KZ200, pops, misses, all RPMs

I recently bought a 78 KZ200, and it had been sitting for many years, has only four thousand on the clock, one thousand are mine. It popped and hesitated for awhile, but settled down after sea foam and marvel mystery oil. The air filter has been discontinued so i put on a cone filter from k&n. It sounded like a moped, so I bobbed the pipe just aft of the rear footpeg. It seemed to be more powerful after that, but 150 miles into it, now it is popping and missing again at all rpm's. I am thinking it has something to do with carb tunning on account of the airflow changes, but I can't rule out spark, or fuel delivery on account of I haven't checked them well yet. Or valve adjustment, for that matter..

I what order would y'all suggest the troubleshooting be done in? Anything I might be missing?

It is a manual petcock, and it is hard to really hard to turn, but sometimes it turns easy... Weird. I did adjust the idle and air screws, to no avail. Also, the rubber manifold has seen better days...

Welcome, Senor Black Hat,

If the intake manifold is cracked and leaking, replace it with a new one.

Check valve clearances. Adjust as needed to factory shop manual specs.

Inspect ignition parts. If the points are badly pitted, replace them. If they look ok, file and adjust to factory shop manual specs. If the park plug wire and boot looks cracked or feels very stiff, replace it. If the spark plug electrode looks worn or fouled, replace it. If the spark plug look sok, adjust the gap per factory shop manual.

Remove, clean and inspect the petcock, it should turn easily all the time. Be very careful cleaning its filter screen, it is delicate. Carefully flush the tank and inspect for rust. If it looks ok, reinstall these parts with a brand new inline fuel filter.

If you intend to keep the low restriction air filter and straight pipe exhaust, some re-jetting will be in order AFTER the carb is carefully cleaned inside and out. If you don't want to mess with this, put the factory pieces back on and proceed to adjust the carb per the factory shop manual procedures after a careful and complete cleaning.

I'm sure that whatever I have forgotten to include will be popping up shortly from somebody with a better memory than I.

Do you have a pic of the bike to post? We are pic addicts around here. :laugh:

Any idea where to find gasket sets and jets for the carb? Also, when going to open pipes, does the motor generally need to be leaned, or enriched?

Hope the pics pops up..

When you increase airflow you need to increase fuel flow, In other words go richer. as long as you have it apart to change jets you might as well give it a thorough cleaning. I would check the valve clearance, points adj, and other easy maintenance items too. But since all youve done betweem it running good and not running good I'd have to blame the jetting.

trying to get the pic up again..

Nice bike, looks to be in good shape.

Thanks, it is in Very good shape, and I am really enjoying this little bike. It could use more power, but it does 60mph with no problems (until it started the popping and missing, at least) and is my daily to work. You might notice I moved the rear turn signals to clear the bags, but I think they look nice in their new home. I had forgot to mention I also swapped the 40t rear for a 37t from a kz250, not a huge difference, but worth it.

so i spent all day last monday goofing around with this thing, did the points and condenser, plug, tested the coil, gapped the rocker arms, cleaned out the gas tank, cleaned out the petcock, cleaned out the fuel bowl, replaced the fuel hose and added a clear inline filter. still ran goofy. cranked every time, no problem, just still missed, so i borrowed a timing light and checked that too. turns out it was a loose cam chain all along. it was loose enough to retarded the timing just enough to loose power and miss. it is a manualy adjusted model. i should has guessed it was something like that, my chevy truck did that to me a couple years back..... anyhow, runs like a top now!

Get yourself the origional FSM kawasaki Service Manual for your bike, and you will never regret it.

Aside from having every possible spec you could ever ask, it has many shortcut and procedures lists for maintenence and repair operations.

and it will save you a bundle of $$$

GL.