In theory, it works. Treating the symptom doesn't fix the problem. The root cause of the problem is poor, corroded connections. If this was a real problem, it should have manifested itself when the machine was new. These machines don't ride in the best of conditions - deep water and mud followed by dusty trails, etc. They take more maintenance that the family car. It doesn't take much resistance due to corrosion to lose 2-3 volts at the starter.
It is most definitely a Linhai-550 then...
I wish Massimo (and others) would stop doing that--493 cc is at best a "500", stretching it to 550 in the model designation is a bit much. Years go I has a BSA 441 Victor. guess how many cc displacement it was?