I have the latest version of the ZDZ80 single - -having run many singles -of different brands - I believe this particular single to be as smooth or smoother than many twins -
This not meant as an advertisment - simply something I observed
It appears ZDZ changed the crank counterbalance -and even tho I have run a number of these 80 singles - this one IS different -
I had other flyers familiar with the 80 singles also check it out - all agreed it is smoother and very noticably so -
Maybe it is a lucky " happening - Frankly I am not certain. One monkey don't make no show -
My other singles all have a certain out of balance phase which tho slight - is detectable.
I just tried running in a particular glo single - a .46 non bearing /non ringed -so called ABC type that is the roughest SOB I ever saw - simply very poorly fit and will take some time to fit in to make it even tolerable .
It is going bye bye
Twins do have a built in design edge (boxer twins.)
However -there are some older gas twins I have run that are frankly rough as a cob---
Some guys can screw up anything --