I can't stop fouling plugs...

you are correct.

 

I'm wondering if you're getting fuel leaking in from the enrichment circuit. Make sure you have a little slack in the rod that the choke cable hooks up to. If that checks out, you may need to remove the plungers and make sure everything down inside is in good working order.

 

Starting-up Immediately when cold without Enrichment indicates that the Mixture is too Rich.

Check to see that the Enrichment Valves are actually closing and getting seated.

Pilot Mixtures Screws "All the way in"
Not good.

You need to find-out what size Pilot Jets are installed in the Carbs.
If you (or somebody else) put New Jets in there ... they might not be the right sized Jets for that Bike and those Carbs.

You can very easily find-out how fast over 80 MPH you are going by continuing to speed.

Eventually, your exact speed will be written down for you by a State Trooper with State-of-the-Art Speed measuring devices!

 

It has #40 pilot jets on all the carbs. Tomorrow I'm going to just get new enrichment plungers and see if that helps to seat the valves.

Hmm a cop pulling over another cop? thats funny. Oh I'm a part time law enforcement officer. Was joking on the 80mph speedo though, just said that to indicate that it was running good...

My manual says it takes only 91 octane.. I'm putting 89 in her. that change anything?

 

The Gas they are serving-up in New England is a Summer Blend with a 10 to 12% Ethanol content.

If you are a "Tweaker" and set-up Lean using the Regular Gas with all that Ethanol ... you get some Knock.

I've been doing some at the pump "Blending" ... adding some Mid-Grade or splurging for the High-test on occasion.

My Engine just turned-over 20,000 Miles. It's running GREAT!
I'm not going to risk havaing detonation spoil an otherwise perfectly running Mill.

 

True. Yeah I'll start putting 91 in it instead of 89. its only a buck or two more in the end anyway. Hey my XJ is at 20,019 miles

 

Well I'm kinda at a loss here. I thought about maybe putting a leaner pilot jet in her but I guess they don't really make a leaner Hitachi pilot jet than #40 (looked up in Sudco). There is such a thing as a 35 small round main jet for the mikuni carbs and I think the thread is the same, but really I don't think 40 to a 35 is going to make all the difference on this. I was thinking, the timing can't be off on this bike because it is set at factory right?

It has the original exhaust on it, maybe its a little restrictive like something or some stuff could have gotten up in there and clogged it a little on one of the mufflers? One way to find out would be to take one of the mufflers off and see if there is a difference, thats pretty loud though and probably not worth it I bet.

Is there air jets I could change or inspect... again... that would give rich and fouling symptoms if they weren't functioning correctly? I don't think the main jet needle on the slider could be the problem but then again it might be because it will still run on all four and be rich on all four cylinders even with the pilot screws all the way screwed in. When I rebuilt the top part where you access the sliders I noticed the needles were flush with the top part of the plastic keeper, I could pull the keeper all the way down onto the needle but that would give it more fuel so I'm leaving that alone.

I'm pretty darn sure there are not vacuum leaks because that would make a cylinder lean and not rich.

A simple test I'm going to do is put BP6ES plugs in it and see what happens. I have a friend from here that has this same bike and he's running 6ES's and he says they don't foul and run fine. But I know this bike was tuned at/for sea level so at the least it should run a tad leaner at 3500' and above all run the 7ES' doing it too.

Any new Ideas guys?

 

I've got a few ideas for you to consider,
Your PO somehow ruined your carbs before you started working on them. He may have used some chemical that eroded the inside surface where the pilot needle seats. Both he and you cleaned 2 of the carbs without removing the pilot needles, which would hold the chemical, and erode the seat. For about $75, you could start over with a rack of E-Bay carbs.

It won't hurt anything to set the floats about 1/4 inch or 1/8 inch low, and see if you can get it to run lean. The pilots should be about 2 1/2 out, not all the way seated.

Ride the bike for 10 minutes without the air filter, just to see if it is too restrictive. You did say you had oil in the airbox, an oil wetted air filter doesn,t flow well, unless it's a K & N. I don't recommend running without a filter except this test.

You seem to know what you are doing, and are experienced enough to set these carbs up right. That's why I suggest that something was done to the carbs that you wouldn't easily catch. Did somebody drill out the jets? It would be nice if you could "borrow" a good rack of carbs.

 

The Aluminum Carb Bodies are hard to hurt. The Rubber parts? That's another story!

If the Problem is that you are Fouling Plugs; easiest solution would be to Set-up the Mixtures with a Colortune Plug.

If you don't have one or cannot borrow one; you're left to experiment with the Mixtures.
Since you are fouling the Plugs; we investigate sources of Fuel and reasons that the Plugs would Foul.

Too much Fuel?
Not enough AIR?

Have the Air Jets been removed and possibly switched?
The Haynes Manual has those values reversed. It's caught a bunch of us who have done complete strips.

Main Jets?
Are the Main Jets Stock or more than one bump-up Richer?

Main AIR Jet and Passage?
We addressed the possibility of the AIR Jets being Swapped.
Is the Main AIR Passage free and clear of foreign matter?
Are the Emulsion Tubes Air Metering Ports ALL cleaned and probed?
Did you hold the Tube to a light source and peer through the Meetering Ports on one side and out the other?

Diaphragm Piston Rise?
Are the Diaphragm Pistons drilled-out beyond OEM Specs as if the Carbs were altered for a Stage 1 & 3 Jet Kit?
Is there an extra hole in the bottom of the Diaphragm Piston where the Needle Valve is attached to cause the Piston to rise prematurely?
Are the Diaphragm Needles Stock?

Pilot Mixture Screws?
Originals or replacements?
Fine thread or Ultra-fine thread?
Removable or damaged?
If removed ... are you sure the parts were inserted in the correct order with the tiny O-ring at the Bottom and were the O-rings present?

Enrichment Valves?
Free movement?
Not getting stuck open?
Are the Forks that lift the Enrichment Valves allowing the Valve to close?
Look closely at the tops of the Enrichment Valves.
Are they "Square" of are the little "Top-Hats" leaning-over and bent?

 

Well it runs great and the plugs run fine and look like they should when you ride it normally like on the highway and will only foul if you let it idle for a while (about 2-5 minutes or so) then they will start to foul. So if I just ride it and treat it like a Stock GT500 mustang and don't let it idle for very long it runs like it should and pulls hard through all the RPM ranges.

The PO could have done some sort of mod or used a harsh chemical on it and killed some rubber pieces or enlarged the pilot jets from their stock levels. Otherwise everything looks and is stock on her like the pilot jets say they are 40 and the mains say 110 but who knows they could be 45-50 pilots after all these years and the main could be a little bigger. They look like they are the stock jets anyways. And taking them out was stockish too (kinda poped loose and then unscrewed) I could replace the pilots with new ones BUT I'm not interested in taking them out for the 4th time when she'll run fine when its not idleing and is cruiseing.

Chances are the air jets could be switched but I put everything back in the way they came out in the places they came out of, so if the PO put them in backwards then I probably put them back in backwards too. I'll do a bit of light reading tonight in the factory service manual and double check everything but as of right now I'm not entertaining the thought of taking them back out when I use this bike for highway use mainly and if I'm in town I'll just rev the engine a few times at stop lights to keep it clear.

By the way, Thanks a lot guys for all your help. I really appreciate it all

 

Relax.
The Air Jets must be in right.
It wouldn't run worth a damn if they weren't.

 

thats good to here. I'm thinking of getting new pilot needles for her and maybe enricher needles. I'm thinking there could be some weird chance that they aren't seating as good as they could be. They don't cost me much so I'll give them a try. Later on like on a rainy week or when it starts to get cold out I'll take the carbs off again and replace all the jets in it. They could be worn a little maybe.

All the carbs got synced correctly and perfectly and then someone suggested I make sort of an equalizer for all the carbs by T-ing them together via the sync pipes on the intake manifolds. Doing this evened out the idle slightly and raised the idle slightly. Now I've also heard that this is a bad idea but I did sync all the carbs before I did this so is there anything wrong with having them T'd? or?

 

It was my understanding that, that is basically what YICS does.

 

Did the new needles help? I'm in the same boat as where I'm fouling plugs even thought I'm fully closed on the pilot needles. I'm thinking I forgot to take the pilot screws and oring out when I carb dipped them (yeah yeah noob, I didn't know their was a teeny tiny oring down there!) but I did take/replace every other piece of rubber off and replaced it (except for the enrichment valve dust covers).

 

Check the condition of the Pilot Mix O-Rings.

Heat the tip of a Extra-Large Safety Pin
Make a tiny hook at the end while its heated
Stick-it in your Iced Tea and cool it down

Now, you have a O-Ring Tool.
Stick the Pin down the Hole and grab BOTH small Parts.
If the O-ring dissolved ... get new ones fm Chacal.