I agree that an intermittent ignition timing problem is very likely the cause of the poor running episodes. But I'm not at all familiar with how this Ural motor gets its spark signal. Is there a camshaft or crankshaft position sensor feeding an ignition control unit? If so, it, or a connection to it, could easily be intermittent - and should be a warranty item.
Priors: '13 K1600GT, '08 R1200RT, '04 R1150RT, '05 R1200GS, '73 R75/5.
Sailorlite screwed with this post 08-12-2012 at 02:33 PM
Reason: slight elaboration