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Carb Terminology

  • Thread starter Thread starter UncleMike
  • Start date Start date
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UncleMike

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I guess I'm just not familiar enough with this stuff yet, but I'm trying. I'm reading a lot of threads and I'm confused as all hell.

What's a c-clip?

What's meant by shimming the needle? Or raising the needle one notch?
 
UncleMike said:
I guess I'm just not familiar enough with this stuff yet, but I'm trying. I'm reading a lot of threads and I'm confused as all hell.

What's a c-clip?

What's meant by shimming the needle? Or raising the needle one notch?
Click to expand...
A c-clip is just that. Those little clips that are shaped like a letter C. They usually snap into a grove on whatever they go onto.

Shimming the needle is done when you need to raise or lower the needle half of a space. You shim it with a washer half the thickness of one notch.

The notches are the groves in the needle used to move it up or down with the c-clip.

See part numbers 22 through 26 in this drawing.

http://www.bikebandit.com/partsbandit/showschematic~dept_id~993846.asp
 
Last edited:
Thanks, Mark. Although it's a dead link. (Edit - now it works.)

So the c-clip is what they're calling the "fuel inlet needle valve seat clamp" in this pic?:

http://www.thegsresources.com/images/carbs/050_Removing%20needle%20valve%20seat%20clamp%20screw.jpg

And is this the needle we're talking about?:

http://www.thegsresources.com/images/carbs/049_Remove%20needle%20valve.jpg

If so, where are the notches?

Hoomgar said:
A c-clip is just that. Those little clips that are shaped like a letter C. They usually snap into a grove on whatever they go onto.

Shimming the needle is done when you need to raise or lower the needle half of a space. You shim it with a washer half the thickness of one notch.

The notches are the groves in the needle used to move it up or down with the c-clip.

See part numbers 22 through 26 in this drawing.

http://www.bikebandit.com/partsbandit/showschematic~dept_id~993846.asp
Click to expand...
 
And now that I can access that link, are these terms just totally inapplicable to my carbs?
 
The pics you linked to are the other needle. The "needle valve" gets closed by the float when the float bowl is full and stops more fuel from entering the bottom of the carb.

The "jet needle" sticks out of the bottom of the slide. If you stick your finger into the front of the carb (in terms of airflow) and lift up the slide, you should see a needle coming down and going through a hole in the bottom of the carb opening.

That hole is called the "needle jet". The needle blocks part of the needle jet, and thereby regulates the amount of fuel that gets sucked up and into the engine. The needle is precisely tapered along its length, so the further up the slide pulls it, the narrower the part going through the needle jet is, and the more gas can flow.

The C-clip holds the needle in place relative to the slide, by fitting into a notch on the needle. You can move the c-clip down one notch to lift the needle, or if you want to lift it half a notch, you can put a washer underneath the C-clip.

Look in the top of your carb, not the bottom.

(ps - this is why fuel injection is so wonderful. the computer figures out how fast the engine is going, where the throttle is, and tells the injector how much fuel to squirt and when to do so.
 
Hoomgar said:
That is because you have CV carbs not VMs like I was showing you. I know nothing about CV carbs.
Click to expand...

Yeah, that's why I'm wondering if it's just not applicable to mine.

Thanks, though. You're great as always.
 
UncleMike said:
I'm with ya,...

...but my carbs don't have a c-clip for the needle jet, as far as I can see.

The main jet:

http://www.thegsresources.com/images/carbs/055_Removing main jet.jpg

...sits on the main jet washer,...

http://www.thegsresources.com/images/carbs/056_Removing main jet washer.jpg

...and screws into the needle jet.
Click to expand...

The c-clip is for the jet needle, not the needle jet. I know, I know... I didn't invent these terms.

http://thegsresources.com/images/carbs/023_Removing slide out top of carb.jpg

http://thegsresources.com/images/carbs/097_Index tab on CV boot.jpg

Look down the inside of the slide (the boot attaches to the top), and you'll see it.

-jake
 
So where is this c-clip for the jet needle located? I can't find her,...
 
UncleMike said:
So where is this c-clip for the jet needle located? I can't find her,...
Click to expand...

Part number 23 in the diagram I showed you Mike. Not sure whats up with CV carbs? Do they even have one? I need to learn this stuff too since I know have CV carbs.
 
Hoomgar said:
OK here it is on my CV carbs Mike. Part #6 in this one buddy.

http://www.bikebandit.com/partsbandit/showschematic~dept_id~993865.asp
Click to expand...

Ah-ha! So we're talking about taking the slide apart completely! I didn't even know they came apart!

Thanks so much guys. For your time AND patience.

So here's the real question. I've cleaned the carbs and replaced the o-rings and gaskets. They're back together and I'm ready to re-mount the rack, I believe.

Is there anything I should be doing first in regard to the needles or jets before I mount? Just air screws to 1-1/4 turns, bench synch and slap 'em on?

No,...wait. I've still gotta check the float levels.
 
If everything is stock and you didn't change jet sizes in the carbs you should be good to go. Just remember you need to fill your carb bowls with gas or it won't start. If you have a stock vacuum petcock, suck on the vacuum line leading into your petcock with the petcock on prime and let the bowls fill.
 
Because this thread is about correct part terminology, the clip is actually called the "E"-clip. It even looks like a curved E.
CV equipped bikes in the US don't have adjustable jet needles and so, no e-clips. Canadian CV equipped models do have adjustable jet needles. So do European models (I think?).
 
Actually they do have E-clips on the needles. There is generally a spacer under the clip, then a washer and spring above it.
 
Billy Ricks said:
Actually they do have E-clips on the needles. There is generally a spacer under the clip, then a washer and spring above it.
Click to expand...
Right you are. I was trying to mention correct terminology and you one upped me.
I was strictly thinking of adjustable jet needles. Since his needles aren't adjustable I somehow turned that into "no E-clip". Can't explain that...some kind of tunnel vision reasoning thingy? Or "a senior moment" as you called it awhile back.:lol:
You obviously have to have an E-clip to hold the needles position, even if the needle is fixed.
 
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