wierd is perhaps not quite to right term. It is simple, too simple. It does not have a true thermostat. The thing in the plastic casing looks like one but the peripheral flange has holes all around, thus giving a minimum flow even when the disc valve is closed and the minimum is too large by far. The radiator is not too large. In very hot summer periods and city traffic, the fan(s) (if they work at all!) will dependably start up.
Both the Skorpion and Yamaha SZR have the same problem cause they have the same engine with the same non-system.
The preferred method for this is to get (eBay) the thermostat from an FZR600 3HE. "Grown-up" Yamahas have a real, thermostatically controlled system.
Try to find an offer including the hoses.
You will need a straight length of hose, (garden hose is more than good enuf) and 19mm (3/4") T, either of polyamid or brass - what you are able to find. One guy soldered one up from copper fittings.
I don't have any shots showing a MZ (I sold my water-cooled Skorpions and
mine is air-cooled) so I can only show you my Yamaha but it is basically the same thing.
The hose from the back of the cylinder (the one with the phoney thermostat) is connected to one of the two inlets at the bottom of the FZR
In the Yamaha that hose comes from above the engine in the mddle, here to be seen between the fork legs.
Then you cut the hose to the water pump apart:
using the T, you connect that new length of hose (here the red garden hose) to the other inlet at the bottom of the housing,
the original hose goes to the bottom of the radiator as before. The outlet at the top of the housing goes to the top inlet of the radiator.
Don't be mislead by the Yamaha here; it has a separate filler cap because the radiator is hidden and inacessable under the faring. You do not need this at all. Your MZ is no where near so cluttered-up.
The FZR part has the fan switch as you can see and I would connect the fans to this rather than to the radiator switch. The other small one is for an electric thermometer which, unlike the MZ, most Yamahas have. You could obtain one and mount it in that useless clock hole.
That is all there is to it. You get a true, thermostatically controlled system that dependably keeps the coolant at ±80ºC and gets to temperature in short order. Cold, the thermostat remains shut, the coolant flows thru the bottom of the housing directly back to the engine, bypassing the radiator, until the temperature of the coolant is high enuf to open the disc valve and allow flow thru the radiator, Higher temperature opens that valve more, colder opens it less, just like in any more modern car.
Over here, many do this modification, particularly in the SZR camp. They seem to be more technically inclined and interested. I mean they are more interested in optimizing the basically stock bike. The technically inclined MZ riders are much more interested in tuning. I have both and prefer the MZ, tho not for this reason here.
