Pilot Plug - Aluminum or Rubber or Other?

Which is your personal preference? I recently did a carb rebuilt and the aluminum/o-ring plug went in fine, I just prefer a good snug feeling which it did not give me. Which holds up to modern fuel and stays put is my overall question.

i replaced the o-ring with a slightly larger one in my kz400 carbs and it worked great.

McKinneyRacing wrote: Which is your personal preference? I recently did a carb rebuilt and the aluminum/o-ring plug went in fine, I just prefer a good snug feeling which it did not give me. Which holds up to modern fuel and stays put is my overall question.

What bike and what brand carb ? and will the same plug fit a range of carbs?
My Keihin CV 34 carbs take a plastic or is it neoprene plug with o ring over the pilot jet and if i ever drop and lose one I have a problem . I have seen metal plugs with o rings and think these were for a Mikuni BS34 . Wonder if they would fit Keihin carb? or any size CV32 CV34 or CV36.

Personally i dont care what they are made off but an availabe alternative would be nice.

I tried straight rubber plugs made for a GS or goldwing a few years back but they fell out after a week. Seems the Mikuni carbs have a bowl design to hold them in place. Something the Keihin float bowl doe not have.

I understand that some bikes for whatever reason block off the pilot circuit from factory but can anyone tell me why? And how do they get around The whole not having a pilot circuit? Shorter needle? Skinnier tapered needle?

It depends on the ones over the pilot screws or the ones over the pilots.
The screws are covered so they can't be tampered with. The ones over the pilots are so they have to get fuel through the main circuit.
The first isn't needed, the second is.
Steve

We are talking inside the bowl...

The carbs that have a plug over one of the jets, have an alternate passage for fuel to get to the covered jet. The pilot circuit is not removed, it just gets fed differently. Not sure why some need this and some don't. It seems more like a modification to an earlier version of the carb, like a change to meet some emissions mandate, etc.

Two different model carbs can sometimes look almost identical, but one will plug the pilot, or intermediate jet. The blocked jet will sometimes get fed through the main jet.

Ah, I see. I've never personally had a bike with this particular feature, seems like a cheap work around alternative to sourcing a carb that better suits the motor.

I know that. Just explaining to crusher the two types. The one connected to the main circuit is to limit how much the pilot circuit can get.
Emissions. :pinch:
Steve

Yes I'm referring to the BS34 series carbs. I've been working on several of these cop bikes, and it seems that the previous owner simply left the plugs out of the carbs or they came this way from the factory. I saw the rubber plugs for sale at Z1Ent. but wasn't sure how well they held up to modern fuel and ethanol exposure.

Looking down the pilot jet hole, they are fed via a small passage from the main jet. I know two of these bikes seem to run fine when we rode them back and they didn't have any plugs either.

If I'm not mistaken the passages are after the main jets. If that's the case, you have a wide open with no jet metering the mains.
Steve

here is the theory.
most carbs have a main jet and an idle jet which suck fuel from the float bowl. if you change the pilot, it WILL affect the main jet ever so slightly, but the difference is really insignificant.

Some carbs feed the pilot circuit from the main jet circuit. Theory here is the huge main jet flows plenty for the pilot. If you change the pilot, it won't change main jet performance, as it all still flows through the main.

So, those which feed the pilot from the main jet have the passage way mentioned. this passage way CAN be plugged.
Also, the style of pilot jet can be different depending on which way it feeds.

some guys convert some carbs. they remove the plugs, the plug the passage way between the main and the pilot. seems silly to me. seems much easier to just leave the plugs in.