Pilot jet cleaning question

This is my first carb cleaning/overhaul, so I hope you'll forgive my ignorance. I have been doing a lot of reading in my Clymer manual, on the XJ4Ever pages, and have looked at several other tutorial posts on this site. All very helpful.

I sprayed and cleaned everything like crazy and soaked the small parts in a can of carb cleaner. However, from what I've read, it seems as though, in all likelihood, I have not yet done a thorough enough job of cleaning the small passages and jets (Mikuni on '82 XJ550). I'm wondering in particular about the tiny hole on the end of the pilot jet. Is there actually a tool or piece of wire that is fine enough (and stiff enough) to clear that opening? Same question regarding the hole on the end of that enrichment tube that sticks into the cylinder on the side of the bowl.

I know that Len sells some probes and drill bits of particular sizes and I may end up needing to purchase some of those. However, I do have some very fine bits and tiny tools as well as access to really small needles, so I may already have most everything I need. I might just need some information about the size of those tools. I know that enlarging these openings is a concern.

Thanks!

 

.009 guage guitar string (high E on an electric guitar). That's what I use so probe all the tiny holes and passages. Don't forget t he little holes in the emulsion tubes!

 

there are alout of passages that need to be cleaned spray carb cleaner and air the small hole in the pilot jet you can use a needle but dont force it or bugger it up its a small hole. what i bought was a set of torch tip cleaners at home depot wich is a bunch of different size wires in its own little case was 3 or 4 bucks. but you need to clean and reclean all the passages in the carb. pull the hats off slides out emulshin tubes make sure all the tiny holes in the tube are clear. if you clean a passage and your not sure if its clean clean it again make sure the jets go back in their proper places take your time and if your not sure on something just ask people are always herewilling to help you out

 

As for the Pilot Fuel Jets, ...
There's wire small enough to probe the orifice.

But, if it passes a Coffee Test; it's good!
I tale a sip of my Coffee.
Put the Jet between my lips.
And, try to blow the coffee back into the cup.

If a little stream shoots-out and arcs toward the coffee cup, ...
Swallow the rest of the coffee.
Jet Teat was GOOD.

If the Coffee don't spray over to the Cup, ... the Jet's clogged.
Work on it.

The Siphon Tube can be Probed with a Guitar String.
Put a Sleeve of Heat Shrink over the Carb Cleaning Tube and just
shrink enough of the end to hold it firmly on the Red Tube.
Then, ... Put the Heat Shrink Tube over the Siphon Tube and FLUSH it GOOD>

 

That's brilliant. I can't believe I didn't think of that. I've got a box full of Boomer .009s (extra light) that I use on my Strat. I should take it off the guitar first, though, shouldn't I? 8)

Is "emulsion tube" another term for the needle jet? It would be handy if there wasn't more than one name for everything, wouldn't it? Starter jets=Pilot jets, etc?

I was going to try it just now with beer but I figured, ...too much sugar in it. The coffee test will have to wait until morning.

You guys are all insane! You know that, right? This is awesome...

To be clear, though, are you saying to shrink the tubing to the carb cleaner dispensing tube AND to the siphon tube? Also, "siphon tube" is the same as "enrichment tube," right?

Thanks a million, guys!

 

yes, the siphon tube is the same s the enrichment tube

 

Just remember 1 thing when doing the beer or coffee trick when you swallow dont swallow the jet. nothing wore then having to wait several days to retrieve it lol

 

I have to make sure I don't take credit for that. It's what I use...but the IDEA came from someone else on this forum .

I think we are talking about the same thing wrt the "emulsion tube". I've also seen it called the "Nozzle." Physically, the "emulsion tube" is the long vertical tube, where, on one side, the "jet needle" (which is connected to the slide) meters the flow of a fuel/air mix that passes through the "emulsion tube" or "needle jet" into the "venturi." The other side is immersed in fuel in the "fuel bowl," which regulates the fuel through the "main fuel jet."

Emulsion is the mixture of two different fluids (I just looked that up 8) ). The tube is where air (a fluid)...flowing from the main air circuit -> through the emulsion tube -> and into the venturi...mixes with fuel from the fuel bowl (which travels through the main fuel jet). I think the actually "needle jet" is the hole at the top of the emulsion tube...that one brass part serves two functions and that's probably why it has different names.

 

That's strange, because air is actually a gas (mixture) not a liquid which makes that an improper use of the word "emulsion" according to the definition. (I looked it up, too.) I wonder why they use that word for it... Thanks for the explanation. That's helpful.

There are two other carb cleaning/tuning items that I've been chewing on since last night.

First, should I be disassembling the diaphragm assembly (also called throttle body, right?), or is cleaning the outside of it, the needle, and the diaphragm adequate? And before anyone asks, yes, they "clunk."

Second, would I be asking for trouble if I broke the carbs apart? I've read about this, too, but I really don't want to have to buy a special tool to align them properly when reassembling. It's hard to say whether or not I'm likely to do that very often, (or ever again).

Thanks again.

 

No.
You can separate the Bodies.
Mind the Fuel Rail Fittings
AND the Synchronizing Screw Tension Barrels.
If you pull the Carbs apart too fast, ... the Spring-loaded Lifters go flying.

When you put the Rack back together, ...
The Bodies have to be Level and True.
Set the vacant TOPS of the Carbs on the Flat Edge of a Level.

The Idea is to insure that the Fuel Barrels SEAT Properly and the Linkage don't Bind.

 

OK, that sounds very doable. Thanks.

And the diaphragm assemblies? Any reason to take them apart?

Last question, should I have disassembled and cleaned the plunger units? Somehow I don't remember reading anything about whether to do that or not.

Sorry to drag this out so long. I just really want to get this as right as I can my first time. Thanks!

 

Sorry to keep piling on the questions, but I'm having a hard time evaluating the condition of my idle mixture screw O-rings. Of the three screws I've been able to remove, only one washer presented itself and no O-rings came out. I have a small pin with a hook on the end that I'm using to try and get ahold of them, but they're either really tight, old, and hard, or they're not in there at all. Is that possible?

Part of the challenge is that I can't see what's down in that tiny hole. I am hooking something down there, but I don't know what it is and I'm not sure how hard to yank on it. Can I damage something by scratching around down there? The way the hook is shaped I'm definitely not able to penetrate the little hole at the bottom that the needle fits into.

Any input appreciated. Thanks.

 

Take-out the Diaphragm Assys.
De-oxidize the Piston Bore.
Search: Clunk Test

Even if they do Clunk, ... Do the Bores.

The Flats and O-rings can be stuck down in-there.
Put a few drops of Marvel Mystery Oil down in-there and un-stick them from the bottom.

Use a Pen Light and focus the beam on the Flat.
Make sure they didn't sneak-out on you when you weren't looking.
They're sneaky.
They can be both invisible and disappear.

 

Just to belabor the terminology (I know it doesn't make a difference when you clean your carbs - feel free to ignore :roll: ). A "fluid" flows (or as wikipedia is defining it "continually deforms under an applied shear stress"). Liquids are fluids, but so are gases. So the definition is technically correct

 

I've got to be honest and say that this is not what I expected to learn on the motorcycle forum. I did not know the correct definition of the word "fluid," but I'm glad that I do now.

Thanks.

 

Depending on where you are reading, the "emulsion tube" can also be called a "power valve" or a "needle jet" or a "main nozzle" or a "main jet".........not to be confused with the "main fuel jet", of course, which is the mushroom-headed brass jet that screws into the "main jet" (or emulsion tube, or power valve, etc.).

P.S. "idle mixture screws" are also called "pilot screws" or "pilot mixture screws" or god-knows-what-else screws, and, in reality, they don't regulate the MIXTURE, only the amount of the pilot circuit air-fuel mixture flow......

 

baytonemus,I know you want this done right so I can't
stress enough reading the various tutorials offered
on this site.
Rick's has written very good step-bysteps (I used for my first
time attempt and had no prob). and chacals description of HOW
carbs work also is very enlightening.
There are many more members (to many to name) that have
these carbs down pat, so just take the time to go through the
threads and you will learn the rights and wrongs of xj carb care.
Good luck.

 

Thanks, parts. I've already read both of the things you mentioned as well as chacal's other docs. They're all very helpful. I still needed some clarification here and there and forum members have been very generous. Thanks to everyone who has pitched in!

 

Pilot Mixture Screws are:
Pilot or Idle AIR Screws

Emulsion Tubes are:
Nozzle
Main Fuel Nozzle
Center Fuel Tube

I've always called them Nozzles.
I don't how they became "Emulsion Tubes"
If anything, ... They ought to be called:
Atomizing Tubes.