Silver Star doesn't run well.

[DrGonzo]

I bought my MZ not running. I cleaned the carburetor, put in a new battery and it was running. It starts well, idles well and runs well from idle to about 3k rpms and from about 5k to redline but from 3k to 5k it struggles to accelerate, surges and generally runs rough. I have set the float level, tried various needle positions and the performance has not improved and the spark plug is always black and sooty indicating a rich condition. I am starting to suspect it may be some sort of ignition fault.
I have not checked timing or valve adjustment yet. The bike had been stored inside for about ten years. It has 3700 kilometers on it. The cam timing is spot on and I did replace the regulator/rectifier.
Any known problem areas I should check?

[DrGonzo]

I may have this solved, but its raining now and I can't road test the bike. I pulled the air filter and it is soaked with oil. That no doubt occurred when I initially over filled the bike with oil, being told it was drained by the previous owner.
We shall see.

[DAVID THOMPSON]

letting it fall over when running will ruin the filter

see spark plug note below
dave

viewtopic.php?f=26&t=827

[DrGonzo]

Got a short break in the weather this morning so I rode the bike w/o an air filter. I had to run with the choke on until the bike fully warmed up and even then there was a slight stumble right off idle if you didn't apply the throttle very slowly, which seems pretty normal with no air filter and the lean condition it creates. Once rolling the engine pulled strongly and smoothly through the power band, so a new air filter WITH the proper oil level should have me running great!
Now to order an air filter and make the adapter.