Post carb clean tuning?

Surely there's a thread on adjusting mixture screws and idle screw after a carb clean? Rick's famous thread doesn't really cover that part, as far as I can tell.

Cleaned the carbs. The bikes starts up with no choke and no gas, sounds beautiful, but isn't performing 100% (though it's still a very respectable 86%+, I'm sure). I know it could idle lower.

From what I understand, I start it cold, and while it's cold I loosen the mixture screws (in tandem? one at a time? no idea), which will cause the idle to go up. I then tighten the idle screw to push the idle back down to it's lowest comfortable spot. Repeat.

Is this right? I've never done this before. Also, HOW do I get to those mixture screws with the tank on?! Or do I put the tank on a table higher than the bike to the side for this procedure? Or am I missing something all together?

...Or, where's a thread where someone has already answered all these questions? I couldn't seem to find it.

 

Begin with an Accurate Float Height Clear Tube Test and Adjustment.
See Adjust Float Heights.

Remove Idle Adjustment Rod
Wire Brush Threads
Add a loose-fitting Flat Washer to the Idle Rod over the Threads before installing Spring. Lube reinstall. :: Makes Fine-tuniing Adjustment easier. ::
Remove, Lube, Reinstall Sync Screws.
Exercise Sync Screws for later Tuning. Replace binding or stripped screws.

Lube Linkage.
Hold Rack Vertically. Lube Shaft Pivots. Exercise.
Invert 180. Lube opposite Shaft Pivots.

Bench Sync.
Adjust Throttle Plates for synchronous movement.
Open 1, 2 & 4 w Sync Screws
Adjust 3 with Idle Rod.
Set No.-3 to begin.
Use 3X5 Card Strip or Slice of 35mm Negative.
Using IDLE ROD, ... Capture Feeler Material at Bottom of Butterfly Plate to where there is DRAG on the Feeler. Leave feeler in place.
With 2nd Strip --> Match #4 -to- #3.
USE SYNC SCREW to Capture feeler material and set matching drag.
Leave feeler beneath #4.

Set #1 & #2.
Use Sync Screws.
Note:
1 & 2 are Married
After matching 1 & 2 ---> Further adjusting of BOTH will be accomplished by Fine Tuning #2.

PRESET PILOT MIXTURE SCREWS:
::: Initial Preset :::
::: Further Fine-tuning will be needed :::

Install the four Pilot Mixture Screws.
Pre-Set their DEPTH
Measured from the TOP of the Hole to the TOP of the Screw IN he Hole
The Pre-set Measurement is 5/32nds Deep.
Install the Screw. Turn it IN until the TOP of the Screw is 5/32nds below the Flat opening of the Hole.
( 5/32" = 0.1563in. = 3.9688mm)

Install Carbs w/ all Cables, Hoses and Linkages.

:::: BEFORE you bring the Carbs over to the Bike ---> Secure the CABLE Attachment Point to the Horizontal Choke Activating Rod with String, Pipe Cleaner or Plastic Tie. DO NOT jamb the Cable Attachment UNDER THE HEAD, :::

Double-check hook-up for reinstall.
Assure Manifold Clamps not fouling linkage.
Check for Gas.
PRIME Carbs for 35 seconds.

Run Bike.
Set Petcock to ON once Engine is running.

 

from what I've heard from bigfitz52 is that the bike should require a small amount of choke to start from cold. his rational was that the float levels were a tad too high, which then cause the later being an idle slightly too high. I would guess you've checked the float levels but may want to revisit them again. just speaking from experience on my 650 & so I spent like 4 hours or so yesterday trying to get my 550 carbs float levels in a state of "these have to be dead accurate" mode..

just my 2 cents

 

Hmmm... We had a gauge that measured vacuum between all 4 and used that for the bench sync, I guess?

I just want to check the process to dial in the mixture screw settings.

 

A "bench sync" is performed with the carb rack off, on the bench, as a starting point. Hence the term.

Your "running vacuum sync" is done with vacuum gauges or a manometer; with YICS blocked.

"Fine tuning" of the idle mixture screws is nearly the final step, other than going back and re-checking your vac sync afterward.

You don't make ANY mixture or sync screw changes/adjustments with the engine cold; you do all of it once it's warmed up fully.

 

Thank you! That clears up a lot. Those terms all start to mush together when you don't fully understand the whole process, and my comprehension is only about 65% on all of this.

We did block the YICS when doing the running vacuum sync, btw.

How do you get to the mixture screws while they're on the bike, though?! Seems impossible to reach. Anybody have measurements on what screw driver works for this? About to go to the hardware store to get some stuff to get my rack to sit properly that I just got (!!! ), so I can pick it up there probably.

 

XJ4Ever sells a stubby little screwdriver MADE for the purpose that I don't know how I ever lived without.

That being said, either use a "remote fuel source" or prop up the back of the tank for access.

I take it you solved your valve clearance issues.

 

If you're at the point of setting your Pilot mixture screws, you should already have done the running sync, and be warmed up, and have an INITIAL setting of 2 3/4 turns out from lightly seated.

The preferred method is to use a ColorTune plug, but since you're asking the Q, you don't have one.

To set them by ear, you both watch your tach, and listen for a change in exhaust note. Slowly wind #1 Pilot screw in until you both see and hear the cylinder stop firing, write down 1 1/2 for example, then go out until it goes too rich, but not more than 5 full turns. You end up splitting the difference between too lean and too rich, ending up 3/4 turn out from too lean is good.

Next, you drive the bike and do "plug chops" and read the color, writing down the exact Pilot position, and making very small changes until you get a light tan color on the plug. Plan on taking at least an hour.

 

Excellent. Yes, I solved my valve situation. And yeah, so that's the situation... Either take the tank off and use it or another fuel source (mechanic had a gas IV, pretty nifty). Or find the perfect sized screw driver. Remember what the cost was @ XJ4EVER by any chance, fitz?

Time, thanks, that's perfect.

It seems tightening leans the mixture from what you're saying? Which makes sense in my mind, since this screw, as it tightens, starts to close up the main mouth fuel goes through, right?

So from what you're telling me, I tighten it until I kill the cylinder from leanness, and then loosen it until I bog the cylinder down from richness, and then pick a middle ground based on those notes. Then Plug chop to confirm.

Do I do all four before the plug chop phase, and fully experiment and adjust one before moving on to the next?

And if I get lost, to reset, I just tighten the mixture screw down to a lightly seated position, and then back out 2 & 3/4 turns?

Sure would be nice to have that screw driver for the plug-chop phase.

How do ColorTune plugs work? Do they turn blue and green and so on? That's how I've always visualized them, reading about them here. Do you have to take them out to read them like you do normal plugs?

 

You set all four screws before doing a plug chop.

The colortune plug has a glass base so you can see the combustion in the chamber. The color you see is the actual explosion of fuel in the cylinder.

A nice bunsen blue is the correct color, white is lean, orange is rich.

Colortune is the best $55 I've ever spent on a motorcycle.

 

The ColorTune Plug has a transparent ceramic "Window" that allows you to view the COLOR of the burn when the Mixture is ignited by the Spark.

The device enables you to VERY QUICKLY ::: Find ::: the ideal mixture for IDLE.
You actually see the COLOR of the Flame produced by the Mixture as it gets ignited.

Setting the IDLE Mixture to BUNSEN BURNER BLUE places you at an ideal Mixture for the Bike to IDLE, ... and visually confirms you are within the Threshold of Fine Tuning.

When you achieve BLUE; you're close to a TWEAK or two from having the Mixture be just right.

The Ideal Mixture will likely be at the RICH-end of Blue --> PLUS, ... Enough additional RICHNESS to sustain Combustion(s) during the brief transition from IDLE -to- OFF Idle.

The Supplemental Richness insures that the Brief Inrush of AIR preceding the FUEL supplied be Main Jetting has enough Fuel to sustain ignitions until the Main FUEL Supply reaches the Combustion Chamber.

 

Wow. That's cool.

As far as my bike starting without choke, and that not being ideal, that makes sense--My idle is smooth when starting with no choke, but once the bike has warmed up the idle is way too high, around 3k.

Is that mixture screwdriver xj4ever sells an off-set screwdriver?

 

Always set your idle after 30 mins of so of riding at speed. (Full operating temp.)

 

Whether you oun a ColorTune plug or not (I do) your FINAL tune-up is a blend of "seat-of-the-pants" performance, off-idle, AND plug color.

Writing everything down as you tune-up in this final phase helps keep you from getting lost.

I even add some richness during the "winter" in February.

 

Len says the screwdriver is discontinued, for reference. A small stubby screwdriver shimmed down to fit snug works almost as good, he says.

 

Further reference: I used a drill bit by itself--just the bit. I HAVE cleaned out the passage and the screw, so they turn will little enough torque that it isn't that bad--except for the initial 12 turns or so you have to do to sync everything up, of course. Would have been nice to have just an inch of length on it, could have fabbed something up easy enough, but I just made do.

I was going to use TimeToRide's method described, but I realized I wasn't sure what I had read because I didn't have the laptop next to me--I didn't realize I couldn't tell when a cylinder would be killed--I even pushed one all the way in to check, I didn't pick up on it--and so just tuned it by spark plugs from the beginning, made some turns, turn on bike, rev up a few times, then hold steady at 4k for a while, then accelerate (all in place, in neutral on center stand) to 6k and 'plug chop', pulled plugs, made some guesses on tweaks, repeat.

Only got to do the whole thing twice before I had to clean up and head back for dinner with the girlfriend, but then my battery went bad--hadn't changed it since the PO, knew it was due. So then I had to borrow a friend's bike who lived down the road--bicycle, that is, he wasn't home--and bike to autozone, buy a new one, pour in the acid, bump-start it, ride home on higher-than-normal revs to get the battery going, got home, charged battery on 750mAh charger for an hour, and realized...

I lost my side cover. Hoped it was just left at friends--I had replaced on spark plug and pulled it to check clearance.

So I drove back to friend's, drove TERRIBLE. AWFUL. Wouldn't pull out of third gear. Thought, "did I foul plugs right off the bat or something?!".

Get to friend's. No side cover. Heartbreak.

Realize... Two of my spark plugs are off? I had pulled them at the apartment when I pulled the battery to charge, must have forgotten to put them on... This thing managed that whole way on two cylinders, two up, in third. Impressive, actually.

I didn't notice that until I had leaned all four by one half turn, and had put it all back together. So I put I turned it on--sounds like a rocket! Throttle response better than ever! Felt so good, finally back to its old self since before the carb clean, and then finally the improvement of the carb clean. Holy cow.

Anyways, I'll post picture of my plugs tomorrow. I just bought new spark plugs for all four, hadn't put them in since the PO, went ahead and bought them with the battery, wanted a better template for tuning since these looked pretty weathered.

Still pretty sad about the side cover. Rode home same way I rode before, hoping to see it on the side of the highway. No luck.

 

So my cylinder with the broken float pillar was black everywhere except one little white spot. All my other new spark plugs were completely white. I richened those 3 and leaned out the the broken float pillar one by a quarter turn each. Went for a 30 mile drive. Checked plugs. damaged carb is completely black, others are still bone white. Turned damaged carb half turn leaner, one other plug half turn richer (just in a parking lot, didn't want to take off the gas tank to get to the other two). Drove another 20 miles in hot traffic. Still black and white.

So I just turned those two again, half leaner and half richer each, bike is parked right now. Will check again after I leave here in a couple hours and ride back home.

It's slow going, but is this a valid way to tune? Once I find a decent setting for my outer lean plug, I'll set the others at that one and work with them from there. I'm getting good at taking the tank off and putting it back together in a hurry, ha.

Bike runs pretty well right now regardless.

By the way, ordered new carb body from Len today, waiting on that. It's the #4. Just noticed he recommends putting new throttle shaft seals, some kind of V seal... Is it possible to reuse the seal from my broken carb? How hard is that part to find/how proprietary or generic is that part?

Also, how hard is this process of taking the carb totally apart, like taking the butterfly valve and all apart, and putting the pieces into the new body? One friend acted like it was a very involved process, made me kind of nervous. Surely it can't be that much worse than taking the carbs apart in general?

I plan on splitting the rack next time I take them off to soak each one this time, are they that bad to put back together? It's a bit unorthodox, but I have a friend that had a '95 ninja he had sitting for over 10 years we pulled out of storage and got running last weekend--he took his carbs apart, broke his rack (didn't seem bad at all...), and put each carb (all rubber off, of course) in an 'ultrasonic cleaner' that he has for gun parts. I was a huge skeptic, sure it wouldn't be able to get varnish...

...boy was I wrong. The carbs came out looking freaking brand new. His carbs were BAD too, before we put them in. As in sludge made the butterfly valve INOPERABLE, wouldn't budge with light hammering on the valve itself. After the ultrasonic, you could flip them with the lightest touch of a finger. Bike roared to life once we put it together, seems to be doing really well. I'll be doing that to my carbs when I pull them next to install the new carb body.

Comments, advice on any/all of this?

 

get the throttle shaft seals if you're this far into it. after an ultrasonic cleaning with new throttle shaft seals, you'll be looking at a nice shiny 'aftermarket' set of carbs. besides, you'll be breaking it apart like you said so why not get some 'cheap-insurance' and replace 'em? only makes sense to me

i did replace my throttle shaft seals on the hitachi rack and YES it is time-consuming and can be a hassle if not re-assembled properly. trust me from my experience. take your time and be certain everything is back in place correctly then the work is worth the reward. a lot of people recommend not to go this far into "rebuilding" the carbs but if your plan was to split the rack anyways for a good soaking then you would be a fool not to get new seals

consider your plan of attack before deciding what it is you really need and what you what it is you would really like to have. after all, its your decision and we're here for advice & assistance

**EDIT** just read your story about the sidecover and battery taking a dump on ya. boy all that happening to me in one day surely would of pissed me off. hang in there.

also, before deciding to split the carb rack I would definitely recommend at least checking for air leaks (butane method). Unless the carb rack is fully covered in snot & boogers inside and out and you do have an air leak, it might be worth just holding off to do the ultrasonic cleaning. cause if you do go that far, obviously you should just get the throttle shaft seals.

 

PM member -- shmuchaholic -- (SP?)
Have him give you the Link to his Overhaul Pictorial.

When I "Split the Rack" for Shaft Seal Overhaul; I take the Rack to a separate area where the sight of the previously removed parts don't distract me.

It's like "Phase-2"

A well lighted and comfortable work area.
Sketch Pad / Notebook
Plastic Ice Cube Trays (X4 -- Screws, Springs and Parts organizers)

A White Pillow Case draped over a folded Beach Towel.
If you drop something it doesn't bounce or roll away.

 

Fintip, that "screwdriver" that Len said was discontinued. It's about an inch long with a knob on top to help with the adjustment. It is very similar in size to those "quick release screwdriver bits" I found one of those bits that fit the mixture screw nicely, and used the bit by itself. Use the sides of the bit to count 1/6th turns of the screw.

 

So Len said this in regards to any seals I might need:

So I replaced the float bowl gaskets two weeks ago, that's done.

I also replaced the tiny O-rings (mixture screw I guess?) last time I had them apart.

Float valve needle assembly... What's that? I don't think I need it, since my carbs all seemed fine outside of that broken float pillar.

$45... That's so much for some little pieces of rubber. Maddening, things like that. Looking forward to when 3D printers become popular, these old bikes are going to be a lot easier to maintain.

I'll ask for that pictorial, Rick, thanks for the tip.

---

ANYWAYS, tuning woes. Someone help me figure this out... I've been stopping all day, every 15-30 miles of driving or so, checking the spark plugs on #1 and #4, and then adjusting those mixtures. (#4 is the carb with broken float pillar, so that float level is almost certainly off, and seems to want to run a lot richer than the others.)

I've got both down to within an 1/8th of a turn, and on one side of the turn it's bone white, on the other it's ALMOST completely black, with a little spot of white. Brown is nowhere to be found. These are brand new spark plugs, to make tuning easier and because hey, it can't hurt.

What the heck is going on? Does this mean the float level is wrong on both? I didn't adjust float level, my mechanic eyeballed them and we were rushing through, and said they looked fair; the bike had been running well (though lean) before hand, also, and throttle response had been good, so I hadn't adjusted that. Or does this mean I have some air leak some where?

Another possibility I was considering--could it mean my yics passages are clogged, so the swirl isn't occurring, so one side is burning and the rest isn't?

MOELLEAR: Thing is, I'm planning on an 8,000 miles trip to Costa Rica and back, so I really want to get the thing absolutely solid. The thing that's really kicking my ass is those head boots--mine looked cracked, but seem to be holding seal, but I'm sure they won't take much more abuse. I know I should get them, but I just can't deal with $200 more on top of everything else. I might just bite the bullet, but I'm kind of intent on at least trying to recondition them.

Speaking of which: Any one have ideas on that? How does something like a high-heat duct tape work over them? Silicon spray? Melting rubber onto the cracks? Anyone tried stuff like this?

 

Operating with a known Broken Float Pillar precludes any fine tuning adjustments.

Simple as that.

 

what carb body is broke? you don't really want to take off to god knows where with a broken float pillar. if your fix lets go that cylinder is going to quit.
my intakes don't leak but i'am going to try this stuff just to see how it looks, it seals radiator hoses so the intakes should be no problem

 

Polock: I'll be replacing the carb body, and it's just sitting in place right now. New carb body from chacal is on the way. #4 is the broke one. Also, can you let us know how that tape works? Sounds good to me, for sure.

Rick, that makes sense for #4, but what about #1?

Also, if I have to pick, I guess it's better to run them black than white?

I just don't understand why I can't get a tan color, why it's just black or white.

Just to restate:

How hard is it to completely disassemble a carb body and put all its pieces into a new one? Any pitfalls I should be looking out for? (#4 carb)

 

Also, had a thought: I just did a really good vacuum sync, and my settings will be lost when I take the carbs apart; should I count turns on my sync screws, or measure with a micrometer how deep it is in there, or something, to keep those settings? (Got to use vacuum gauges and a proper YICS tool that I no longer have access to.)

 

They're two different things...

Sync screws (3) are on the linkage; mixture screws (4) are the ones buried in the tops of the carbs.

Leave the mixture screws alone; you're going to clobber the sync as soon as you break the rack.

You'll have to go through the whole process again anyway, since any bad throttle shaft seals would have thrown off your ColorTuning (mixtures.)

 

If your Plugs are so Dark they are close to Fouling, ... ypu have to:

Verify you are running the RIGHT SIZE Jets.
Verify you have the Right Size Jets in the CORRECT Position.

The JET Size is Stamped on every Jet.
Verify the JETs you have are the correct ones for that Bike.
And,, that the Stock Jets haven't been "Drilled".

AIR Leaks would contribute to the Lean Condition.
But, severe Air Leaks would make the Engine race and not be able to IDLE very well.

Black Plugs does not always mean the Mixtures are to blame.
Burning Oil will blacken a Plug, too.

 

I'm talking about the sync screws, not the mixture screws; I realize they are two different things. I thought all that was being measured for those numbers was basically compression numbers on the cylinders, more or less, and so the measurements would still be valid--the vacuum measurement is post-carb, and then you adjust the carb to match. I know I'll be taking them out, but I want to put them back just the way I got them, since I don't have tools to sync them like I did before, and I would like to avoid that whole 'index card' business...

So my point is, if I measure how compressed the springs on the sync screws are, can't I just in theory set it back to its setting?

The mixture screws will certainly need to be redone after I am finished--float level will be properly adjusted, and they'll be cleaner.

I have finally found as happy a medium as I am going to get until I re-break the rack and do a real carb clean and replace the broken carb body--all my plugs are partially-black/partially-white. I know it's not oil, because adjustments on the mixture screw make them black or white.

By the way, except for the #4 carb that has the broken float pillar, all the others require just shy of 5 turns to reach this state--as in 4.75 turns gets them bone white, but just a bit more gets them half-black/half white. (5 gets them solid black). Not good numbers there, no? I've read 5 is the absolute max...

And I guess taking a carb down to its constituent parts isn't that bad, since no one is being reminded of horror stories?

 

The Pilot Mixture Screw regulates AIR.
There is a point where the AIR begins to flow; and a point where the orifice is wide open.

As the AIR is allowed to be drawn into the Engine, ... the AIR SIPHONS Fuel from the Pilot Jet supply ... because the Fuel Passage intersects letting the Pilot FUEL Supply to be drawn into the AIR STREAM.

The Pilot Mixture Screw determines RATE.
The Pilot FUEL Jet Size, ... and
The Pilot AIR Jet Size ...
Determine RATIO.

If the JETS are Clean and the Passages are Clean ...
For more FUEL to alleviate a Lean Condition beyond 4-1/2 Turns Out
You need MORE Fuel!
To INCREASE the FUEL Ratio ...

Up the SIZE of the Pilot FUEL Jet.
Assure you have the correct Pilot AIR Jet.