No gas in #3 cyl at idle

[sidecarKev]

Having probs with cylinder #3. At idle it is not getting gas. When the bike warms up with a trip down the road it seems to be fine. I can tell when it does kick in at idle because my idle shoots up to 2800. Before it kicks in I'm around 1200. I've played around with air screws with no luck. Carbs are out of bike right now. Trying to figure out what circuit I should pay special attention to during this cleaning. I've looked at diagrams but can't exactly figure it out. Anybody know what I should be doing?

[John]

Check for a sticking float. Once the fuel is drawn down to a certian level, it may be that the float is no longer suspended by the fuel and it's own wieght is allowing it to fall, therefore opening the needle and seat valve. Also check the emulsion tube that the main jet needle rides in. There are many small holes in it, and they may be plugged. You will have to remove the diaphrams, and the main jet to get the tubes out. They push upwards toward the diaphrams from the float bowl.

[sidecarKev]

Hey John,

I don't think floats are sticking. Put new floats in and set float level. I have tried tapping bowl #3 at idle and nothing happens. Checked floats recently when I had them out of bike, nothing seems to be haging up. Had the emulsion tubes out a couple time before this. Originally there was a couple clogged holes, checked them again and nothing this time.

Thanks

[John]

Kev, I guess I don't have an answer for you. I have been VERY fortunate to never have had any major carb issues in the 13 years that I've owned Twilite Special. Even after the Big Bore Project, I didn't have to tinker with the carbs. Just another 1/2 turn on the pilot screws, and she was good to go. I am using the carbs from Organ Donor, and all of the other settings/jets are original. I know there are others here with more carb knowledge than me. Somone will jump in to help. Good luck.

[TheDjost]

I had the same problem. No fuel in #3 at idle, ran better above 2500 RPM. Turns out that the vacuum line to the petcock had worked loose. Guess where it goes... I indeed had a very big vacuum leak on #3. I just put the hose back on and voila! Check for vacuum leaks on the offending cylinder. It may be so bad that it won't create enough vacuum to "suck" the fuel up from the bowl. Just spray anything flammable(WD-40, carb cleaner) on/around the boot and if the idle changes then you have a vacuum leak.

-Justin

[pgg]

Kev, while the carbs are out, remove No3 pilot, main, and emulsion tube. Smear thick oil or suchlike on the 3 pinholes above the butterfly. Block the main jet passage top and bottom hole with fingers. Blow through the pilot jet hole. Check with a mirror to see if air comes through the pinholes. Blow through the pilot-air jet too.

[skids]

Broken pilot screw tip blocking the hole?