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@bokeh avatar
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Vespa Cosa 200 1994
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@bokeh avatar
Vespa Cosa 200 1994
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Hello not so modern friends

New issue on my Cosa 2.
Morning rides to work are ok, they are mostly downhill and temperature is lower, Rides after work uphill begins to be a problem. After engine has higher temperature, it stalls on full throttle and after it stalls it's harder to start.

I'm not aware of any carb tuning done in the past or recently.

Where should I look first?
- Local bike parts dealer suggested that could be seized a bit and that's why it appears on higher engine temp. (recently I did one longer trip on it - maybe this problem occured after this multi hour ride - lot of full throttle involved)
- Friend suggested it theoretically could be related to some e-choke issues
- Should I just clean the carb?

I wasn't successful with forum search, thanks for your ideas. Btw. this forum helped me a lot in the past when my clutch felt apart.
rusty beauty
rusty beauty
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@bokeh avatar
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Vespa Cosa 200 1994
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Vespa Cosa 200 1994
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Fuel tap
Could this issue be related to fuel tap? Strange is that it stalls only when engine is warm/hot.
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'74 50s x3 '78 P200 E '84 Cosa '91 PK50XL2 - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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'74 50s x3 '78 P200 E '84 Cosa '91 PK50XL2 - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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Strange if yours has a fuel tap, I've only seen Cosas with an electric solenoid valve that shuts off the gas when you switch the motor off. There's a bybass if you open the screw at the back of the airbox cover. Pull the cover off and you'll see what I mean, assuming it's sandard Cosa.

You could rebuild the carb and eliminate any possibility of debris causing partial blockage. At the same time you can check for good flow from the fuel line to the carb. From how you describe when it happens, you might also consider a CHT to know just how hot it's getting on your uphill runs. How does your spark plug look?
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@bokeh avatar
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Vespa Cosa 200 1994
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Vespa Cosa 200 1994
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My Cosa is standard, fuel tap was just a mixture of my bad english and poor googling.
Btw. I made google hot trying to figure out what CHT is
So assuming it's Cylinder Head Temperature, I'll leave it as a last thing to test.
Btw. what would I get to know by measuring CHT?

Parts for carb "rebuild" arrived today, I hope I have all the essentials, Wish me luck.
Dellorto! Btw. Love SIP shop, they are so fast.
Dellorto! Btw. Love SIP shop, they are so fast.
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GTS300, Cosa LX200
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Good luck!
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2007 Stella 225
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2007 Stella 225
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bokeh wrote:
My Cosa is standard, fuel tap was just a mixture of my bad english and poor googling.
Btw. I made google hot trying to figure out what CHT is
So assuming it's Cylinder Head Temperature, I'll leave it as a last thing to test.
Btw. what would I get to know by measuring CHT?

Parts for carb "rebuild" arrived today, I hope I have all the essentials, Wish me luck.
Typically when you get into the 350 degree Fahrenheit region the motor is overheating and will start to seize. You get and indication something is wrong like running to lean and overheating.
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Vespa Cosa 200 1994
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Vespa Cosa 200 1994
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Location: Czech Republic
UTC quote
Carb rebuilded!
So I managed to change most of the gaskets supplied in the dellorto kit for my carb, only few parts I didnt find use for

It starts, it runs, Currently considering riding vespa to work tomorrow

BUT: I found few funny things:

Bonus question, how should I adjust this e-tap screw? https://www.sip-scootershop.com/en/products/adjusting+screw+_23934800 should I just open it as much as possible?
In dellorto kit, the new gaskets for e-tap were smaller so I kept the old ones, to be sure it's tight (there were no sing of leakage anyway)
In dellorto kit, the new gaskets for e-tap were smaller so I kept the old ones, to be sure it's tight (there were no sing of leakage anyway)
Throttle slide is not sliding smoothly and the hook is slightly bent, so now the throttle tends to not to go back. Going to order new hook, but should I order the slide? it's not cheap, I worry the sliding way in the aluminium body is causing the problem.
Throttle slide is not sliding smoothly and the hook is slightly bent, so now the throttle tends to not to go back. Going to order new hook, but should I order the slide? it's not cheap, I worry the sliding way in the aluminium body is causing the problem.
THis is not original, right? I assume it's somethong related to oil mixer (I wish I knew It doesnt mix the oil when I bought this vespa and been riding it for apx.400kms and accidentaly discovered it when replacing damaged clutch)
THis is not original, right? I assume it's somethong related to oil mixer (I wish I knew It doesnt mix the oil when I bought this vespa and been riding it for apx.400kms and accidentaly discovered it when replacing damaged clutch)
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