changes with stock carb jets. Get all that stuff fixed before you try.
My process:
I keep the engine running durring the entire process because it takes a few seconde for a small change in the mixture to become effective. I'll rev the enging several times at each mixture setting.

1 Carbs off- cleaned, bench synced and float levels checked
2 Set idle mixture to factory start point, 2 1/2 turns out for the XJ1100
3 Start engine and warm it up, set idle speed to 1000 to 1100 rpm
4 Vacuum sync carbs
5 readjust idle speed if necessary
6 Give the throttle a quick opening(about 1/2 open) and listen to the engine. It should rev up smooth with no hesitation or stumbling. Look at the exhaust, there might be some black smoke watch for it. If there is just a little you are close , proceed and start closing the mixture screws in the next steps. If the engine seems to backfire through the intake its lean and proceed through the next steps opening the mixture screws.
7 If you get some stumbling, close or open the idle mixture 1/8 to 1/4 turn and try again.
8 Keep trying and closing or opening the mixture screws 1/8 to 1/4 turn each time until you get the best quick opening throttle response. Most XS/XJ1100 I have worked on seen to like the mixture screws between 1 3/4 to 2 1/4 turns.
9 recheck the vacuum sync and idle speed

I have heard of some using a infared thermemeter to check exhaust pipe temps, I have never done it.

 

Becoming a Tweaker.
This is Real: "Old School Tuning”
Fine Tuning By “Ear”

Run Electric Fans to provide Air Cooling during Tuning Process.

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. Oil its threads.
You’ll need to be able to make some highly precise adjustments without difficulty!

Turn the Idle Rod 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 the "By Ear" (and feel) Tweaking.

Turn the Pilot Mixture Screw for #-1 OUT ... real S-L-O-W-L-Y.
LISTEN for the RPM's to INCREASE.
The revs should RISE as you give the Mixture Screw turns out for more Fuel and Air qith the Pilot Screw.
This is finding Pilot Mixture ... for IDLING.

Listen to the Engine very intently.
The rpm’s are about to change.

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 rpm's 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 too far.

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) Seconds.
CHART where EACH Carb is at from this moment on … +2 Seconds
Adding some Richness, ... Zeroing-in on the Sweet Spot.

✔✔✔
"The Sweet Spot" requires you to engage in FINE TUNING.
Not, ... "A Turn"
Not, ... "A Half-a-turn"
Not, ... "A Quarter turn"
Depending on the condition of the Engine, ... The SWEET Spot can Come and Go within a Quarter-turn.

IF...
You are at a light and take-off...
The Bike ~> HESITATES or Boggs Out
For the slightest bit before the Power comes on:
Your RICH
The Pilot Screws need to be:
Tweaked IN
Two (2) Seconds. (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 Seconds 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-Seconds

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

Clean:
Bad. Critically Lean.
Dangerous.
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.

 

There ya go. WHOLE lots easier on a single or a twin; makes you wanna go out and buy a ColorTune, doesn't it.

Good write-up, Rick.

 

Before you even begin, ...

Remove the two, plastic "Beauty Pieces" Covering the front of the Airbox.

Even with those removed, its a tight reach in to get to the Idle Adjustment Rod.
And, ...
Once that baby warms-up, ... a forearm and wrist burning torture chamber that really stings.

I have an old "ACE Bandage" I wrap on my arm before reaching in there.

 

Thanks guys!
Currently I have set the timing and the valve lash and was working on a vacuum sync and I have a problem.
I got the 1-2 carbs synched and the 3-4 carbs done but when I try to do the 2-3 step the rpms are 4000!
And Ideas?

 

WOW!!! I just did this, and with better than expected results! I still have to test drive, sync and tune again...but I'd like to share some thoughts ...

I used a socket extension to listen to the cylinder...honestly I didn't think it would make that much of a difference since I've done that before, but this time I could CLEARLY HEAR going from lean to rich IN THE SPACE OF AN 1/8TH TURN!!!! My plugs don't seem to change color, I'm pretty sure it's the gas type here in SoCal. I've been running super rich trying to get my plugs darker...I just gave up on that.

Also, I ended up with the screws about 2 and 7/8ths out.

It helps a LOT when the idle is as low as you can possibly sustain. I think that there's little room for a less than ideal mixture when all the mixture is coming through the pilot jet.

I couldn't help but wonder if this would be best done after a bench sync but before a full sync....so that the butterfly's are as even as possible, ensuring that the air/fuel mixture is influenced nearly only the pilot jet.

 

The weird high idle was caused by a vacuum leak! 8O
Ya know the screws on the rubber manifolds that you aren't supposed to touch under penalty of death 'cuz if they break off you're screwed?
They were loose!
All. Of. Them.
#3 cylinder was loose enough to break and eat part of the gasket.
The boots were in perfect shape!
New gaskets, snugged up bolts ,a vacuum sync, and set the idle screws and boy does it run!
Smooth from 800 rpm up! 8)
Thanks again guys!

 

If they are loose, ...

Take the time and TREAT them with AntiSeize Compound.

If it was me, ... I'd take every last one of the out and replace them with:

Stainless.
Teflon Wrapped.
Anti-Seize Compound Q-Tipped all over the Head Threads.

 

interesting to note Techlinetom. I'm having an issue with my idle increase over time up to and around 4000rpm. i have taken all 8 of those bolts out and replaced the rubber manifold gaskets. now I'm wondering if I tightened those down tight enough... anyone know what the torque specs should be on them??

 

on a similar note, I have in my possession an '84 vintage EGA (and other tools on the cabinet mount) sniffer.

Is it even worth trying to use without individual exhaust taps?
Even if it's useless for my Seca I was gonna try to use it on a twin (also without taps) by plugging the crossover with a wad of old heat wrap (similar to the cloth strip "YICS tool" ) and sniffing each pipe.

 

So after riding to work this morning (10 minutes at 80 mph) the idle was at 3000 rpm. No problem, it just wasn't warm enough yesterday when I set it....turn it down. Turned it down to what the tach says is 1000 (I'll get back to that) and it does the characteristic "slowly dies", where it just can't get enough energy to keep going. Bump up the idle a little, pay attention to the throttle, get home ok, start to sync and tune.

Clean out YICS, insert (more like stuff) rag soaked in Amsoil 80w90 gear oil, and sync. Didn't have to change a thing (didn't blank the YICS last time, so I really thought that was the problem) Sync's perfect at about 1100- 1300 rpm (the tach just isn't that precise!). Tune by ear with the YICS still blocked....thing idles like a sewing machine at 950.....awesome...or so I think.

Reinstate the YICS....slowly dies. ugh. So I continue tuning. Have to pull the screws out a half turn just to play. Turn the idle down, tune, turn the idle down, tune, etc. until it will idle at 950 (or so the tach says) and any change in or out of the pilot screw on any cylinder will mess that up.

Question #1: The idle seems REALLY slow...I know it says about 1k, but it's gotta be more like 5-600. I come across other Yamaha bikes and if I match their idle, I'm running at more like 1200-1500 rpm according to my tach. Is there any way to confirm the idle other than my tach? It just doesn't seem be that accurate at that rpm!!

Question #2: The idle is really lopey, like sometimes a stroke is more powerful than another, but at anything above 1100 it's quite smooth, and I couldn't tune it out....is that due to the low engine speed, did I lose my sync somehow, or lack of using a colortune to do it right?