HOW TO: Clean the Enrichment Circuit Well

Do you have a bike that won't start when cold no matter how much choke you give it? Does it take a bit of starting fluid to get it to spring to life? Does it then start right up after it has warmed up? It sounds to me like you've got a plugged Enrichment Circuit Well and it needs to be cleaned.

Where are we going to find the Enrichment Circuit Well? Unfortunately, it's located in the fuel bowl which means--yes, you guessed it--the carbs have to come off to clean them. So, pick a nice rainy day when you wouldn't have gone riding anyway and let's get to it. Besides, the first time you hit that starter button after the cleaning has been done and the bike starts right up, you'll be glad you did it.

You're going to need a couple of tools to complete this task. Chacal sells an extra long drill bit for reaching down and clearing out the Starter Jet at the bottom of the well. I personally used the smallest rod from a cutting torch tip cleaning set. I laid it against a grinding wheel to make a long tapered tip. (If you do this, be very careful with it. It's like a very long needle.) Aerosol carb cleaner is a must, too. Something with the little plastic nozzle on the can, too. I'd recommend filling the well with the carb cleaner and letting it sit to soak for an hour or so before you get after it.

Now to the Enrichment Circuit. After you remove the carbs and their fuel bowls, you'll notice a brass tube sticking up (down) from the bottom of the carb body. This tube extends down into a well. This is what we are after. When you apply choke, a valve up above opens and pulls fuel up from this well to enrich the fuel/air mixture entering the engine. This enriched state is what helps get the bike started when it is cold. If the passage way into the well becomes plugged, fuel won't fill the well and you won't be able to start the bike with out adding some fuel from an external source (starter fluid).

That said, here is an overhead shot of what a typical Hitachi fuel bowl looks like and where we'll be concentrating our cleaning efforts:



The upper port bisects the well at about a 45° angle. Fuel from the bowls flows into the lower portion of the well from the fuel bowl. Due to this downward angle, sediment and crud tends to collect at the bottom of this drilled boss. Here's another sectional view to help you better "see" how these two holes intersect. (Note: this picture depicts what I "imagine" they look like. I've not cut one in two to find out for sure.)



With your tool, you'll want to carefully probe and remove any obstructions in these two passages. You can use the carb spray to help flush debris out of the hole, too. The acid test to know if you've got it properly cleaned is to place the straw from the carb cleaner can up tight against the passage leading into the well and spray fluid into the hole.

[flash=425,350]http://www.youtube.com/v/9yBwrcqwArA.swf[/flash]

If you've done a good job cleaning, carb cleaner will literally spray out the well in a stream about ten feet. It has to be in a stream--like from a squirt gun--to be considered cleaned.

Oh, and remember while doing this...



Here's a picture I stole from FinnogAngela showing a properly cleaned well using a bright pen light.



But, remember, the Enrichment Circuit Well is only half the Enrichment Circuit. While you're at it, you might as well finish the job by making sure the tube that drops into the well is also clear. Once you're satisfied you've done a good job, put her back together and be amazed at how easily your bike will start.

Cheers!

(Special thanks go to Rick, Carl and Len for their input over the last few months. Without their collective insight and knowledge, this how-to wouldn't have been possible.)

 

works for me... great write-up and thanks for all the help....

 

Exceptional!

 

Thanks, Len. What's the tool number? I'll add it the text above.

 

Getting squirted by the discharge of Carb Cleaner from clearing-out the Starter Jet Well is your Baptism into the realm of Carb Cleaning.

I don't care how many times you do it ... you get a face-full of Carb Cleaner sooner or later.

Those nasty Engineers designed it that way!

 

Here are the drill bits:

z7) Aftermarket wire gauge Drill Bit for Bowl Starter Jet. As you will quickly discover if you ever try to clean or rebuild your Hitachi carbs, the tiny, non-removable starter jet that is stuck wa-a-a-y down at the bottom of a drilled passage in the carb bowl is next to impossible to clean. For one, did we mention that the jet opening is TINY? And did I also mention that it's stuck way down at the bottom of a small passageway, and basically unreachable? AND THEREFORE, NO ONE EVER REALLY EVEN ATTEMPTS TO CLEAN IT OUT? And that a clogged starter jet not only means trouble starting and idling, but that starter circuit is actually also involved in idle and off-idle performance? Well, how do you actually clean it? Even the tiniest cleaning rod in our HCP950 and HCP953 carb passage cleaning sets (above) aren't small enough to fit through this starter jet (it is THE smallest jet-passage in the entire carb)...

Well, here's how you clean it: with this tiny drill bit. Just big enough to get through the jet, but not big enough to ENLARGE the jet (that's a huge no-no), this high-speed steel bit can be gently rotated (but never "pushed", as it will break) through the toughest of crud. This is the only way to properly clean these starter jets.

NOTE: this is a TINY drill bit, and will not chuck into a standard drill chuck. You have to use a mini pin-vise attachment or do it carefully by hand...... ALSO: this drill bit is a mere 1-1/2" long, and as such, will disappear below the top "plane" of the bowl as it goes down into the jet. You will have to use a pair of very slim needle-nose pliers to grip the tip of this drill bit and rotate it!


HCP2296 Starter Jet Clean-Out Drill Bit, for Hitachi carb bowls used on all XJ650 (except Turbo) models, all XJ700 non-X models, and all XJ750 models.
$ 11.95

HCP2293 Starter Jet Clean-Out Drill Bit, for Mikuni carb bowls used on all XJ550 models, and all XJ700-X models.
$ 11.95


And here is the wire rod cleaning set:

p1) Mini-Sized Carb Passages Cleaning Tool Set: set of 13 small wire tip cleaners, sizes #6-26, in a handy aluminum flip-open case. The #6 and #7 wires are the only sizes small enough to fit into the tiny jet passages and emulsion tube holes and clean them properly (without the risk of "re-sizing" the hole by mistake).

HCP950 Mini Carb Cleaning Tool Set
$ 7.00


HOWEVER, I have found that even the smallest wire in the HCP950 set (size #6 wire rod) is NOT small enough to clean a Hitachi starter jet without getting the feeling that I am enlarging it somewhat (the wire rods in these torch cleaning sets have serrated edges, so that the wires can be used as "round files" in a sense). And the Mikuni carbs have even smaller starter jets than the Hitachi carbs, from a #35 size in the 550 and 700X models, all the way down to a #25 size in the 1100 (and that, baby, is SMALL!). I have not been able to source any wire size drill bits that small, in a long enough length, to be able to offer for starter jets smaller than a #35 size.

I assume that "slight" enlaragement of the starter jet is a no-no, although it may result in just having to use the choke "half-way" rather than full-on in cases that require such a large choking (enriching) action.

However, I am working on getting a special tool made that merely has a short (1/4" long) probe tip, attached to the end of a long shaft, that can be used for this purpose. The drill bit method, although it works, is cumbersome (at best), but it is the easiest way to do it, of all the alternatives, when the starter jets are plugged tight (like, in 95% of the bowls!).

Finally, just for curiosity sake, I notice that the 1980 XJ650 Maxim carb bowls show, in the parts diagrams, a removable starter jet. I've never had one of these bowls, so I can't say for sure, but I have no reason to suspect that the factory lied about it! For all other models, Mikuni and Hitachi, the starter jets are pressed into the bowls, non-removable, and thus cleaning them is such a chore, but is one of THE most important tasks that needs to be done to get the carbs performing correctly.

That, and replacing those darned throttle shaft seals.......

 

Yep, and it's no fun, and can easily lead to terrible, irrreprable eye problems.

When the jets are clean, and you spray carb cleaner through the little entry port in the bottom of the carb bowl, the stream that comes out of the other end of starter jet IS VERY FORCEFUL, and will spray a good 10 feet out.

If it helps, imagine spraying carb cleaner DIRECTLY INTO YOUR EYES, straight out of the can. That's what it's like.

No fun. Seriously dangerous. Be MORE than careful!

 

Just a quick note...

I knew I had this "problem" with my '81. When I bought it last year, the PO claimed to have had the carbs rebuilt by his neighbor right before he put it up for sale. I just pulled the carbs and checked them with the carb spray: three of the four bowl's Enrichment Circuit Wells were plugged. No wonder it wouldn't start without starter fluid. All four are shooting now. I've installed stainless drain screws in the bowls and am headed back out to reinstall the rack on the bike. I can't wait to see if the bike starts right up.

 

If three out of four of those starter jets were clogged ... you're going to get much better starting now that they are cleaned-out.

MUCH Better!

 

I just got back in... SUCCESS!!! Happy Dance! No more starter fluid to start her on cold mornings. It sprang to life almost immediately.

Oh, and I added a video to the above showing the carb spraying out the well.

 

Although short, and to the point, that is the most exotic, erotic, and Exciting video I have seen in a LONG time.

Let's call it "Starter Jet Porn" for XJ Bowls...........

P.S. Also, kids, note the correct and proper way to test spray into that well----with the bowl well pointed COMPLETELY away from you!

 

^^^ I don't care who you are, that's funny right there! :lol:

 

I have to agree with the "Damn you Yamaha..." I have never felt a burning quite the same...

But, just a thought--I used a really tiny hypodermic needle. I don't know how one would get legitimate access to one (my lab had a collection of them, which I had to use under the supervision of the lab manager, then give right back to him). It worked perfectly though--I actually had a piece of something that looked suspiciously like tank rust (must have been in there a while, because I have coated the inside of my tank and I have an inline filter as well) really jammed in one of the holes good. Would never have come out just using cleaner.

 

I had a clogged jet on one of my Mikuni float bowls. Two days of soak time in the carb dip, and it opened right up. Didn't someone else say they used drain cleaner?

 

Drain cleaner will dissolve about anything! But it runs the risk of staining the finish on the carb bodies and bowls and making them a really ugly, streaky grey color...........

 

Ooh hey thanks for the video. I thought I had mine cleaned pretty well, but the bike still fights to start. I was getting really frustrated again, but the video clearly shows that I didn't do a good enough job. This is a great thread and it was sorely needed. I think it was probably the fastest sticky ever.

 

Yeah, we'll all gotten the fluid shot to the eyes. I where eye protection now whenever the fluid can comes out. ALSO, be careful of the fluid blast getting in your mouth. You'd think the stuff would taste terrible. BUT it tastes very sweet.... like candy or frosting sweet...and starts to burn like crazy after a bit, too. Had that happen just last weekend. So the moral of the story is: keep your mouth shut, and don't look.

 

Another way to clean that little orifice out is to heat that side of the bowl where it is with a torch, CAREFULLY. Go slow, and your patience will be rewarded.

You will see a little wisp of smoke if the orifice was clogged with varnish, then just hit it with hi-pressure air, done!

 

Okay I know this thread is a little old but I have a question.
The little "pipe" (copper it looks like in my case) that goes down into the well. How do you clean it? I understand it sucks up from the well but where does the gas go from there? Spray carb cleaner "down" somewhere and through the "pipe" and out it comes?
I hope this post isn't as confusing as I am confused.

Thanks

 

There is a wire Cleaning Tool of the right diameter supplied with a selection of other wires fitting the Jets and Metering Ports in a Standard Welders Tip Cleaning Set.

Small aluminum case.
Available at Weld Shops and well-stocked Hardware Stores.

Set pictured here with wire extending through Emulsion Tube Port: