Cosa stalling, any thoughts?
Post Reply    Forum -> Not-So-Modern
Author Message
Member
Vespa Cosa 200 1994
Joined: 01 Oct 2019
Posts: 25
Location: Czech Republic
Wed Jul 29, 2020 8:49 am quote
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.

DSC07180.jpeg
rusty beauty

Member
Vespa Cosa 200 1994
Joined: 01 Oct 2019
Posts: 25
Location: Czech Republic
Fri Jul 31, 2020 4:54 am quote
Fuel tap
Could this issue be related to fuel tap? Strange is that it stalls only when engine is warm/hot.
Style Maven
74 50s x3 78 P200 84 Cosa PK50XL2 58 AllState 68 Sprint 80 50special '66(?) Super125
Joined: 22 Nov 2010
Posts: 7799
Location: seattle/athens
Fri Jul 31, 2020 7:03 am quote
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?
Member
Vespa Cosa 200 1994
Joined: 01 Oct 2019
Posts: 25
Location: Czech Republic
Wed Aug 05, 2020 5:52 am quote
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.

WhatsApp Image 2020-08-05 at 15.11.51.jpeg
Dellorto! Btw. Love SIP shop, they are so fast.

Hooked
S150, Cosa LX200, DL1000V
Joined: 02 Jan 2010
Posts: 479
Location: Sunny South West UK
Wed Aug 05, 2020 2:10 pm quote
Good luck!
Addicted
2007 Stella 150
Joined: 02 Nov 2019
Posts: 761
Location: Rochester, Minnesota
Sat Aug 08, 2020 3:18 pm quote
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.
Missouri Loves Company Rally   vespa scooterwest scooter west Motorsport Scooters   Scooter Parts Company
Post Reply    Forum -> Not-So-Modern
[ Time: 0.1332s ][ Queries: 27 (0.0318s) ][ Debug on ]