Modern Vespa

My BV250 is dripping coolant from the engine area. It's not any of the primary hose connections. It's not from the coolant/oil pump at all. The only other possibility I can think of is that it's from the tubing to and from the carb heater, that bypasses the thermostat. I want to bypass the bypass, cutting the heater out of the system, by connecting a tube from one connection to the other.

I know that the coolant returns to the system, above the thermostat, through a nipple on the thermostat housing (cover). What I don't know is where the tubing starts, before the thermostat. I've isolated two different tubes that could be it, but without taking the carb off and tracing the lines I can't be sure which it is.

The first photo is of the upper surface of the head, between the thermostat housing and the intake manifold. There's a small rubber tube that attaches to a nipple there.

The second photo is of the housing cast into the side of the head that creates a chamber for the thermostat to sit in. There's a tube that attaches there, in the photo just above the spark plug wire.

I'm surprised no one had a comment about this, but today I decided to completely strip off the plastic and see if I could trace the hoses and figure it all out. The hose coming off the lower thermostat body seemed like the most logical source for heated coolant quickly after a cold start, and the nipple on the side of the plastic thermostat housing the logical place for a spot after the thermostat where the warm coolant would return to the system, so I connected them with a hose. The other nipple on the top of the head I can't explain, but I capped it off. Filled the coolant, hooked up the battery and started it for a few seconds. Nothing bad happened, so I started it again and it ran fine and didn't do anything weird, and so far has not leaked any coolant. Maybe it's fixed?

My 2006 GT200 had a carb float bowl heater. Several years ago, not long after I bought it, I decided to remove and clean the carb. That's when I discovered it. I just got a longer piece of hose, and bypassed the carb. Here in Phoenix, AZ, you certainly don't need a heated carb. I don't remember where the ends of the hoses connected to though. It has been fine ever since I eliminated it.

So far so good here. I took it out for a 15 mile round trip that has both streets and a freeway run at 70 mph. It behaved fine, just like you said about your BV. Our weather is generally mild, not cold, not hot, so that heater isn't vital. I'm convinced Piaggio made these scooters with commuters in mind, so they included things for very cold weather, rain and traffic. I'm retired, don't ride when it's in the 30's or when it's raining.