Idle mixture screws?

[LoHo]

I have removed my idle mixture screws and was looking over Talbot's excellent pics of "Broken tip removal" techniques. Looking them over, I began to wonder how pointy those screws are supposed to be? All of mine are of a length and appear intact, but are not sharp. Mine are about "fine tipped pen" sharp, not "needle" sharp. The ends are squared off. Is this SOP or should I look for broken tips?

[prometheus578]

Fine tipped pen is good.
And as long as carb spray can squirt through the hole in the carb throat, I'd say there's no point broken off in there.

[Ken Talbot]

The needle tips on your G, and those on H carbs are blunt. Only the E and F carbs have the very pointy tips that are so prone to breaking.

[prometheus578]

Thanks, Ken, I wasn't aware of the differences in models. Guess I can add my head to the list of things that are pointy!(Or is that dull and blunted?)

[skids]

Ken, are you sure about that? I remember getting into two sets of 78 carbs that seems to be stock, and whick had somewhat rounded tips. The 80 and 81 sets of carbs have tips that actually protruded clear through the jet hole into the carb throat when I had the pilot screws all the way in. I did get a K&N kit that had pilot screws "for the 78" model that I chose not to use because they were more pointed than stock. Maybe I am loosing my mind?!?

Originally posted by Ken Talbot
The needle tips on your G, and those on H carbs are blunt. Only the E and F carbs have the very pointy tips that are so prone to breaking.

[LoHo]

That's one of the things about our bikes...unless you've owned it since it was new, there's no telling who's done what to it. Consider how many list bikes are sold after an owner can't solve some problem... then we get a new guy talking about a PO who put Honda carbs on a 79 XS...

[LoHo]

Ken wrote:
>The needle tips on your G, and those on H carbs are blunt. Only the E and F carbs have the very pointy tips that are so prone to breaking.

Now, how would I have found this out without this list?! I love this place!

[xj11john]

ok, so does one meter air the pointy ones meter fuel??

I have an xj and I am tring to get the last plug the right nice brown color as opposed to grey, and I cant remember which way to go, Ive messed with it so much, in or out??

any help would be helpful, thanks in advance.

[John]

Pilot screw in= lean. Out = rich

[Ken Talbot]

For reference, here's a couple of shots:

Upper needle is a broken-off early style, lower is an unbroken later style. Note that the early ones were one long taper from just below the screw threads, while the later ones were a stepped profile. Reference is a Pilot brand Fineliner


Next is a shot of a broken-off tip still sticking into the throat of an older carb:


Last is a shot of the tip of a lightly-seated needle sticking into the bore of a later model carb. This needle has a noticeably flat 'point'.

[DeanR]

Hey Ken, Your great pictures always zero right in on the area of interest in great detail. How about collecting them all together into an XS atlas!

[xj11john]

Ken is the man!

I still say he could make a good living at photography.

[skids]

Thanks, Ken. I wonder if all of my early pilot screws are broken or rounded off somehow. Oh well, they seem to work OK. I have to wonder however if the partially protruding tip (if there would be at 1.5 turns) is to produce a better spray for smoother running???

[QUOTE]Originally posted by Ken Talbot
[B]For reference, here's a couple of shots:

Upper needle is a broken-off early style, lower is an unbroken later style. Note that the early ones were one long taper from just below the screw threads, while the later ones were a stepped profile. Reference is a Pilot brand Fineliner

[prometheus578]

I stand in the shadow of greatness

Ken is the man!

I was gonna write the same thing last night, John.
...the dedication!
Imagine the trouble he went through... breaking off a needle in his carb just to take a photo of it for us, as a warning.
Truly, he is the Man.

Your Humble Servant.

[Ken Talbot]

Sid - even with broken/rounded off pilot screws, things could still work okay as long as the orifices are clear. You would be able to confirm this by poking a fine piece of wire in there. Adjusting the screw in far enough would seat it against the carb body and completely close it off, and opening it would have much the same effect as intended. However, this would amount to an almost all-or-nothing effect compared to the gradual progression you would get with an unbroken tip still working in the tapered orifice. Because all of this really only applies to low engine speed operation, it is probably not something you would notice for long. IIRC, I didn't spend much time idling along at low engine speed any time I've ridden behind you...