Idle Frustrations

r u snapping the throttle after each carb adjustment.

cuz if you just adjust and leave it alone. the sync isn't getting done properly.

i did my ninja 5 times before i tried that method. adjust. throttle snap. adjust. throttle snap again.

before i was just adjusting. and calling it good. but the idle never worked right. by snapping the throttle you can see the sync go out again. usually takes a couple of adjustments before you can snap the throttle and have it come back to sync. then you've got a perfect sync.

now, i make adjustment and do throttle snap after each adjustment. no problems since.

perfect idle every time.

 

Thanks as always for the advice and idea's...I've gone over the bike I don't think its a air leak..so I will go after the valves and see where things are at...makes the most logically sense to me as I'm sure its not been done..have no history on the bike, but still nothing else has shown signs of being touched so I'll go that route then see where things lead me.

 

Post results after you check them for discussions sake.

Keep in mind that you will need to do a vacuum sync afterward.

 

As promised my follow up.

Valve adjustment turned up to have one intake with zero clerence and an exhaust well out as well...so popped the shims went down to the yama dealer and they were happy to do a swap...btw without a swap they were 25 each!.

So that all went well...bike ran bettter but still have my problems, so it was back to the bench with the carbs..thought about it and only float levels were to be rechecked...low and behold I found my problem.

Technique is often a factor in working on thing I find and this is what bit me in the butt more than once. When I was setting and checking I would turn on the fuel to fill the bowls then when I saw the flow stop I would shut down the flow....wow big big mistake.

What I figured out is the bowls will fill and stop..then after waiting about 30 seconds they would settle and take a little more in...so I was getting false readings.

In the end I learned just how damn hard it is to get these set right on spec...took about 12 tries per carb...must be me and my big ham hands the just kept going over
then under, but patience and a gallon of fuel won out and the bike ran like a dream...sync perfect..all blue on the colortune...nice idle and great response!

So this morning I got up to find fuel dripping out...not sure what's up but I am using the kickstand not the center so maybe one isn't perfect..not sure what's up but
know I've still got something wrong!!! This machine has pushed my limits with being so particular...but I will find out what's going on and resolve it.

 

No leak when the selector on normal...not sure whats up with this. bike won't leak when level guess I just need to keep the petcok set to norm and it should be fine..going to see if the crank got fillted up just in case its levels still bitting me.

 

Sounds like one or more float needles don't like to work properly when the bike is on the sidestand, or you have a float binding.

With your fuel lever set to "ON" there should be no (new) fuel flow when the motor isn't running, just what's in the bowls.

 

From what you are saying, I understand that with the selector in the run position there is no leak. The selector has three positions, Run where fuel flows when the engine is running due to vacuum, Reserve for when you run low, and prime. The only time you need to prime is in the event the tank was empty or you drained the carbs. If there is no leak in the run position, no problem. The only time I ever change the position is when I run low on fuel.

 

I FEEL your pain BRO. I have countless hours on my buddies, xj700x
I had to replace one carb (float stand broken) and repair the 2 outside carbs bodies . the were dropped or something and small pieces were broken causing air leaks due to shaft seals to be exposed..that was and easy repair part of it.
i pulled all the butterflies apart and replaced all the o rings. Thanks Mike for the carb body, screws, and O rings. there will be a a little something special in your X Mas stocking this year. ;-}.
after all this I put the rack back in the bike. it fired right up! I re synced the carbs and #%())%%#@! same problem. won't Idle when warm #&^%)%&!!!!
the only saving grace here is that i have determined by reading posts that it is "The Valve's" that are the cause of all this.
Now I'm gonna load the bike on a trailer and take it back to buddy with the names and #'s of 2 good local mech's who he can Pay! to adjust the valves.
thanks for all the help
LB

 

Two things I've found that might help.

1, polish the float pins just as you would the throttle body's on
the carbs. Makes a world of diff in how the float valve operates.

2, on m 700, once tuned you only need to barely turn the idle adj
screw to make a change. Just like Rick suggests wih the pilot screws.
Very small change in settings is all thats needed most of the time.

 

Once you have the Pilot Mixture Screw close to where it needs to be for Ideal Idle and Off-Idle Tuning, ... Further adjustments to Precisely FINE-TUNE the Pilot Mixture, ...
(From
|<--Too Lean<>Performance Lean<>Normal<>Slight Rich<>Too Rich-->|
Will be a matter of Adjusting the Pilot Mixture Screw VERY SLIGHTLY.

Picture the Sweep Hand on a Stop Watch.
One Revolution - One Turn = 60 Seconds.

Once you get the Pilot Mixture Optimally Set, ... the further adjustment to Perfectly Tuned will involve moving the Mixture Screw within 0 -to- 10 seconds.
(That's less than the Width of 2-Dimes)

<><><><><><><><>

ColorTuning:

The IDEAL Color for having the Bike IDLE is:
Bunsen Burner Blue.

Bunsen Burner Blue --> IS NOT the IDEAL MIXTURE for Tuning.

The Blue is an Ideal Air~Fuel Ratio for Idle.
You NEED the IDLE MIXTURE slightly RICH.

You have to make the Idle Mixture Rich enough to support the INSTANT that you move the Throttles ==>> OFF IDLE.

When you Transition from IDLE to OFF IDLE. (i.e. Getting out of the hole.)
You NEED "Supplementary Richness"
Enough to SUSTAIN COMBUSTION for the RUSH of Intake AIR that will NEED Fuel which precedes the MAIN Jet Supply.

The DURATION is Short.
6 -or- 8 "Rapid-Eye-Blinks"

Too Lean and you Hesitate.
Too Rich and you'll Bogg-Out.

 

Rick, would you mind expanding on this topic, I respect your opinion and insight.

I had a bit more time with the bike now, I do notice some slight hesitation and not everytime, I'm use to working with fuel injection bikes and carbs on my old cars, its almost like I'm really close but still I know it can be better.

I've noticed the hesitation primarily after a longer idle time...kind of feels more like loading up....couple of blips seems to clear and then I don't notice it..but still wondering about that perfect tune.

So at idle I was at blue with 2.5 turns, so I turned out till I saw a bit of orange...then backed off until she went blue. Just seems right to me that way...but I'm still learning after all these years.

Rick your talking about the transitional tune...so I'd like to hear more on how your going about that part...if you wouldnt mind sir.

 

Oh and yes no leaks at all when in the normal run position, so that's all good. I am happy to report she's all clear...started doing some cutting yesterday...so at least now I can move on to body and paint. as I continue working towards a completed project.

Thanks again for everyone's input. Hey and for the record...do your own valve adjustment...its way easier than getting the carbs right....and it took the popping I had right out. Just think what a zero clearance valve is doing, its a short amount of time that not only needs to be done, but could save you a bunch of money...the only thing I paid for was the tool..the rest was just time...and not that much of that.

 

The Pilot Mixture Screw.

The Pilot Mixture Screw is an AIR Metering Needle jet.
When AIR flows into the Carb, Metered by that Screw, it brings-along FUEL, ... because the Passages meet.

The Pilot Mixture. AIR and FUEL enter the Carb from inside the Throttle Plate.
The Factory Pre-set for these AIR Screws was 2.5 turns Out.
The 2.5 Turns satisfied California EPA, where the Bikes came ashore.
Most dealers added, ... just short of another 1/4 Turn and Re-plugged them.

The YAHAHA EGA Machines, made to aid Fine Tuning, broke-down and the process was done, ... "By EAR"
Still in use.
By those places that WILL service the Bike.

Find the Fastest Idle using the least Throttles or none.
Let the Idle rise as the SCREW is turned OUT
Continue until the Idle NO LONGER quickens.
+> This Point is IDLE.
>>(||)<< IDLE
Remember this spot.
Continue until the Cylinder BEGINS to MISS because the Mixture is too Rich.
>>(|| + X = Miss)<<

Turn IN -- 1/2 the distance between (||) and (||X) = Pre-set.

Fine Tune as needed depending upon Plug Color for Individual Cylinders.

Along comes ColorTune to help find the Sweet Spot.

Coloortune finds IDLE (||) ... Right on the nose.
IDLE!

You need to TUNE for what happens at the INSTANT the Bike is TRANSITIONED.

From IDLE -to- GO.

If you ColorTune ... BLUE.
You get enough Gas in the Air to let the Bike IDLE.
Not enough to GO.

The surge of fresh air brought-in at the INSTANT the Throttles Open needs that extra bit of Fuel.

 

Thanks Rick, I think you confirmed my setup technique and now I have no complaints about the response...its as snappy as could be. Thanks for sharing the info and insights.

Now off to beat a fender into submission

 

I'm awaiting my colortune plug from Len now. This information will be very helpful. Thanks for the insight.

 

Hey Rick; the BLUE you mention, is it by any chance the BUNSEN BLUE people seem to be so hung up in?

N'er mind, I just read page two and noticed we're indeed talking about Bunsen Blue....