Modern Vespa

Hello everyone, I have a problem
So, when I start the BV350, it is very difficult to reach the operating temperature. Most often, I drive from home to work and back, approx. 3.5 km. During this driving time, the needle of the coolant temperature indicator rises by two bars. My wife drives a BV300 and it warms up to working temperature in less than 1km.
I installed a new thermostat and a new temperature sensor, but the situation has not changed.
DOES ANYONE HAVE A SIMILAR EXPERIENCE, PROPOSAL, SUGGESTION?

I don't see anything wrong. My BV350 doesn't rise more than that, except perhaps on hot days when I'm not moving. Don't worry about it unless the gauge goes over the high mark, or doesn't move at all.

I think that it is not good for the proper operation and wear of the engine to work at a low temperature

Find out what the actual temperature is in C/F

And don't assume that the bars on a 300 and a 350 are equivalent

During the cold days I am covering water cooler in front with straps of duct tape. When the temperature starts going up outside and also engine starts warming up sooner, I am removing straps as needed.

You can use a candy thermometer and a pot of water on the stove to test the opening temperature of the old (or, potentially, new uninstalled) thermostat. If you really want to get fancy you can add antifreeze to raise the boiling point but don't pour it down the drain afterwards. But if you're seeing the same behavior on two thermostats I would tend to think they're both functioning as designed. Are they OEM thermostats? They can be made with different activation temperatures. And are you sure they've been installed right side up? On many engines it isn't too hard to get them in backwards, and they'll let coolant leak by too soon.

There is no point to attempting to reduce the effectiveness of the radiator with duct tape. Coolant does not circulate through the radiator until the engine is approaching the thermostat's operating temperature. The thermostat takes care of that, and running the engine a little cold - if it even is - has much more to do with fuel efficiency than engine wear.

3 km is not enough running time to bring any engine up to running temperature. The gauge may show it, but it's not.
Takes a good 20 minutes for an engine to come up to complete operating temperature. The gauge may show otherwise but the engine is not completely hot in three kilometers on any vehicle.

Checking data logs:

Starting on a cool morning the coolant in my HPE temp rises from 15C to 85C in 7mins over approx 2km. Mostly 60kph zone with no traffic lights.

Didn't pull out a thermal camera to measure the rest of the engine.

...and they are not the same for 300 and 350,......with the 300 the fan start at 100C and stop at 90C, and with the 350 the fan start at 105C and stop at 100C

tnx guys