Stella 125 Automatica CVT
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Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Thu Feb 07, 2019 3:44 pm quote
I picked up a Stella cvt for free which isn't running great. I figure I'll start this thread to track my issues and solutions as i progress, since there isn't much info out there about these models. Issues noticed right off the bat is an ecu warning for engine temp sensor which seems to be common and not critical to running. I bought a replacement anyways but never installed cause it required removing engine from frame.


First steps to get it running...cleaned the carb, changed the air filters and fuel filters and got it running for a short period. Drove it around for half an hour and it smelled like burning plastic. Took it back to my garage and shut it down and it wouldn't start again.

So then i tried replacing the ht coil which i assume was the burning plastic smell. This led it to start again and run on kickstand for half an hour. Next, i tried to dial in the carb correctly, attached a cheap tachometer and set it to what the idle the service manual said to. Then messed with the idle adjustment screw following next steps of the manual. Then moved on to the air fuel mix screw step in manual. At this point the idle went haywire revving uncontrollably fast. So i turned it off and reset it. After that it wouldn't start again for weeks.

I figure it is a little bit of a carb setting issue and possibly something else like valve clearances. This week went back to messing with it and got it to start again by opening up the air fuel mix screw slowly until it started, but idling strange still. Once it warms up it either dies or revs really high to the point of sliding the scooter on its kickstand along the ground.

Next i went to check compression but given the awkward placement of the engine shrowd, i lost the compression test spark plug hole attachment into the ether of the magneto fan. This required removing the engine from frame to take the engine cover off. So this is where I am currently at, with the engine out of frame, shrowd off and recovered that stupid brass part!

Now that engine is out and accessible, i decided to check valve clearances and replace that engine temperature sensor. Service manual says to align the marks on the cam sprocket parallel to the open case where the head cover goes on, then make sure the marks on the magneto line up with the Mark on the engine case. I've got it lined up on the cam sprocket correctly and have checked the clearances, which the inlet valve is a bit loose, and the exhaust valve is a bit tight. Unfortunately the marks on the magneto are strangely not exactly where they should be. There are 4 marks on the magneto in two groups of two. When the cam sprocket is lined up correctly, there are two marks on the magneto at 12 o clock, and two near the engine case mark around 10 o clock, but they are about half an inch above the case mark which is at about 9 o clock. Those two marks closest to the case mark have labels, one is "r" (which is the further away closest to midnight) and one that is marked "t" which is closest to the case mark. I am wondering if these can be/need to be set correctly in line with the case Mark and if so, which one goes at that mark.

Either way, for now i will adjust the valve clearances to spec.

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Frame with no engine!

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engine extracted!

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fan cover off. Brass part rescued from the ether.

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New engine temp sensor installed. Just gotta find a solution for the snap connector to the sensor cable. This replacement came bare no connector.

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Who would have thought this scoot is only 4 years old, from the look of that pipe. Lived all its life outside on the streets of nyc.

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cylinder head cover removed.

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another view of the internals.

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Cam sprockets lined up correctly for valve clearance check.

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marks on the magneto.. one set of 2 at the top, one set of two around 10pm just above the case mark. the top mark on the magneto left says "r", the bottom one says "t". neither line up correctly with the case mark.



Last edited by swiss1939 on Thu Feb 07, 2019 8:17 pm; edited 2 times in total
Ossessionato
73 Rally, 74 Rally, 76 ET3, 80 P200, 63 Li125, 65 Li225 Silver Special, 86 Elite 80, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 2996
Location: Oceanside/ SF
Thu Feb 07, 2019 4:26 pm quote
Ive never seen one of those close up. Looking forward to your pics.

If its carb’d and revving sky high have you checked for air leaks at the carb, manifold, or exhaust? If its anything like a smallframe vespa with those 3 bolting to the cases, it may be worth putting some semi liquid gasket sealant at any possible air leak points.
Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Thu Feb 07, 2019 4:30 pm quote
Parts are scarce for it which sucks. Definitely needs a new exhaust and exhaust down pipe as it's only 4 yrs old and they are rusted like a 30 yr old pipe. I was questioning the integrity of the vacuum hoses and am gonna replace all the hoses while everything is out of the frame.
Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Thu Feb 07, 2019 8:05 pm quote
So this scooter also has a fuel resevoir tank at the base of the seat, above the gas tank. The way it works is the fuel gets fed through a filter up from the tank to the resevoir with a pump, once up in the resevoir, it is gravity fed from the resevoir down through a filter to the carb. The resevoir has an overflow that feeds back into the gas tank filling neck, so that the pump keeps filling the resevoir, regardless of if it goes to the carb or the overflow back into the gas tank. I guess it's something to do with consistent flow of fuel, cause the fuel pump spits it out in a pulsing stream instead of constant flow.

This resevoir does have some white corrosion around the base, which makes me wonder if maybe the resevoir tank has a microscopic leak? One thing i've noticed about this scoot that I haven't figured out yet is there is some dampness along the side of the tire and ground below the engine that looks to be some sort of non water soluble fluid. Its like a spray bottle misting the surface of the tire and ground. This wet area then crystalizes when dry, so that the ground and tire have a white crystal coating on it after sitting in one spot for the past couple months. I'm hoping its related to the white corrosion on this resevoir tank but who knows!

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fuel resevoir tank corrosion.. is it a leak?

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another view of the white corrosion at the base of the fuel resevoir.

Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Thu Feb 07, 2019 8:11 pm quote
And here is a list of other cosmetic and non engine related issues when I received it. All need to be resolved, but am preoccupied with getting the engine issues sorted out first.

1. all locks were destroyed as the original owner had it parked outside on the streets of nyc for its whole life. The glove box latch and lock were destroyed, I fixed that already. I tried to install the ignition lock but put it in wrong direction which prevented the steering lock from turning correctly, so I had to drill that new lock out, and just haven't put the other new one in yet.

2. front shock is worthless. On my first and only ride with this scoot, it bottomed out on every bump. New shock already received and waiting to be installed.

3. chrome trim on the leg shield was ripped up on one side, again most likely from someone messing with the scoot parked out on nyc streets. Black plastic trim in hand waiting to be installed.
Ossessionato
73 Rally, 74 Rally, 76 ET3, 80 P200, 63 Li125, 65 Li225 Silver Special, 86 Elite 80, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 2996
Location: Oceanside/ SF
Fri Feb 08, 2019 9:22 pm quote
You’ll know if your valves are set correctly when you try to start it. If it runs then you found TDC and adjusted accordingly.

Does the fuel pump run off a vacuum created by the piston? I know the vacuum fuel taps run off suction. The pulsing fuel could be in time with the stroke.

Was there any battery acid spilled by that reservoir? Maybe its just NY oxidation from being outside?
Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Fri Feb 08, 2019 11:16 pm quote
I believe the pump does run off vacuum from the head. As far as battery acid spilled by the reservoir, no clue. I wanna say I doubt it's battery acid as the battery is nowhere near it, but it could be some liquid spilled or pooled there over time given how the under seat engine cover wraps around the reservoir which sticks out. Possibly salt from melted snow and street salt over years.

The guy I got it from was original owner and really was hands off owner, didn't care much to elaborate on service other than he had it serviced and just didn't want to deal with it anymore with the issues it had, basically just wanted it gone. All I cared about was "free" and the valid paperwork was there!
Member
2005 Stella 2T, 2014 Stella 125 Automatica
Joined: 20 Jul 2018
Posts: 39
Location: NY, NY
Sat Feb 09, 2019 9:56 am quote
I figured it best to stick with lining up the T mark on the magneto with the case mark, and the cam sprocket marks would lay wherever they are at that point. This seems to be the correct TDC point as once I set everything there, the cam sprocket marks were lining up with the ground instead of the angled head case. Inlet valve clearance was a bit loose and the exhaust valve was too tight. These are the correct settings versus what they were at when checked.

correct:
Inlet - 0.08mm +/- 0.01mm
Exhaust - 0.10mm +/- 0.01mm

actual clearances as checked:
Inlet - 0.10mm
Exhaust - 0.08mm

These have been corrected. Hopefully those minor changes make a huge difference in how this runs.

The engine temp sensor wire has a snap connector that I am trying to find a mate for, to wire up to the new temp sensor which is bare wires. Anyone recognize this connector pictured, and or where to get something like it?

IMG_20190209_123359.jpg
original connector next to the new sensor bare wires.

IMG_20190209_123410.jpg

IMG_20190209_123436.jpg

Ossessionato
73 Rally, 74 Rally, 76 ET3, 80 P200, 63 Li125, 65 Li225 Silver Special, 86 Elite 80, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 2996
Location: Oceanside/ SF
Mon Feb 11, 2019 4:17 pm quote
No idea where to find that exact quick connector. Since youre not messing with it all the time i'd say cut and solder in some common spade connectors in case you ever need to disconnect, or just solder the wires together and insulate it.
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