funny idle/stalling on my '85 VF700F

My project bike finally started up after months of work! The bad part is the bike doesn't seem to want to hold a steady idle, not to mention there is smoke coming out of the exhaust. I found I had to open the throttle very gently and gradually to increase the RPMs (if I throttled to quick it would stall), but then the idle would seem to go down on its own and then flutter between 2000 and 3000 RPMs, finally backing down to just under 1000 RPMs, before stalling. This is all w/ choke fully open. I tried adjusting the idle screw to no avail, but maybe I just wasn't adjusting enough? My other thought is the carbs are out of sink. What about the smoke? It also seemed to be coming from the motor itself. I wasn't sure if I should be concerned about it at first since I do not know when the last time it started. Any thoughts? Thanks!

 

First check that all 4 cylinders are firing by lightly touching each exhaust header pipe and finding which are hot or cold. Inspect the plugs for proper color.

Bike will never idle right if one cylinder isn't working.

Black smoke from exhaust could indicate that one or more cylinders are flooding with excess fuel, and greyish mist might be unburned fuel caused by bad sparkplug.

 

you will probably need a carb sync but how clean are they? you may have clogged jets and the idle circut may be plugged up as well.... do you have new insulators to put on it when you pull the carbs?

 

Carbs should be very clean. Removed the bank, all float bowl covers, diaphragm covers and all respective parts and did the pine-sol soak and left it for about a week. Came out looking new. I did a bench sync but maybe not well enough...

 

I would clean he carbs, a simple cleaning of jets and related should do the trick. Replace the boots to be sure and try that for starters. No need to make a mountain oot of a mole hill just yet. Does the trick in most cases.

 

Front right exhaust pipe is cold at idle. Plugs are brand new.

 

That's a dirty idle circuit in that carb. You cleaned all the pieces parts but missed the carb body circuits. Guess what needs to be done now? That's assuming the pilot/idle screw is set properly. About 2 turns out. And your getting spark. If you rev it up does the pipe get warm/hot?

 

Do I need to remove the carbs to clean the carb body circuits? After cleaning the carbs I turned the pilot screws 2.5 turns out if memory recalls. I will double check tomorrow. IF I can get it to idle for more than 10 seconds, all pipes are hot EXCEPT front right.

 

Check for a spark on that cylinder just before getting into carbs, but it does seem like yet another deal where someone clams they cleaned the carbs, but don't actually know how to do it methodically and properly.