VF500F newb here. Never dealt with carbs before, only FI. As I explained in my intro post, I have an 84 500. It has only 3000 miles. Previous owner cleaned the carbs right before he sold it to me. I got it home and noticed that when I completely turned the choke off, that it decided it wanted to putter and die. I pulled the thing apart, air fliter is brand new, and the carbs look spotless. My guess is the idle screw is set too low, because if I roll away with the choke half on, and shut it off right as I roll on the throttle, it runs fine. Now here is the hard part. Is the idle screw on the under side of the carb??? Can you reach it easily with the carbs on the bike? The screw that I think it is is really hard to reach with the carb on the bike. I stole this picture off of google. There is a screw that I think is the idle screw. It looks like the one up top. (Disregard the pink circle)
no that screw is for syncing the carbs the idle screw is a small knob thats connected to a flex shaft and sets to one side or the other of the bike on my vf1000r its on the left just below the carbs on my vf500 its the idle adjuster is a thumb screw in the center of the carbs, underneath them, that faces the front cylinder it usually has a lil black knob on it kinda looks like the lil black knob above the red arrow in that picture...
Looking at the picture you posted...your idea of spotless carbs and mine differ quite a little. Those carbs look pretty varnished to me. I'd be willing to bet you still got cloggage goin' on.
Oh...based on the symptom he is describing, If the idle speed adjustment doesn't help I'd presume the slow jets are still clogged, or partially clogged. If the carbs are still off, I'd have a closer look with a magnifying glass before installing them.
As everyone here has pointed out, the black knob is the single point adjustment that will increase the throttle opening on all four carbs simultaneously. The other silver screws are for performing a carb sync. I just wanted to add another thought while you are testing the idle speed theory out. If you do have some crap in the pilot jets you may be able to overcome this with an idle speed increase but only if the issue is very minor and even if you succeed, the engine will not run properly. I really doubt it will work because you have proved that by using the choke (more fuel) the engine will run, but when you increase the idle speed it opens the throttle plates and the jets allow the proportionate amount of fuel to flow. The jets are still limiting fuel if they are still plugged up so even with the throttle plates opened up, the mixture will be lean. All this to say that I think the pilots are still gummed up. Just a gut feeling. Then again I could be wrong and someone adjusted the idle speed when they were cleaning the carbs and screwed everything up, but why didn't they catch this when they tested it after the maintenance was performed? Please let us know what happens when you turn up the idle so we can follow along and learn!
You're right. If a slow or two is partially clogged you will have to turn the idle speed knob too far in to achieve idle speed relying on the two or three cylinders being fed by an open slow. The result will be RPM's won't want to drop off properly when revved at idle. Kind of a hang around 2-3K RPM. Usually if the enrichener helps at idle...the bike is lean.
