Seemingly, I am not the only Tomos owner to have a serious weak/intermittent spark problem...and I've been lookin into why the hell that is, lately.
It seems that many early model Tomos mopeds were equipped with a CDI unit made by a company called IDM.
Now, further research indicates that IDM ignitions are crap, and rumor has it their use in the automotive industry has led to a couple recalls, not much info on that is available, that or I am lookin for it in the wrong places.
Anyhow, substantial evidence exists that the IDM Brand CDI Units are total, unreliable crap.
According to more than one source, and MopedJunkyard as well, one of the big issues with the IDM units is that they are totally incompatible with Bosch or Iskra replacement parts, and thefore the entire CDI system must be replaced.
Best price I've found so far is MopedJunkyard, for this...runs about $200, which is a bit of a hit, but Fred suggests that replacing them with the old points-style ignition is both possible and probably a lot cheaper.
So, if you have a 90-95 Tomos (other models may be affected, but these I am sure of) with a weak/intermittent spark, this may be your problem.
True...CDI Units almost never go bad, that is, unless made by IDM.
Also, don't take that as given, cause while there is sufficient evidence to note this as a factor, there's not really any 100% solid proof one way or the other - but keep it in mind.
-R