Tuesday, September 30, 2014

Experimenting with my water-cooled Vespa head.

So Ive been venturing into water cooling lately and it's pretty rad! I've recently been cruising my red Ciao which is pretty quick. It has a full Malossi engine with D.E.P.S. kit, a custom 47mm matches water cooled head, 19 PHBG, and 30mm Calibrata pipe, which I scored for a killer deal. The current setup is single speed and I love it but I will probably variate it eventually for shits and giggles. I really love the look of the stock forks on Ciaos but venturing over 40mph on them is pretty sketchy, so I'll probably switch them out next season. I want to have this bike as a daily drivers so I want to eventually have a fast ass bike with very low temperatures. Anyways back to the H20 crap.... My first and funniest attempt at thermosiphoning cooling can be seen in the first 2 photos. It was more or less just an experiment and the easiest way to set it up.  If you arent familiar with Thermosiphoning, it is a cooling technique that uses convection to circulate the cooling fluid without a pump. 

 So this first setup worked, just not as good as it should. With the radiator so far away from the head and the long hoses, the cooling wasnt very effective. With this setup I wasnt seeing any temps over 320 degrees but that is easily attainable with an aircooled setup.  Also forgot to mention this is the small "snake" Polini radiator.

 Yea on the ride a few nights ago my radiator fell off and I was dragging it behind me, kind of funny. 

 This is my current and second try.  BARELY got the snake radiator tucked under the tank and shortened the hoses. I still need to do some fiddling to get it mounted perfect. I was looking at a few of water cooled moped photos and it seems like the Ciao has much less room than Puchs and French bikes.  

 Went out and went WOT for a long long while and my temps didnt get over 280 degrees. Which is pretty good but I still think it can be much better.  I really feel like the snake radiator is ultimately too small for the cooling Im looking for. Maybe I can find another for cheap and run 2? haha.

 So here are a few other radiators I have gathered for experimentation.  From left to right KTM65, Derbi GPR50, and Mini Polini radiator. So I would love to use the larger ones but I think next I will install the Mini Polini radiator due to the lack of space under the tank. Its a tad larger than the snake radiator but still thin. 

To show the thickness of these guys. The KTM and Derbi are kind of out of the question right now. I really love fenders because I ride year round, maybe I will have more room with a fork swap? 

Looks like there is a decent amount of room with the EBRs so who knows.  So far its been fun to experiment with radiators and cooling. Im planning a 50cc full H20 Polini build next year which will probably have a pump, so far this is all just practice for it. If you have experience with water cooling hit me up! COOOOL.


  1. I have been running a peugeot thermosyphon setup for over 4k miles with no issues.
    Check out the Honda NS50f radiator. It's super thin

  2. Hallo, ist der Polini Mini Radiator zu verkaufen?