lean mixture, jetting carbs, and other problems

After seeing a few threads about spark plug color and what it could mean for your engine, I removed my plugs and now I'm worried that my bike is running way too lean:



Initially I had my cousin clean the carbs (an MMI student, so I trusted his work) and I had a local shop sync the carbs. Also, the carbs haven't been jetted for my supertrapp 4-1 exhaust yet.

So how do I add more fuel to the mix? Of course I'll have to jet the carbs, but I'm guessing there is more I will need to do. I have a service manual, but it doesn't say much about this.

 

Re: lean mixture, jetting carbs

Before jumping into re-jetting, pick up a colortune plug and try adjusting the mixture using the mixture screws. If you cant get the mixture within range with this method, then at least the colortune plug will come in handy when you do start re-jetting - you need to be able to verify your mixture at different rpm and throttle settings - the colortune manual will help with this. Good Luck.

 

Re: lean mixture, jetting carbs

I agree. Looks way lean to me too.

Look in the XJ4Ever forum, chacal has a whole "chart" of basic starting points for rejetting based on what mod has been done to the intake/exhaust system.

You can add a bit more fuel to the PILOT mixture via the pilot mixture screws on top of each carb; but from the sound of it you'll need to re-jet. The 750 Seca originally had a collector-box based system that would have flowed vastly differently from the 4-1, no matter how many discs you add/subtract from the Trapp.

Is the intake system stock or has it been modded somehow as well?

 

Re: lean mixture, jetting carbs

Thanks for the suggestions (and fast replies!), I'll check out the colortune plug.

Just for reference, this is the pilot mixture screw, right?



Also, if you look at the carb-to-engine intake boot there are what appears to be a few cracks on it. Can this cause a problem? I was told that I could test for air leaks on this part by spraying some starter spray on the cracks and seeing if the engine reacts to it. I tried this but the engine rpm did not increase, so I assume it's OK? If not, could I simply tape up the cracked area? I looked up replacement intake boots and they are not cheap...

Intake is all stock.

 

Re: lean mixture, jetting carbs

That is the pilot mixture screw, one on carb, yes. There are four, one on each carb. A quarter of a turn is a MAJOR adjustment, so go easy, and keep track of what you're doing/have done as far as changes.

Those cracks in the intake boots often do not go all the way through. Both of my 550s manifolds appear to be horribly cracked; the cracks don't even go halfway through.

They should be attended to in some fashion; I flushed mine out really well and packed them with black adhesive RTV. You can also paint them with Liquid Electrical Tape; or "sleeve" them with sections of bicycle inner tube.

The best way to check the cracks is with the carbs off, then you can hook a finger into the boots and flex them from the inside.

Since your prelimnary vacuum leak test showed NO results, along with the fact that the plugs are uniformly white and the bike doesn't have surging idle/racing problems, I'm more inclined to think you're running lean rather than fighting a vacuum leak.

Adjusting the pilots is fine for lower rpm, and off-throttle running; but when you get it up over 6 Grand, it's on the mains and tweaking the pilot screws won't matter anymore. That's when you need bigger main jets, or to at least raise the needles.

Since you didn't go and read the article in chacal's catalog, here're the guidelines:

MAIN FUEL JET SIZE CHANGES NEEDED PER TYPICAL MODIFICATION:

Typical Exhaust Changes:

+2 main fuel jet size for custom 4-into-2 exhaust

or

+4 main fuel jet sizes for 4-into-1 exhaust

or

+4 main jet sizes for no muffler (open headers)


Typical Intake Changes:

+2 main fuel jet sizes for single K&N filter (inside a stock airbox)

or

+2 main fuel jet size for drilling holes in the airbox with stock filter

or

+4 main fuel jet sizes for individual pod filters (no airbox)


Additional changes:

- Add up all the main fuel jet size increases and subtract 2 sizes.

- Decrease main fuel jet size by 2 sizes per every 2000' above sea level.

- Under a mis-match condition, such as when using pod filters with a 100% stock exhaust, or 4-into-1 header with stock filter and air box, then subtract 2 main fuel jet sizes.


PILOT FUEL JET SIZES CHANGES NEEDED PER TYPICAL MODIFICATION:

Pilot fuel jet size changes are related only to the change in main fuel jet sizes according to the main fuel jet size formula described above. Note that this pilot fuel jet rule is for the main fuel jet size change BEFORE any main fuel jet altitude compensation is factored in:

Increase the pilot fuel jet size +1 for every +3 main fuel jet size increases.

Additional changes:

- Decrease pilot fuel jet size by 1 for every 6000' above sea level.


PRECAUTIONS:

- Make sure your carbs are in perfect working order before making jet changes....meaning fully cleaned internally and rebuilt, operating properly in their stock configuration, proper sized air jets and needles, etc. Otherwise, you'll like find that all of your efforts are going to be a HUGE waste of time.

- Check plug color often and adjust as needed, 2 main fuel jet sizes at a time and 1 pilot fuel jet size at a time. Bright white plug insulators are a sign of an overly lean fuel mixture condition and WILL cause damage to your engine over time, up to and including engine seizure!

- Synch the carbs after each jet change.

- Make sure the floats are set correctly

- Seriously consider purchasing a Colortune Plug Tuning kit.

- You may find it necessary to make changes to the size or shimming of the main jet needle. There are no guidelines on what or how to do these changes, this is true trial-and-error tuning!

To which I will add: Quit running it the way you are before you hurt it.

 

Re: lean mixture, jetting carbs

Thanks for re-posting the info, but I'm slightly confused about what jet size I should get.

According to the guidelines, I should add +4 to the main fuel jets for the 4-1 exhaust, but then -2 from the total and another -2 for a mismatch (4-1 w/ stock intake) leaves me where I started concerning jet size.

If I have to jet, perhaps I should start with +2 size main fuel jets anyway?

 

Re: lean mixture, jetting carbs

I would. And probably go "up" one size on the fuel pilot too.

 

Re: lean mixture, jetting carbs

Ok, just got my new jets & colortune from chacal and I'm about to pull off the carbs.

The service manual I have has a nice exploded view of the carbs, so it should be as simple as swapping out the jets (right?). I was going to jet the carbs first then adjust with colortune.

When I get the carbs off, is there anything else I should check them for? They work fine now, aside from running lean, but perhaps there is some kind of periodic maintenance for the carbs that I am forgetting to do.

Also, since I will have easy access to the cam chain tensioner, I would like to ask for advice about my cam chain. When I ride, I can hear it scraping the top of the gasket starting around 5500 rpm. My bike has the auto tensioner, and I have tried the "trick" posted on this forum, but it has not changed anything.

My bike has almost 60k miles on it--perhaps it's time for a new chain? Will I need to replace any of the chain guides in the engine? Most importantly, will I need to take the whole engine apart to replace it? I really want to avoid doing that.

 

Re: lean mixture, jetting carbs

I've finished jetting the carbs and colortuning. While colortuning, I turned the screws out until it was all yellow, then turned them back in until I didn't see any yellow flashes anymore.

Also, I just got back from doing a plug chop today.

First, I rode a lap around my neighborhood to warm it up. I pulled the plugs after I got in the driveway and there were only a few brown spots on the plugs. So I lifted the tank and turned each of the pilot screws out 1/4 turn and set off again.

Next I did the actual plug chop. I rode for about one and a half miles on a local highway, 55mph ~4500 rpm in 5th gear. I flipped the kill switch and coasted to the side of the road. I pulled all the plugs and they were all pure white, no better than the first picture I posted.

So what should I do now? I used the plugs that I've been using all this time for the plug chop. Should I buy new plugs and try again? I'm getting a feeling that there is something else wrong besides jet size. Time to dig into the carbs? Also, I've read on here that Marvel Mystery Oil can help curb the effects of running lean, but does it really make it safe to ride?

 

Re: lean mixture, jetting carbs

some people need to shim the needles up to dial in the mid range. try it. a plug chop at 5500 is not wide open so a main jet increase may help but also end up being too big at WOT.

MMO does nothing but harm. it has less lubricity than the fuel you are putting it into and is actually not going to richen the mixture as much as most people would think its main ingredient is naptha. i would highly recommend 2-stroke oil, it has more lubrication and will add more "fuel" to the mixture.

 

Re: lean mixture, jetting carbs

Update: I've inserted two washers to raise the needles some. The needles are raised about .02" each.

I did another plug chop (rode for about 1.5 miles at 4500rpm 5th gear) and the plug from the 3rd cylinder from the left is now very brown! Unfortunately, the other three are still very white.

Since it is running so lean, I'm not riding the bike so far for these tests, just around my neighborhood to warm it up and then the 1.5 miles for the plug chop. Should I buy new plugs for additional tests, or would I see more of a change if I rode it longer? Since plug 3 changed so much from just this short ride I don't think riding it longer would change the others, but I have to ask anyway.

Anyway, are my carbs out of sync now? Is it unusual to raise the needles different amounts or is there another way to get more fuel into the other cylinders?

Thanks for everyone's help so far!

 

Re: lean mixture, jetting carbs

I'm still trying to solve this problem but I'm not having much luck.

The other day I tried to adjust my float levels, they were all a little low. I set them up level and adjusted them with the clear tube method described here. I put the carbs back on the bike and while it started right up and ran fine it is still very white on three plugs (the other one now black) after a plug chop.

I'm running out of ideas, but I'm beginning to think my carbs aren't as clean as I think they are. I guess I'm going to have to tear them apart and clean them the Right Way soon.

That being said, what kind of cleaning tools would work well for cleaning out all the tiny passages in the carbs? Would something like a gun cleaning kit include all the tools I'd need?

 

Re: lean mixture, jetting carbs

The "Blue" Flame you observe when ColorTuning is NOT the Optimum Setting for RUNNING.
It's the Optimum Setting for IDLE.

You need slightly MORE Richness than Blue.
The Blue is a Beacon that you are in the right vicinity.
Not the Light that indicates you win a prize.

Go to the RICH-end of the Blue.
Add more Richness.
About the width of a Nickel.

 

Re: lean mixture, jetting carbs

I'm beginning to agree. Be careful using drill bits, wires or other "hard" gun-cleaning utensils in the carbs. You don't want to scratch or gouge the insides of any of the tiny holes or passages; I get a lot of mileage out of stiff nylon bristles plucked from a parts-cleaning brush.

 

Re: lean mixture, jetting carbs

It took me a while (too long really), but I finished cleaning my carbs and they are back on the bike now.

To clean the carbs I completely disassembled them and boiled the carb bodies and bowls in lemon juice. I replaced the bowl gaskets, throttle shaft seals, fuel shaft o-rings, idle mixture o-rings, and numerous washers and bolts (should have bought a JIS screwdriver...but they are hex-head bolts now). I polished up all the brass parts as well as I could (WD40 + 800/2000 grit sand paper). I also checked all the little holes in the emulsion tubes, jets, bowls, etc, and they should be clean now.

My carbs pass the "clunk test" and I double-checked my float levels, all are within spec.

I made little marks on the throttle shafts below the adjustment screws to sort of record the adjustment of the throttle plates, so bench syncing wasn't very difficult.

Unfortunately, I forgot to put my battery on a charger during all this, so I'm paying for that mistake with limited testing sessions... I'm lucky the bike even started up after all this time. It took a while, but it did start.

Before I did any adjustments, I let it idle for a few minutes. It idles right at 1000rpm, but it won't idle without the choke, unless I open the throttle just slightly (which also helps it to start).

I actually managed to take an extremely short ride to the end of my street and back. It was extremely weak below ~3.5k rpm, otherwise it seemed ok, but there wasn't much I could gather from such a short ride.

I checked the plugs after my ride and they are all pitch-black now, so I thought it was running very rich. I turned my mixture screws in in hopes of leaning it out a bit.

Since my battery wasn't strong enough to continue, I let it charge overnight.

The next day I adjusted the idle speed screw just enough to let it idle without any choke.

I tried to do some colortuning today, but strangely I had to turn the mixture screws out before I could see any yellow in the cylinder, so that's left me a bit confused. But I adjusted the screws anyway to get the right color (right before yellow).

I will be picking up some new plugs soon (NGK BP7ES). I also haven't vacuum synced the carbs yet. Could my poor battery be causing any of these symptoms? I'm pretty sure it is but I don't exactly know which ones, other than difficulty in starting and the lack of low-end power during my test ride.

Am I on the right track?

 

Re: lean mixture, jetting carbs

You really need to vac sync the carbs before colortuning. I think that alone may fix your issues, or at least improve them. Color tuning only affects the individual cylinder, you need to sync them to get the best power out of the engine, then colortune the cylinders to get the right gas mixture per cylinder, then vac sync again, then colortune again.

 

Re: lean mixture, jetting carbs

Today I did a vacuum sync with my homemade manometer (two bottles w/fluid) and homemade YICS block off tool, and I finished colortuning each of the cylinders (I adjusted each screw until I saw a mixture of blue and yellow flashes, leaning toward blue).

I just finished taking it for a test ride and it ran much better than last time. No more low-end hesitation, it idles nicely at ~1100rpm without any choke, and (so far) no hanging idle issues.

However, shortly into my test ride the exhaust started popping quite a bit when I got up to speed (~4000rpm). From what I've read here, this indicates a lean condition which I'm afraid puts me back where I started.

One thing I can think of is the caps on top of the stems of the carb-to-engine boots. I replaced the old ones with newer caps, but they don't fully cover the stem, and aren't as tight as the old ones. Perhaps I need better fitting ones?

Other than that, I can't think of anything else, unless I did a one of the cleaning/tuning steps wrong or I need even larger jets.

 

Re: lean mixture, jetting carbs

Success! It was the caps on the stems of the carb-to-engine boots that was leaking air and causing the backfiring. I replaced them with longer and tighter caps and fully secured them with tie-wraps (I couldn't find small enough clamps). I took it for a spin around the neighborhood and it didn't pop/backfire anymore!

I just bought some new spark plugs, so I'll be doing a plug chop soon. Should I ride around with the new plugs for a little while to "wear them in" per se, or should I be able to see any color on them within a few miles?

 

Re: lean mixture, jetting carbs

I did a plug chop today after putting in some new plugs. I just got back from doing the chop and all my plugs are black now!

I guess this means I've gone a little too far with my "enrichment" efforts, but as far as fuel mixtures go, this means the bike is "safe" to ride now, right?

One strange thing, however, is that my inner two plugs had large white areas and large black areas on the plug. While colortuning earlier I noticed that the inner two plugs were not firing all the time. Could this be the cause of the mix of colors? Plugs 2 & 3 are controlled by the right coil, so perhaps it's time to check that out?

Anyway, I guess I should try to lean it out a bit? There are a couple of washers under each needle, so maybe I'll remove one from each. I also still have the old fuel jets so maybe I can go back to those if needed.

Thanks for everyone's help with all this!

 

Re: lean mixture, jetting carbs

make sure the enrichment plungers don't even touch the lifting forks and the plungers are seating good.
what kind of muffler on the 4/1? did you change the pilot to 41?
and the mains are 124's ?
take the washers out

 

Re: lean mixture, jetting carbs

I've got a stock intake, 4-1 exhaust with supertrapp muffler, #41 pilot jets, #122 main jets, and I removed one washer from each carb today, leaving just one washer lifting each needle.

I checked my enrichment plungers and they are all seating properly when the choke is off.

I haven't done another plug chop yet, but it still runs very well when up to speed. The bike has felt a bit quicker since I've done all this carb work!

However, I think I'm starting to have some trouble with the electrics. I put a voltage meter on the battery and it's reading ~12.3 volts, but when I start the bike up, the voltage doesn't really go up, even when I rev it a bit. When it sits overnight and I start it up for the first time it will start pretty much instantly. Additional starts are more difficult, though.

I'm sure it's overdue for new alternator brushes, and I bet my battery is still pretty weak since it sat for so long, but could there be anything else that needs to be checked?

 

Re: lean mixture, jetting carbs

one of the worst things for a battery is letting it set at less than full charge but too late for that now
the washer under the needle really only changes when the fuel is applied not how much, sort of the same but different.
i have the same setup and settled on 126 mains 41 pilot 5 plates in the supertrapp and no washers alt. about 1000 ft .
maybe you could get more with a little bigger main, then again maybe not

 

Re: lean mixture, jetting carbs

I decided to have my battery tested today.

I was going to ride the bike up to the parts shop but it started having some problems when I rode down my street. It struggled to accelerate when below ~3500rpm, but did fine above that. I also heard some popping/backfiring, some of them were kind of loud.

So I parked the bike and removed the battery. I drove to the parts shop and had it tested and it passed, so I'm kind of confused now. Maybe the alternator is acting up a bit? I'm probably going to order some new brushes in the meantime.

It ran great just the other day, pulling strong from low rpm and without popping, so I don't know what could have happened to it.

I fear that "the process" is beginning to happen 8O . Does anyone know what it could be this time?

 

Re: lean mixture, jetting carbs

Start with the obvious. Make sure a carb hasn't disassembled itself again.

Pull the plugs; see what they tell you. Check the plug caps for loose resistor cores. Unscrew the caps from the wires and lop off 1/4" or so to give the caps a new bite when you screw them back on.

Check for vacuum leaks. What's the condition of the petcock vacuum line?

Maybe get some new, proper vacuum port caps for the intake manifolds; they shouldn't need clamps to seal.

 

I tried to measure the resistance of the caps/wires today.

The caps are reading ~5000ohms, so they're ok, but I couldn't get any readings from the coils. I even poked the meter leads through the wires right as they come off from the coils and I still couldn't get any readings.

I also opened up my alternator today and to my surprise:



It's very dirty and torn up in a few places. I've never opened up an alternator before so I don't know exactly what needs to be replaced (part names) or how to replace it.

Where do I begin?

 

Yuck! Definitely x-rated...........

You'll want to replace at least the brushes in that alternator, and you need to check the resistance of the rotor and the stator:

CHARGING SYSTEM:

CHARGING SYSTEM OVERVIEW:

The following guide to understanding your charging system was contributed by Dwayne Verhey, extreme XJ-Wizard.

There are two main types of alternator systems commonly used on motorcycles. Both types depend on a magnetic field, created by magnets in the alternator rotor, to induce an electrical voltage and current flow in a stationary coil of wires-----the alternator stator. If you ever get confused as to which is which, just remember that the rotating component is the "rotating rotor", and the spaghetti-like bundle of wires is the fixed-in-place, "stationary stator"......


The first type is the permanent-magnet rotor system (used on Virago, V-max, and FJR models, among others). In these systems, the fixed-strength magnets in the spinning rotor generate a constant-strength magnetic field, and thus excite the stator coil constantly; thus the alternator puts out 100% current at all times and the voltage regulator merely serves to shunt any excess generated current to ground. The advantage of the permanent-magnet system is a reduced amount of system complexity, but at the cost of increased heat and power losses (since the alternator system is generating power, and thus using up engine horsepower, constantly).

The XJ-series of bikes follows the more common automotive model, which employs variable-strength electro-magnets in the rotor. In these systems, the variable-strength magnets in the spinning rotor, when energized, are used to form the magnetic field which excite the stator. The voltage regulator controls the voltage output by varying the input voltage applied to the rotor's electro-magnets, and thus varies the strength of the magnetic field. If the system voltage drops, the voltage regulator increases the voltage fed into the rotor electro-magnets, thus increasing the strength of the magnetic field that the magnets produce, and therefore increasing the excitation (output) from the stator....and thus the alternator output voltage increases.


In both systems, the stator windings are 3-phase. Each stator wiring bundle (there are 3 of them, and each bundle is called a "leg") kicks out similar voltage, but 120-degrees out of phase with the adjacent leg(s). The resulting AC currents are then rectified (changed) to DC current via a 3-phase bridge rectifier, made up of 6 diodes, such that current in any leg flowing in either direction is directed back into the system as 12-volts DC (actually, around 13.5 to 14.5 volts DC, when everything is working properly).

If you lose a leg, or even a single diode, it is possible to still achieve voltage if the load is minimal, but as current requirements increase, the alternator will not be able to meet the challenge and the battery will have to take up the slack. Of course, as the battery drains, the available voltage is reduced, so the maximum rotor field voltage is reduced, so the current output is reduced, so the battery has to take up more slack, so ....

The end result is the battery discharges and the bike won't start.


If you suspect alternator issues, first check the resistance on the wires to the rotor. Dirty rotor commutator rings, corroded connections, etc.----all of these problems will reduce the available rotor field voltage. Next, check the condition of the connectors from the alternator to the rectifier (the 3 white wires). There's usually 2 connectors -- one from the alternator, often hidden behind the battery box, and the other near the regulator. Corrosion in these spots will reduce the stator's outputted current (bad corrosion will often melt the connector, as the outputted current turns into heat rather than being delivered to the battery). Third, with the engine running, back-probe each of those 3 white wires at a connector to ensure voltage is being generated on each leg. Finally, using a multi-meter and following the directions in the manual, check the function of each of the 6 diodes in the rectifier to make sure the power is being properly rectified from AC to DC.



Alternator Stator:

gp22) Aftermarket new or re-wound Alternator STATORS perfectly replace the originals. Rewound stator coils are sold on a "core charge" basis and you must return to us a usable, same-model stator core in order to receive your core charge refund. Re-wound stators will output at least the same current as an original stator, and comes with the wiring harness lead and connector but without the rubber insulator grommet that fits into the generator cover----so save your original grommet!

Checking alternator stators: the resistance across each pair (white1 to white2, white1 to white3, and white2 to white3) of the three white wires (white1, white2, and white3) at the connector should be as follows:

0.50 ohms +/- 10% for all XJ550 models.

0.46 ohms +/- 10% for all XJ650, all XJ700, all XJ750, and XJ900RK models.

0.37 ohms +/- 10% for all XJ1100 models.


Alternator Rotor:

gp2) OEM new and aftermarket re-wound Alternator ROTORS perfectly replace the originals. Rewound rotors are sold on a "core charge" basis and you must return to us a usable, same-model rotor core in order to receive your core charge refund. Re-wound rotors will output at least the same current as an original.

Checking alternator rotors: the resistance across the two lead wires (usually brown and green) at the connector should be as follows. Note that worn or damaged alternator brushes can affect these readings, as can "dirty" copper commutator rings on the rotor face (where the brushes contact the rotor):

4.5 ohms +/- 10% for all XJ550 models.

4.0 ohms +/- 10% for all XJ650, all XJ700, all XJ750, XJ900RK, and XJ1100 models.


NOTE: for best performance, your alternator Stator and Rotor should be replaced at the same time

 

Thanks for the info, chacal. I haven't done the tests yet, but I'm probably going to have to replace some things...

I'm still not sure about my coils, though. Did I measure them wrong, or are my coils simply bad? I'm not getting any resistance when I measure through the ends of the plug wires.

 

I found out why I couldn't get a reading from my ignition coil: it's bad!

I removed the caps from the ends of the other coil's wires and got ~12k ohms, so I think I'm due for a new ignition coil for 2+3.

I only have one question about removing the old one. The 2+3 coil is the one with the extra wire for the 750's electronic tachometer. It comes off of the orange wire and it doesn't want to be disconnected. Am I going to have to cut any wires, or is there a way to disconnect it and reconnect it to the new coil? Used coils I've seen online don't seem to have any accommodations for this wire.



So how do I install a new (used) coil?

 

Someone has spliced that wire into the original harness for some reason. The original connector has the coil lead wire and the tach lead wire "siamesed" together into a common terminal that fits into the connector shell.

The 12K reading on the secondary (plug wire) side of the coil is within specs:

Secondary (output to spark plugs): 11K ohms +/- 20%
= 8,800 ohms - 13,200 ohms acceptable range

 

I've just installed a used ignition coil to replace the bad one. I made sure to purchase one with resistance readings within spec. I also finished cleaning out the alternator and I installed new brushes.

It took a little while for the bike to start, but it eventually did and I took it around the block. I'm still having the same issues as last time, poor acceleration below ~3500rpm and some popping in the exhaust.

I think I'm going to take a look at my carbs again. My plugs are still pitch-black. Is it possible that I'm running too rich? It's the only thing I can think of right now. I still have my stock fuel jets--should I consider putting those back on, even with my 4-1 exhaust?

 

i may not be much of a help..... but may come in theory..... check the 4 headers to see if any of them arent "boiling hot". i noticed that it only takes seconds for them to heat up..... i know its dangerous, but after rebuilding my carbs on my 82 650 that sat for 15 years, it ran like dog..... carefully touched each header... one was "warm" compared to hot. figured out that after throwing my carbs in, carb number 2 jet slid its way out and onto the bottom of the bowl. put it back in and she ran great. just a suggestion to start with.

 

I know how frustrating it is to get advice from a whole bunch of people telling you to try one thing or another to fine-tune that bike.

Here is some additional information I hope you will find useful.

ColorTuning is NOT Fine-tuning.
ColorTuning is a time-saving method of "FINDING" the optimal Air~Fuel Mixture for where the Pilot Mixture Screws need to be set for the Engine to Idle.

The Bunsen Burner Blue is a perfect A/F ratio that is an ideal starting point to have all four Carbs set too when the Fine Tuning process begins.
<><>

The LEAN Condition prevalent on Bikes running Pods and 4-into-1 Headers is NOT likely to be resolved by experimenting with various sizes of Pilot FUEL Jets and Main FUEL Jets until an essential modification is done.

A MODIFICATION to insure that the MAIN > AIR < JET and the Cavity
> BENEATH < the Rubber Diaphragm is NOT subjected to NEGATIVE Atmospheric Pressure.

The Hitachi CV Carburetor DEPENDS on sufficient MAIN AIR to be present surrounding the Emulsion Tube to facilitate the SIPHONING of MAIN FUEL up the Tube.

MAIN AIR is required because it also Atomizes the Fuel as it is siphoned out up through the Nozzle.
That's why the Emulsion Tube has all those tiny holes drilled in it.

 

I pulled my carbs today to check if they were still intact and they are. I also polished the slide bores a little bit more to ensure their "clunking" ability.

I did some more electrical testing also and my rotor's resistance was way out of spec. at ~11 ohms, so I guess I'll be looking for a replacement for that.

I can't seem to get an accurate reading on my stator, though. My digital meter has a resolution of only 0.1 ohms (greater than the margin of error), so I don't think it's accurate enough (it read between 0.5-0.7ohms regardless) and my analog meter has been acting funny recently, so I don't think I can trust it.

It's probably safer to replace it anyway, but these are pretty expensive parts...

I also cleaned off all the soot on my plugs and re-checked the gap on them. Since it seems to be running very rich above idle, should I consider going back to the stock jetting? I still have the original jets.

So am I on the right track? I need to replace my alt. rotor, possibly stator, and I'm thinking about going back to the stock fuel jets since I'm running very rich now.

 

It seems I've got the bike running well again.

When I had the carbs off the last time, I removed the last set of washers that were holding the needles up. When I put the carbs on I also re-checked the idle mixtures, some were a little off from where I want them.

I'm beginning to think that my problem was running *too* rich. Before my plugs were extremely black and sooty. It was running so rich it probably just fouled the plugs. I've done a little searching on this forum and I've read stories from people who've had similar problems and many were running too rich as well.

I haven't done a plug-chop yet, and I still have to replace my rotor (stator is actually good), but it seems to be doing much better now! I'll keep an eye on it as I ride it a little more.

 

I'm gonna ask my favorite question:

How many miles are on the bike and when was the last time YOU checked the valve clearances?

Because if the valves ain't in spec, you've burned about 10 months thumping your head against the wall. I looked all back through the thread and didn't see anything about it...?

 

58k miles on the bike. I didn't post about it, but I've checked the valves less than ~1000 miles ago, when I replaced my donuts and valve cover gasket using your tutorial. The valves seemed to be within spec (as far as I can tell with a non-metric feeler gauge). I'm probably going to check them again this winter, after I buy a metric feeler gauge.

 

Do it now, it could be contributing to your headaches, honest.

 

I've just finished checking my valve clearances, here they are:

intake: 0.076 0.115 0.127 0.127
exhaust: 0.166 0.178 0.166 0.178

It looks like the only shim that needs replacing is the intake on cylinder #1. I'm waiting for the tool to arrive so I can see what shim is in there.

 

Good going. Your assessment is correct, intake #1 is the only tight one.

You'll need to stay on top of them though; intake #2 will probably be ready in 5000 more miles, as may exhausts one and three.

If you'd like to save yourself a whole lot of time in the future, "read" and record all of them now. Then you'll know what you're going to need, shim wise, when it's time to attend to any of the others.

 

So I got my replacement valve shim and installed it today and everything is within spec. Except the threads in the head for one of the valve cover bolts.



The bolt that goes into that hole in the head did not want to tighten, so I pulled the bolt out and the threads came out with it.

So...another setback. What should I do to repair the hole? My dad mentioned a product called "helicoil" that can be used to re-thread/serve as a new thread for the bolt.

What would xjbikes recommend?

 

Almost had the same problem-2 valve cover bolts were partially stripped but I realized it after less than 1 turn and managed to repair it with some PB and redirecting the bolt VERY carefully and straight. Somebody had your screw off-angle before you and just cranked it hard in.

You could use Heli-coil, it claims to be designed just for your problem. There is another alternative I used on a friends aluminum V8. It's called "Time-Sert" and basically you create a bigger hole (not much at all) and insert a metal sleeve that has the exact inner threads you just pulled out. They guarantee you'll be able to attain the same torqued condition that once existed. On the bright side there's not a lot of pressure pushing that bolt outward. I think the spec is 7ft-lbs. So it should be an easy but annoying fix.

 

Heli-Coil is the way to go.

Buying what you need to do the job might run what it would cost to have a Pro with a Heli-Coil Kit do it for you.

The hole needs to be drilled.
Tapped with a Heli-Coil Tool
The Insert installed and its Installation Tab removed.
Its a toss-up.

You could try, ...
Getting a Bolt with the matching Metric Thread Pitch.
Lube the Bolt. Lightly. ( A sheen )
Teflon Tape the Lubed Bolt.
Mix-up some JB-Weld.
Cover the Teflon Tape with the JB-Weld
Thread the Bolt into the stripped hole.
Clean the repair of excess JB-Weld before it cures.
Let the repair cure.

Turn the Bolt out.
The Bolt will retract leaving the Teflon Tape.
Dress the repair.

 

The helicoil did the trick! The bolt screws in nicely and there are no oil leaks.

Anyway, now that my valve adjustment is done, I took it out for a plug chop today and my plugs are white again. There may be a small hint of brown color on them, but it's hard to tell.

I have 41 pilot fuel jets, 122 main fuel jets, and no more washers raising the needles in my carbs. I removed the washers because I thought they were making it too rich, but maybe it was all the leftover soot/carbon from when I had two washers in each carb. I then removed one washer from each carb, but I didn't think to scrub the plugs clean so maybe that is why it also wouldn't run very well with only one washer in each.

Should I consider putting one washer back in each carb? Or is there something else I can do to enrich the mixture a bit (I'm not sure if the color is close enough for colortuning to correct)?

 

Now the valves are in spec; let's review:

FLOAT levels "wet" set using fuel and clear tubing?

Bench sync'ed?

Vacuum sync'ed with YICS blocked?

Pilot screws at ?? turns out? New o-rings on the pilot screws?

Colortuning helps set the mixture at IDLE. Plug chops are giving you a higher-RPM reading, I assume.

As for telling whether a plug actually has any color or not: Keep a brand new plug handy. Compare IT to any plug you're trying to read the color of. And remember, the insulator is less important than the "flame ring" (the ring of metal just beyond the threads that the ground strap is part of.)

Good going on the helicoil. That's what happens when somebody doesn't know about the stop collars and tries to tighten up the cover bolts to stop a leak. You're lucky it was only one.

 

Float levels were set using fuel and a clear tube.

Carbs were bench sync'ed then vacuum sync'ed with YICS blocked PRIOR to adjusting the valves (I assume I'll have to adjust the sync slightly for that valve adjustment).

I don't exactly know how far out the pilot mixture screws are, but I want to say somewhere around 6 turns out, possibly a bit more, and that may not be from completely bottomed-out. For what it's worth, I'm still able to adjust the idle mixture from rich to lean, at least according to the readings from the colortune plug.

The mixture screws do have new o-rings.

Plug chops are done at 4500 rpm in 5th gear.

 

The Mixture Screw ... "Bottomed-out" ... is Closed.
As you turn the Screw OUT, ... the Shouldered-end rises to Open the AIR Passage.
At 1.5 -to- 1.75 the Air begins to move enough to Siphon Pilot Jet FUEL

At 2.0 -to- 3.25 the Volume of AIR is regulated.

At 3.5 -to- 3.75 / 4.0 - the Passage is "Wide Open"
Further adjustment OUT only places the Screw at risk of vibrating loose and being lost.

If 4 Turns Out is not providing sufficient Richness:
Verify AIR Jets are correctly placed.
Verify Pilot FUEL Jet is correct size.
Verify Pilot FUEL Jet not clogged.
FLUSH Pilot Passages.

Flushing Tool: (Ear Syringe)


Flush Passages with Carb Cleaner pushed through Pilot Passages;
AIR Jet through FUEL Jet Opening with FUEL Jet removed and Screw Closed.
Air Jet through SCREW Opening with FUEL Jet Opening covered and Pilot Screw, Spring, Flat and O-ring removed.

 

I decided to be cheap one more time in an effort to enrich the mixture. I put one washer back in each carb and did a plug chop.

Here is a picture I took of the plugs after I got back. I know they won't look the same as they did after the plug chop, but they are kind of close. Sorry for the picture quality, I'll try to take the next pic during the day when I have some ambient light to work with.



Unlike in the picture, the tips of the ground straps were pretty white. The tips of the insulators were mostly white/light gray with some patches of black, usually on one side. The flame rings looked pretty similar, however. The ones in this picture are just a little bit sootier. I really need to bring the camera with me next time I do this.

If the flame ring is a little more important than the insulator, then what's really happening here? The insulators are telling me that I'm lean, but the flame ring is black.

 

From that picture (it is hard to tell) your plugs look fine. To be more sure go buy some brand new plugs (cheap is ok) and ride till your good and warmed up then do your chop under load over 5k. If your flame ring is good, and your insulators aren't just white-then your not lean. They don't have to be all sooty, black, or covered with fuel-that would be too rich anyway.

I'm betting you have it pretty well dialed in. How is your engine
braking? Your exhaust note? Any major popping?

 

Hard to tell from that picture, but I would say a tad rich, which is good.

 

I agree 100%, look a tad rich and just fine, even with the small pic.

I'll tell you, here in the States it's getting harder to read plugs every season. We have regionally regulated "seasonal" gas; "winter" gas and "summer" gas produce different looking plugs, with no changes to the bike in between.