Idle Mixture Theory, Adjustment Screws, and Bypass Holes

Found this thread and thought I"d add pics of the HCS32 that is on the XJ650
Single hole for idle
2 Holes from Pilot circuit.
My go to method of cleaning them has been to spray them from the Pilot fuel jet plugging up the Pilot Air jet
I"ll do this BEFORE pulling off the old O Ring.
I'll start by keeping the butterfly closed then spray to open up the idle hole.
Then I'll close up the idle mix screw (counting its turns and recording). I"ll prop open the butter fly (jam a screw driver holding the throttle open if you have not pulled the carb apart yet)
That will force more thru the 2 holes. Make sure stuff comes out both holes.

 

Just so there is no confusion......note that ALL 3 HOLES pictured (the small ones) are actually passing thru the pilot fuel circuit (and adjusted using the pilot circuit mixture screw). The one small hole off by its lonesome is placed there so that it can provide fuel when the butterfly valve is fully closed (idle).

The huge opening off to the left is where the choke system (when enabled) empties into the carb throat.....note that it, too, is in front of the butterfly valve, so even with a fully closed butterfly valve (idle), it can provide fuel to the engine.

 

Pilot circuit is the same as the idle circuit. Different nomenclature; same thing.

Your proposed method for cleaning the pilot circuit holes creates a greater than 0 risk of damaging the butterflies.
If all three holes aren't getting an equal amount of spray through them, then it's time to do a full teardown and soak IMO.

 

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If I close the Pilot mix screw all the way, no fuel comes out of the single hole close to the engine, but fuel comes out of the other 2 holes. I tested that the other night. I can test it again if you think the idle mix screw is supposed to affect those holes. Its a spare carb set that has yet to be rebuilt

 

I don't understand your statement that what I"m doing is a risk of anything. This cleaning is a pre full breakdown procedure I did on the last 2 carb rebuilds. I like to do as much as I can to clear things out before breaking them down and then doing the ultrasonic bath, I"ll then check them afterwards as well. I like to look at the carbs at the start so I can learn what is clogged and what is not. For example. of the 3 carb sets I've done so far only one enrichement path in the bowls were clear w/o cleaning them. I think 4 of the carbs had one of the 3 pilot holes from my pics not flowing well. Carb set I"m working on now, the PO said "I never did get that bike running well". This one had a hole clogged in the pilot circuit. I just started on it and 2 of the bowls were clogged in the enrichment holes. It "Looked clean" but he did not obviously clean out the passages.

 

I advise that you start a thread for your bike so we aren't jumping around between other people's threads when we help you.

I realize that you are not new to carbs, but I'm opposed to using a screwdriver to hold the butterflies/ throttle plates open. Steel is harder than aluminum, and the butterfly/throttle plates are not beyond being accidentally bent. It's also possible that I misread/ misunderstood where you plan to place the screwdriver.

 

I don't put a screwdriver in the butterfly valve on the inside. THAT WOULD BE BAD. I do it on the outside where the carbs connect. I"ll post a pic. Same thing I do to hold the throttle open while I put the throttle cable back on when replacing carbs.

 

Good. I tend to just use my fingers.