Carb Terminology

[Guest]

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?

[Hoomgar]

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?

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

[UncleMike]

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...mp%20screw.jpg

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

http://www.thegsresources.com/images...le%20valve.jpg

If so, where are the notches?

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

[UncleMike]

And now that I can access that link, are these terms just totally inapplicable to my carbs?

[jaek]

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.

[UncleMike]

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%20main%20jet.jpg

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

http://www.thegsresources.com/images/carbs/056_Removing%20main%20jet%20washer.jpg

...and screws into the needle jet.

[Hoomgar]

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...main%20jet.jpg

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

http://www.thegsresources.com/images...t%20washer.jpg

...and screws into the needle jet.

That is because you have CV carbs not VMs like I was showing you. I know nothing about CV carbs.

[UncleMike]

That is because you have CV carbs not VMs like I was showing you. I know nothing about CV carbs.

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

Thanks, though. You're great as always.

[jaek]

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%20main%20jet.jpg

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

http://www.thegsresources.com/images/carbs/056_Removing%20main%20jet%20washer.jpg

...and screws into the needle jet.

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%20slide%20out%20top%20of%20carb.jpg

http://thegsresources.com/images/carbs/097_Index%20tab%20on%20CV%20boot.jpg

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

-jake

[UncleMike]

So where is this c-clip for the jet needle located? I can't find her,...

[Hoomgar]

So where is this c-clip for the jet needle located? I can't find her,...

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]

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

[Hoomgar]

Same part number for your carbs too Mike. #6 for your carbs...

http://www.bikebandit.com/partsbandit/showschematic~dept_id~706980.asp

[UncleMike]

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

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.

[chef1366]

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.