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From: Albrecht via MotorcycleKB.com on 20 May 2007 19:25
Charlie Gary wrote:
>I've just aquired a 1978 Honda CM185T for my son to ride, and I'm not
>having much luck finding any info for the carb. Specifically, I need
>info on the slow jet

There is NO replaceable slow jet. It's a precision drilled hole in the sprue
between the main jet and the pilot screw.

The intended hole size could be as small as 0.005 inches in diameter, but who
knows? (1)

The pilot screw adjusts fuel flow, so turning it clockwise leans up the idle
mixture.

> and the brass tube above it that protrudes from the side of the carb.

I don't see any brass tube, but it might be a float bowl vent. I don't see
what it would suck *air* unless the CM185T had a vacuum petcock.

> I have found this
>
> http://www.geocities.com/klricks(a)prodigy.net/CM185T4-5.jpg>
>but all it tells me is not to remove the jet that's pressed in.

The drawing refers to an air jet. It should be in the intake of the carb.
It's not shown on the schematic because you're never supposed to replace it.
(2)

> Is this carb the correct model for the bike? It has KEIHIN JAPAN
>molded into the slide portion of the body, and just above the float
>bowl PD is molded in. below that is a flat pad with a number stamped
>into it. The number is 98A followed by what looks to be A and W
>stamped on top of each other followed by QA and ending with a Japanese
>katakana mark my wife says is pronounced tay.

http://www.bikebandit.com/partsbandit/showschematic.asp?dept_id=2330915

16: JET, MAIN (#105) is the only replaceable jet in the carb.

(1) Mikuni makes replaceable idle jets starting at #12.5 (0.125 mm, around 0.
005 inch), and the next size would be #15 (0.15 mm). Kawasaki starts with #35
replaceable idle jets and doesn't use half sizes, each step would be .02 or .
03 mm larger.

(2) I have seen air jets of around #30 (0.3 mm diameter) in the inlets of
some carbs.

--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/tech/200705/1

From: Charlie Gary on 21 May 2007 12:07
On May 20, 4:25 pm, "Albrecht via MotorcycleKB.com" <u33665(a)uwe>
wrote:
<<Snip>>
>
> There is NO replaceable slow jet. It's a precision drilled hole in the sprue
> between the main jet and the pilot screw.
>
> The intended hole size could be as small as 0.005 inches in diameter, but who
> knows? (1)
>
> The pilot screw adjusts fuel flow, so turning it clockwise leans up the idle
> mixture.
>
> > and the brass tube above it that protrudes from the side of the carb.
>
> I don't see any brass tube, but it might be a float bowl vent. I don't see
> what it would suck *air* unless the CM185T had a vacuum petcock.
>
<<Snip>>

Thanks for the info. I can count the carbs I've had to work on on one
hand and still have fingers left, so the more I can get the better.
I believe the tube in the side is a vent for the float bowl. The
pilot screw has been reefed on by somebody, so I'll be getting a new
one from somewhere in cyberspace. The slow jet is where you pointed
out (duh), complete with plier marks from some previous hack (won't
sully the word mechanic here). The pilot jet was screwed all the way
in and then ground off flush inside the carb throat, so I will
probably have to smootherize that surface inside a little bit.
Educational for my son, I hope.

Later,

Charlie


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