carb plugs anyone know much about them

[KEITH KRAUSE]

Re: carb plugs anyone know much about them

okay my question is why is there a rubber plug covering a jet and can u leave the plug out

The rubber plug over the pilot jet is just an anti-tampering plug.
Removing it won't change the jetting or the fuel flow in any way. The amount of fuel that passes to the carb throat is regulated by the size of the pilot jet hole.
So even if you remove the plug, this "second passage" can't add any fuel volume. The pilot jet will still regulate the flow. The main jet and the plugged or unplugged entrance to the pilot jet are both immersed in fuel, so the unplugged pilot jet entrance wouldn't suck air either.

[earlfor]

Re: carb plugs anyone know much about them

That makes perfect sense and I would have to say is correct from a logical point of view. However, in practice, I have noted a big difference between how my CV carb'd 750 idled with and without the plugs. Possibly, the plugs compensated for some other factor. As for the plugs being an effective anti tamper device, I suspect they would only be effective on bikers without opposed thumbs. LOL

Earl

okay my question is why is there a rubber plug covering a jet and can u leave the plug out

The rubber plug over the pilot jet is just an anti-tampering plug.
Removing it won't change the jetting or the fuel flow in any way. The amount of fuel that passes to the carb throat is regulated by the size of the pilot jet hole.
So even if you remove the plug, this "second passage" can't add any fuel volume. The pilot jet will still regulate the flow. The main jet and the plugged or unplugged entrance to the pilot jet are both immersed in fuel, so the unplugged pilot jet entrance wouldn't suck air either.

[KEITH KRAUSE]

I can't explain why your bike would idle differently. If you look at the diagram of the CV carbs, at least the '80/81 1100 models, the fuel enters the main jet, goes through a passage, then to the pilot jet. The pilot jet entrance where the plug is, is just a little higher (carbs mounted-in relation to bowl fuel level) than the main jet. Both are still submerged in fuel. So removing the plug wouldn't change fuel flow. The rubber plugs are a feeble attempt to stop tampering, as are the metal caps over external mixture/pilot/air screws.
Other CV carbs could be modified from what I'm looking at though.

[earlfor]

yep, you're exactly right on the fuel flow and pathways, beats the devil outta me. I only found the difference because the old plugs were so hardened, I couldnt get them reinstalled, so put everything back together and had the bike running while I ordered replacement plugs. When the new plugs arrived, I installed them and there was an obvious difference in the idle.
So, my inclination is yes, the plugs should be installed, but from a logical view I dont see why they make a difference.

ahhh, but then, there are quite a few things I'll probably never understand. :-)

Earl

quote="KEITH KRAUSE"]I can't explain why your bike would idle differently. If you look at the diagram of the CV carbs, at least the '80/81 1100 models, the fuel enters the main jet, goes through a passage, then to the pilot jet. The pilot jet entrance where the plug is, is just a little higher (carbs mounted) than the main jet. Both are still submerged in fuel. So removing the plug wouldn't change fuel flow. The rubber plugs are a feeble attempt to stop tampering, as are the metal caps over external mixture/pilot/air screws.
Other CV carbs could be modified from what I'm looking at though.[/quote]

[KEITH KRAUSE]

Well, at least this "problem" can be avoided by simply re-using the plugs and then there's no question.