Coughing out the tailpipe

My bike coughs a lot whether idling or at 5000rpm. I did a search on this subject and came up with this:
My plugs are gapped properly.
No air leaks detected.
My timing is on.
I have new coils with dyna ignition.
There is a spark at all of the plugs and all four pipes get hot.
The bike idles best with the idle screws out 3/4 of a turn even though the manual says 1 1/4.

I just cleaned my carbs and put them in. I bench sync'd them and all four carbs look even. Would this problem go away if I sync'ed them with an actual tool?

Post edited by: Ray J, at: 2007/06/04 19:54

on the stand or on the road?

And does it run fine other than the noise?

The problem might go away if you actually sync'd the carbs with a proper manometer. You might also read the COIL REPOWERING tip on our website under wg's Tech Stuff Index.

I have not had the bike on the road yet, Oh captain my captain. It just farts too much sitting there in the garage and I don't want to embarass myself.
WG, I installed your relay a year ago and it did wonders. The plugs are still black, though, so I will check the voltages, etc and see if I can get them sync'ed. I am heading out of town for a few days, so I'll get back to you when I get back to it. Thanks.

Ray, Have you check valve clearances? If the plugs are sooty, that is a likely culprit. Also, what type airbox/filter are you using? A dirty air filter will soot up plugs in a jiffy. Do you know how the carbs are jetted? The stock jetting works OK with pods on a 76 with just a bump in main jet... perhaps to #120 mains; in other words if you have pods, leave the jet needles on 3rd clip slot and #17.5 pilots alone. There is also a possibility that the internals are just dirty and air isnt' getting through as it should from the air jets but this would typically produce varied plug readings rather than consistantly sooty across the board. Last is spark plug heat range. You are using NGK B8ES I hope?

Change the oil and replace the plugs, they are now junk.

I finally got back to the bike. I made a homemade carb balancer and balanced the carbs with that. The homemade model is like shooting in the dark, you really don't know what you are measuring. It would be nice to know the actual pressure. The bike still coughs a little and surges a little. It is driveable, but it is not close to perfect.
WG, I have the original airbox. No pods. New square filter. Plugs are black. All of them. They are the NGK's. I took out all of the jets and could see through every little tiny hole. The original jet needles are in, center notch. Do the jets matter if the bike is rough at idle? I thought the jets were not drawing any gas/air at idle.
I have never monkeyed with the valve clearances. I have to change the valve cover gasket, so I might as well dive into it. But the 'special tool' is $60 at z1enterprises. When they say 'special', are they talking about the price? Do I need this tool, or is there a way around it.
CQ, why should I change the oil? Do you think something got in it? I was thinking of changing the plugs, but I want to wait until I know they will not get sooty again, so I might just clean them for now.

Post edited by: Ray J, at: 2007/06/09 12:15