I have a bendix carb on my 75 xlch with the stock type "C" idler tube (I think it is also called a pilot jet). I am having a hard time tuning the air/fuel mixture and idle of the bike because it is running real rich and wants to stay at a high idle. I dont know, but I was told to see if there is an idle tube jet with a smaller hole at the bottom than the type "C." Is there? How can I fix the problem?

 

I assume your carb has two adjustments on the top of the throat.
The back one (closest to the motor) is the idle mixture screw. The front one (closest to the air cleaner) is the fuel mixture screw.

On the side of the body (towards the back of the bike) is the idle stop screw. If your idle is too high turn the idle stop screw until the idle settles where you want it. If it doesn't change loosen the screw that secures the throttle wire then press on the end of the throttle shaft (on the carb) to free it from the throttle wire and lower the idle. Make you idle speed adjustment and tighten the throttle wire again.

With your idle speed set adjust the idle mixture to the point where it runs the best. Usually done by turning it in until the motor stumbles; turn it out until the motor stumbles; then set it half way between these points.

For more details read this:

http://xlforum.net/vbportal/forums/s...ht=bendix+carb

For the adjustable main carbs there is only one jet.
If you only have one screw on the top of your bike...it is only the idle adjustment screw. For adjusting the main the only way is to change the main...for which there are several jets available.
If your carb is like this, I would assume the carb has been on the bike for a while and runs the bike just fine (unless you have made changes...pipes, baffles etc). I would be looking at other possible tuning issues before getting into the carb. if everything is ok, then for a rich fuel problem I would look at the o-ring on the jet and float level before trying to swap jets.

even the adjustable main jet carbs will need to have the o-ring replaced from time to time.

 

My bendix carb has the fuel/air mixture adjustment towards the bike on top. The idle tube is in the front and i dont think it is adjustable. It looks like a screw down and that is it. I took the idle tube out, and the stock type c hole on the bottom looks pretty big. I also used a rebuild kit putting new o-rings and other stuff on it, plus had it soaked and cleaned.

 

Using this Link as our guide for clarity:

http://xlforum.net/vbportal/forums/s...7&postcount=18

In figure 17 the author is screwing in the Main Jet adjustment needle
In figure 18 he is screwing in the idle adjustment needle; you can see the main jet adjustment needle just to the left of the idle adjustment needle

Using the following link for reference:

http://www.jpcycles.com/product/401-817

using the zoom option on the photo you can see there are large holes near the bottom of the jet where the diameter gets larger. This as the adjustable jet...there is only one size available.

using the following link for reference:

http://www.jpcycles.com/product/4000290

you can see the holes are consistently small and the jet is uniform diameter. There are different jets with different sized holes for tuning. This is for the non-adjustable carbs.