Modern Vespa

I purchased a 2006 Yamaha Vino 50 which is now running great but the red temperature warning light continues to light up after about 7 miles.
Yamaha changed the cooling system on their Vino's in 2006 from a 2 stroke air cooled to a 4 stroke water cooling system.
The first ride the warning light lit up quickly. Checking the fluids I was surprised to find a radiator and water resevoir which were both bone dry. Since then I have cleaned the thermostat, all hoses checked, and am now on my final flush of the system. I've also changed the oil and air filter. So now I can get 7 miles before the warning light activates. So if I would take it to a Yamaha repair shop, how would they diagnose and fix the problem? What am I missing?
Also the engine oil shows no sign of water.
Also I'm surprised how little water/flush the engine holds when re-filling?
Thank you,
Joe in Carefree, AZ.

It sounds like the thermostat may be stuck shut. You could test it by plunging it in a pan of hot water. Or simply buy a new one.

My '06 Vino 125 was air cooled.

Yeah, back to the thermostat, I've seen the video where it shows how to test it.
Thanks.

It's probably your temperature sensor. This goes bad and gives you a false trouble light. 5JJ-83591-00-00 is the Yamaha part #. I can find $13 replacements for the fuel injected 4 strokes, but not as many options for yours.

Thank you Abner. I noticed the temp sensor and it appears easy to get to. I'll replace it when I pull out the thermostat.
Can I run the bike without the thermostat? Would that help to determine the problem?

You should be able to remove the t-stat (#1) and put the housing back in place to run w/out. I'd cut a gasket out of a cereal box or something. I've worked on a lot of these little liquid cooled Yamahas (Vino, Zuma & C3) over the last 12 years. I have yet to see a thermostat fail. I might try that first though if you can get to it easy enough before I spent asking price on the sensor. You're perfectly safe to run the scooter without it in place. Put it all back together w/ distilled water in the system. Fire it up, ride it around. If the light comes back, you know it's not because the thermostat won't open.

Is it just the temperature gauge, or does it actually seem to be getting hot? I see you live not too far from me. Whatever you do, DON'T put water out of the faucet in it. Faucet water in the Phoenix area is about 5% calcium chloride. It will completely destroy a cooling system due to corrosion, especially on an aluminum engine. Always use distilled water for testing. I use Maxima motorcycle coolant in my liquid cooled bikes. I wonder if the temp sensor could have been damage from running it with nothing in the cooling system?

Chandler Guy, the scooter does not seem to be running hot. Thanks for the advice of not using tap water ever. I'm getting better at dis-assembling all the plastic to reach the motor so I'm going to remove the thermostat and recheck all the hoses to see what happens. The small amount of flush/anti freeze that I load into thr radiator bothers me. The volume is low, seems like only enough needed to fill the radiator. I would think more volume needed to fill the hoses/system?

Is there any place to fill it besides the radiator? Remove the radiator cap, start the engine and let it run. when it warms up and the thermostat opens (assuming it is working properly) the water will start circulating, and that will bleed the air out of the system. The water level in the radiator may drop. There may have been an air pocket in the engine. If so you will see air bubbles at the radiator neck while the engine is running. Distilled water can be hard to find. Most stores don't have it anymore. I've been getting it at Frys.

Still having cooling system issues. I've removed the thermostat and am running the bike without it to see results. I got a good seal on the thermostat compartment so was hoping for the best. After checking all hoses and flushing out the radiator using a flush product I reassembled the bike completely hoping for the best. I filled the radiator with anti freeze then let the bike idle for 20 minutes then added more fluid. As i was securing the newly painted muffler shiel I noticed the dreaded drip. Some how antifreeze was leaking from the radiator and filling the channel at the bottom of the radiator. I looked at all hoses and all where fine. The radiator has not leaked before so I'm thinking when I resecured it I might have damaged it somehow by maybe too tight on the three screws? The backside of the radiator seems to be getting wet and pooling at the bottom. But it's only the fan behind it and no hoses so maybe I've damaged it? Since it still had fluid I took it for a test ride and then the temperature light activated even without a thermostat. When I got home anti freeze was all over the muffler and the engine appeared hot and steaming. So the more I try, the deeper this problem gets. I guess tomorrow I'll look closer for a leak before removing and examining the radiator. Any suggestions anyone? At least by now I can disassemble the plastic on that bike in short work. Also this would be the first testing of fluids with no thermostat shut closed?

Back up here a minute, You ran it without the thermostat filled with distilled water for a good amount of time, and your trouble light went off? Then what?

Yes. I'm having a problem with a Yamaha 2006 Vino that I recently purchased to fix up and sell. I discovered I had a problem in the water cooling system because after a mile or two the temperature light would activate. When I purchased the bike after I ran it a bit I discovered it was bone dry.
Anyway, yes currently I'm testing the cooling system without the thermostat and never using water but flush product then antifreeze. Same result temp light activated and now radiator appears to be leaking.
Today I tested the thermostat in very hot water and it opened.
I'm draining the radiator to remove for the 3rd time for a close inspection.

I appreciate your thoughts on this. Thank you.

While the radiator may be leaking, it's also possible that a connection near the top of the radiator is leaking, and coolant is running down from there. Or it could be the pressure cap is opening, either because pressure in the system is too high, or the cap is defective, and coolant is coming out from there. A new radiator is still available for $75. It would be nice to have a service manual for it.

49ccscoot has the manual.

Thank you for the 2006 Vino manual. It was very easy and quick to open up in the link I was given and I had no problem printing the pages I needed. Thank you.
Today I removed the radiator and plugged all the outlets except for the main cap. At first it appeared to have no leakage, but when I double checked by putting a second try of fluid in, it began leaking. So I will be ordering a new radiator. Maybe I'll first try our Wanted forum?
Thanks everyone.
Joe in Carefree,AZ.

You can get a new radiator from here

https://www.partzilla.com/catalog/yamaha/scooter/2006/vino-50-xc50v/radiator-hose

I get pretty much all my Japanese bike parts from here. All my bikes are too old to get parts from a dealer anymore.

Remove your sensor, and compare it to this one: https://www.ebay.com/itm/233794317739?hash=item366f3a2dab:g:QfEAAOSwaKpiCjMW&amdata=enc%3AAQAHAAAA4Dt9T0zigSs7s%2BpRoGWt3ODGqJOQb0yweN%2BYoEAOG1rnwiI29howQTWh%2Fruzzpv3fnSvDhFKeR8idry51uwv9nNHN2jAYmepD6n9hSWLNoRamvDGdv%2BKSLJq8uQ8PbzdfJ5Z304PHWfzfPEfX8IIu9uYaPFTsnzgi8jiq3%2B8xWWnZhe1JrX6a36u7DLvlsCDPdeZjSi5BenMIZtmiC2aDCKvSzZJ79nThAUtxDp4B05zOzdCFi%2B5XYRGkJBgXhHyJ2swh9PKj2gTFeJn54%2BDknefgR8fRYPH9YsBe7reSY4q%7Ctkp%3ABk9SR9Tpt_fNYQ

I'd look on ebay, and try to avoid paying Partzilla prices for the sensor.

Hello All, I've posted a request for a replacement radiator in our forums Sale/Wanted catagory. You might give it a look.
Thank you,
Joe in Carefree,AZ.

Pull your radiator and take it into a small radiator shop. They might fix it for less than a new one, and have it back to you by the end of the week. I'm sitting on a complete C3 (same radiator as the Vino) theft recovery w/ 3,600 miles. I haven't picked engine parts off it yet, cause I'm not quite sure what I'm doing with it.

I did not know that radiators could be repaired. Thank you, I will follow up on that.
Did you get your theft rebuild scooter from auction?

I bought this on FB marketplace last summer. I've owned a dozen C3s since 2011 when I bought my first one. My current daily is a 2007. This is a 2009 w/ clean VIN and a little over 3,000 miles. My previous daily was a 2008 that I sold with 36,000 miles on it. When I switched scooters, the insurance went up $70 a year from the 2008 model to the 2007 model. At some point I'll switch it all over to this frame and lower my insurance. I only have 15,000 miles on my current C3, so that day is a ways off.