2008 Bonneville Black Carb Issues

Try a performance shop that does carburettor Jet's and such , keihin or mikuni are generic, used by many manufacturers.
You might find them cheaper and closer than you think.

 

CVK stands for Constant Velocity - Keihin.
Model is usually a number somewhere on the body.
You are probably looking at 36mm body(throat)

 

Question: Why do you want brass floats? If they are brass now, well then yeah I get it. Else... would brass act differently when closing the inlet? MAYBE because they are heavier than plastic they might not seal as tight? And... why WOULDN'T your float chambers be filled with gas - they are supposed to be, right? perhaps others have a different experience, but, unless a float gets a hole in it the 'tangs' don't bend on their own so the float level is pretty good. And only when the hammer is down might you drain the bowls if the bowls don't fill to capacity because of bad adjustment.

I have cleaned these CVK's successfully AND unsuccessfully. One thing to note: the IDLE circuit is a tiny little hole. You say it runs fine at speed but bad idle. A logical troubleshoot might start with the idea that you didn't clean as good as you thought. That is def what has happened to me before.

IF it idles good with the choke on then is seems that the choke circuit is working. If it runs good at speed then it seems reasonable to think that the mains are spurtin' reel gud.

Does it not follow that if it won't IDLE then... perhaps... it is the idle circuit? I have explored buying one of those soundwave cleaning pots, but my third attempt at cleaning solved my problems.

Anyway, good luck, let us know how it goes so that if it ever happens to us... we won't have to wonder what to do.

 

Bowl's full of fuel = punctured or porous floats, they are sinking/heavy so they aren't closing. Hence fuel continues to flow and fill bowls.
Brass ones would be impervious to glycol/alcohol fuel additives.
Cleaning in a sonic bath and pushing a soft brass/copper wire through the Jets ??

 

Are you gonna put in new needle valves in the float bowls?
Am I to understand then, that the idle problem is because the runaway fuel from the float bowls was running too rich to burn?

I t-totally agree that leaky floats (sinks - haha very funny) are troublesome and even dangerous.

We all (well at least me) have these big ideas about what fixes it. ALTHOUGH... it COULD be that leaky floats let the corn syrup-y gas into the air inlets for the idle circuits where it dried leaving gook, causing idle problem. Then, in the process of replacing the floats you cleaned the air passages in your effort to be thorough. You gave yourself a two-fer.

If you replaced the floats AND cleaned the idle circuits you may never know what for sure caused the idle problem. A man with two watches seldom knows what time it is, right?

 

Hi Orttauq and welcome to the forum hope Capt advice solves your issues, looking forward to seeing your ride

 

If you block the intake, and if it revs up - only with the choke on...
Here is a possible: Only the choke circuit is working AND you have a vacuum leak.
Result: you sprayed in cleaner and it perked up. Your 2-4k rpm would not happen under power right?

One thing you might try... since you and everyone reading this is pulling their hair out trying to help... with the air innlet blocked, spray some starter fluid around the inlet of airbox to intake on the of the carburetor. If it surges then... there is a leak on the path to the carburetor. Kind of a dangerous procedure so be careful. The idea is that the vacuum leak is where the extra air is coming in and allowing it to run.

Now others might back me up on this or say 'no' but, if you have it barely running, then, spray some starter fluid in the intake (air filter out... direct into the carb) and your motor revs way up... then... it seems like, the choke circuit works but idle jets and main jet is STILL clogged. As I recall (help?) the idle jets are drilled in the body of the carb thus not really 'servicible' except for cleaning, but the mains are replaceable. NEW jets and needles all around would be my next try.

REMEMBER... it is not magic. It is sorta complicated to design a carb, hell, I could never do it. But, it is easy enough to understand the basics. Air comes in from the air cleaner, it passes the venturi (an hourglass shape where the air has to speed up to pass thruough the narrow part where the gas is picked up from that little tube/hole in there) where gasoline IS SUPPOSED to come out and like a spray can it mixes with the air rushing through on it's way to the combustion chamber. You seem to get fuel only thru the choke circuit. You don't seem to be getting gas because it won't rev up. Think about that. IF YOU are getting air, and your ignition coils and all that work and you are getting spark, and we know it takes air/spark/fuel to make it run... AND it runs on the choke circuit which feeds it a little 'extra' fuel when used THEN it really seems like you are not getting fuel to the venturi except through the choke circuit. Ask yourself, how can that be? The answer that strikes me is... fuel circuits are blocked and it is not getting gas. Or maybe (help anyone?) A really big vacuum leak that somehow holds back the fuel from the venturi? That seems like a stretch.

The idle circuits are incredibly tiny. To me, it is crazy that they really let gas thru em. Varnish is hard, clear, and sometimes forms what you could imagine as little one-way flaps allowing fuel to flow backwards but not forward, allows fuel and cleaner to pass thru either direction... if under more pressure than gravity. That problem does not affect the MAIN jets though. Once the slide is open a bit, the mains are supposed to take over. But they don't in your case!

I am blabbing away, and spit-balling, but... how does this sound... spray the starting fluid directly in the carb. IF it revs up, then, how can it be anything BUT blocked fuel passages or jets? Think... it gets fuel then revs up, once the start fluid burns it dies.. sounds like a fuel delivery issue.

If the starting fluid thing worked, I would think to myself that I needed to have someone with one of those 'sonic' carburetor cleaning tanks do my professional carb rebuild for me.

Sadly for the budget-handicapped people like me, repairs are sometimes past my equipment and/or skill.

But, ORRTAUG, if ignition is working, and it gets plenty of air and when you tist the throttle the slide allows more air, and the thing only works on the choke circuit... AIR/FUEL/SPARK ... the carb is at fault. It has few moving parts and does not 'wear out' like a bearing or something. The carburetor depends on vacuum to pull tiny drops of thin gasoline through tiny teeny-weeny drilled passages and even smaller jets. Varnish plugs things up.

I realize this does not count loose/separated parts on the carb itself, and does not address all aspects of vacuum leaks at critical places.

Carb is plugged up. I would like to know if anyone else has more ideas, because I do not hold myself up as some guru, and I am guessing based on my experience and success at overcoming this exact problem.

 

You may need new idle mixture jets and have to push a very fine wire (copper/brass) through the idle ports , gently working it back and forth.

 

I'd get some idle jet's and put them in and see how it works !
It should solve the issues y have, even if the Jets you get aren't the correct ones , something is better than nothing.