Carb noise @ idle

I am adjusting my idle mixtue screw because I had a very lean midrange.... So I'm down on a knee listening to the engine turning the #1 carb screw out nice and slow and I notice a slurping noise that sounds irregular.... The noise is coming out of the pOd filter. I check the other side, and no such noise. I continue turning the screw and receive no noticeable difference in the idle at about 750 rpm. After finishing the other carbs I go for a test ride and it's now running it's best ever. I get back to the shop and yank the plugs. All plugs except #1 are uniform. One is quite rich in comparison.

Carbs syncd
Timing perfect
Valve shims dialed

Why does my bike sound like a 5 yr old quietly sipping a milk shake?

Check your float height and float seat condition

KZ_Rage wrote: Check your float height and float seat condition

I spent several hours working the levels weeks ago. I spent some time today to double check, and all seems well. I also cleaned the idle circuit.

Only other thing that comes to mind is that the choke on that carb isn't sealing off the enrich pathway when you close the choke off. You could move the float and seat out of #1 to one of the other carbs, same goes for the choke assembly to see if the problem stays on #1 or follows the parts. Don't suppose you have a spare #1 carb laying around?

Plug #1 is fluffy black or just darker?

I dont have another carb.
The plug is darker and a little moist.
Any way to check the choke assemblies function if in fact the problem does follow it.
How do these typically fail?

Would the choke still have any influence when the bike is warm and choke disengaged?

The choke doesn't really "choke" it just adds more fuel to the mixture.

What carbs do you have on the bike?

Guessing they're VM26 or 28's so bare with me but there is a little plastic spool that the choke linkage engages to pull open the choke plunger and allow more fuel to pass in to the draft of the carb, if that is broken or missing then it will not work properly, also the little arm that connects it to the choke shaft common to all of the carbs might be loose or tightened down incorrectly so as not to push the plunger down all the way, if the seat/seal is not closing off properly it will continue run rich.

You said you turned the mixture screw out, but how far? Did you properly "tune" the screws, or did you just put them at X number of turns?

Might want to actually "tune" them and then try things out.

My bike makes the slurp when its still cold/enrichener engaged some.

I was actually tuning them by starting them all the way in and listening to the engine as I backed the screw out. this was the only carb that didn't stumble when the screw was seated. I backed it out over 2 turns but never heard any difference and with the slurping noise I decided the spec'd setting would be a safe spot for a test run. The bike ran quite well after tuning but that spark plug was noticeably more rich and nearly fouled while all others were ideal in color.

calvin17d wrote: I was actually tuning them by starting them all the way in and listening to the engine as I backed the screw out. this was the only carb that didn't stumble when the screw was seated. I backed it out over 2 turns but never heard any difference and with the slurping noise I decided the spec'd setting would be a safe spot for a test run. The bike ran quite well after tuning but that spark plug was noticeably more rich and nearly fouled while all others were ideal in color.

If turning the pilot air adjustment screw fails to influence rpm, it often indicates an imperfect pilot circuit for whatever reason, but oftentimes due to an obstructed air passage and/or an obstructed fuel passage and/or an obstructed air/fuel mixture passage, or perhaps due to a damaged pilot screw (perhaps the pointed tip is damaged or its seat - orifice - is damaged).

Where carbs are in fact clean and in otherwise perfect condition, an excessively rich pilot circuit may result from obstruction or partial obstruction of the port where air first enters the pilot circuit, this being a smaller hole located alongside the main carb bore.

Reportedly, some pods may block or partially block the pilot air entrance port, which might be a possibility with the bike at hand. Could test run without the pod on the carb to the affected cylinder to see whether it makes any difference.

Good Fortune!

Patton wrote: If turning the pilot air adjustment screw fails to influence rpm, it often indicates an imperfect pilot circuit for whatever reason, but oftentimes due to an obstructed air passage and/or an obstructed fuel passage and/or an obstructed air/fuel mixture passage, or perhaps due to a damaged pilot screw (perhaps the pointed tip is damaged or its seat - orifice - is damaged).
The tip seemed in okay condition. I plugged a small hose into the pilot intake and with the screw seated i could not blow air passed.

Where carbs are in fact clean and in otherwise perfect condition, an excessively rich pilot circuit may result from obstruction or partial obstruction of the port where air first enters the pilot circuit, this being a smaller hole located alongside the main carb bore.

This may have been plugged, I ran some air and cleaner through the circuit which is now passing air quite freely.

Reportedly, some pods may block or partially block the pilot air entrance port, which might be a possibility with the bike at hand. Could test run without the pod on the carb to the affected cylinder to see whether it makes any difference.

This may be something to explore. I am running K&N Pods.
Good Fortune!

Swapped valves and floats with another bowl. I also swapped the starter Plungers and still it is rich. The circuit and jets are clean.

All I can think is to swap needle jets. Do these really wear out? how do I check.

If needed ---



Good Fortune!