It's alive..it's alive..but..I think it misfires

On my K550Z-C3 LTD project, I installed a new clutch cable, throttle cables, battery, handle bar, spark plugs, fuel/vacuum tubes, oil filter, fresh oil, front tire. I fixed the starter switch. I also opened up the carbs and found some missing choke flaps. Made some new flaps out of tin-can metal and installed them on the choke assembly. Cleaned the carbs as best as I could and installed new O-rings as need. I then put the carbs back on the bike along with a few new air ducts to the airbox. Put some fresh gas in the gas tank, activated the choke and hit the starter switch. Viola, the engine came on roaring and I was super happy.

But after setting idle, I realized that the engine was misfiring in one of the two cylinders(I think) on the left side. I put my hand over the left muffler and could feel the misfiring. I was wondering what the best way to diagnose this problem was. During my carb assembly, I did find one float valve getting a bit stuck. I had to pry it out of it's stuck position and it seemed to be ok but I was not comfortable with the way it installed. However, I don't see any evidence of gas flowing out of the carbs or any such thing. Any clues on what to start looking at is much appreciated.

If the float is stuck in the shut off position, the carb will run dry. If it's stuck in the open position, the carb will overflow. If it's stuck barely open, it may run low but enough to give you some misfires.

If the carbs are heavily out of synch, it could also be missing on one cylinder. But it should then stop missing if you rev the engine.

Another possibility is a clogged idle jet circuit, even if you've cleaned the carbs.

A poor spark will also cause misfiring. This can be caused by several things, from a bad spark plug to a bad cap to a bad HT lead. Since only one cylinder is missing, it should not be with the coil or points/pulser/pickup/whathaveyou.

Finally, it can be a lack of compression on that particular cylinder.

Personally, I would start by determining exactly which cylinder by briefly pulling off one spark plug cap at the time. Once satisfied you have the correct cylinder to work with, I would start by swapping the spark plug leads with the paired cylinder. If the miss is with cylinder #1, swap with #4. If it's with #2, swap with #3. If the same cylinder is affected, the problem is not with the ignition system. Just to make sure, also swap spark plugs - regardless with which cylinder - to eliminate also that.

If that doesn't change anything and the carb with the fuel level issue is also the cylinder giving trouble, hook up a clear plastic tube to see what the level is when running and if it remain constant.

"During my carb assembly, I did find one float valve getting a bit stuck. I had to pry it out of it's stuck position and it seemed to be ok but I was not comfortable with the way it installed."

This sounds as though you would have a problem here. The valve may very well be not functioning properly. Also Prying, may have changed the adjustment for the float height/ fuel level.
Start with the basics, as Faffi explained. Be sure of compression, check the ignition, etc. Check for vacuum leaks, dirt in your tank, etc. Do the carbs right, and it will run properly. You do have the service manual for your bike?

Thanks for the replies.

And you are right, I suspect it's the bad/stuck float valve. I was certain that the float with the problem valve was not moving as well the other were. But I did the newbie thing and assumed that it would be all OK. I'll order the float needle valve assembly from Z1enterprises and replace the valve.

Also, can someone point me to some really cheap vaccum guage/s that I may be able to buy online to help with the fine carb tuning? Also, a compression gauge would come in handy now (I think).

No eBay APP ID and/or Cert ID defined in Kunena configurationI found this here for the vacuum gauge. Will it suit my needs?

No eBay APP ID and/or Cert ID defined in Kunena configurationAnd this for the compression gauge?

Yes, the manuals from Lou's signature have helped me tremendously. I'm doing this for the very first time and I need all the help I can get.

No eBay APP ID and/or Cert ID defined in Kunena configuration

Bunty27 wrote: I found this here for the vacuum gauge. Will it suit my needs?

No. You cannot synch the carbs using a single gauge.

Maybe I don't understand the process but I was thinking of taking the reading one cylinder at a time but are you saying that it won't work?