2006 Yamaha Vino XC50 starts and quickly dies

[Lou]

Hi there --
I've had my Vino for about 6 years. 2 years ago I was riding it and it bogged down. I put it in the garage and didn't take it back out until about a month ago. 

I started by replacing the radiator fluid. Then I removed the carburetor and took it apart.  I opened the bowl and removed the screw that was holding down the float pin. I had a heck of a time getting the float valve out. I had to pull quite a bit on the float to remove it. It was covered in green stuff which almost looked waxy. 

I cleaned the carb, and then I replaced the float valve with the same OEM one. I reused the float as the kit didn't come with a new one. 

I reinstalled on my scooter and kick-started it -- it started surprisingly easily and continued running -- however, gas was pouring out the bottom of the carb. I figured I needed to redo the float adjustment. I ordered a new OEM float. 

I took it apart again, and replaced the original float with the new one. 

A couple notes:

• I had an extremely difficult time releasing the Throttle Position Sensor connector. really difficult. I did a LOT of pulling. 
• when cleaning the carb, i pulled off the Throttle Position Sensor (at the time I had no idea what it was). I put it back on and made sure that the throttle could still move freely. 
• My electric start wasn't working and I had determined that it was the handlebar start/stop unit. I replaced it with an OEM new one. 
• in trying to figure out why my electric start wasn't working I cleaned all the electric connectors. 

I reinstalled the carb on my bike and tried to start it with the electric starter -- the starter was working, but it wasn't starting (if that makes sense). I moved on to kickstarting it and then I rolled the throttle. On the next kickstart it started then quickly died. I did this over and over -- squeezed brake, rolled throttle, kickstarted it -- it caught then died. 

I checked to make sure I  hadn't confused a vacuum line with the fuel line; I hadn't. 

I removed the carb again, took it apart and cleaned it again. I put it back on the bike and had the same problem as before -- i could get it to catch if I rolled open the throttle, but then it would quickly die. 

Here are things I'm wondering:

• could I have messed up the throttle position sensor and this is the result?
• could my float still be incorrect? 
• In changing the handlebar start/stop unit could I have done something to the throttle cable? (Though in checking it it moves freely)

Thanks for any help. 

[steve1297]

Did you replace the jets in the carb? Sounds like your idle jet could be clogged...
Just replace both jets. You're having to give it gas to start it because it's not getting enough with just the idle jet.

[Lou]

Thanks, steve1297 I will give that a try! The kit I got only had one of the jets (the main jet) in it. I sprayed compressed air/cleaned the jets with carb fluid, but I will do again when I take it apart for the third time -- I may also see if I can buy replacement jets on partzilla. 

[steve1297]

If that idle jet is clogged, you'll never get it unclothed. You should be able to find jets on ebay.

[Lou]

I replaced the jets. I cleaned the carb again. I also replaced the fuel line that comes from the petcock with a tygon clear fuel line. I also tried to kickstart with the fuel line disconnected from the petcock -- fuel does squirt out of it when I kickstart it.

I had replaced the spark plug with a new one. My next step will be making sure I have spark.

Also, I have a new battery but I have tried using the electric starter so many times that I am sure I have drained it -- could this affect it starting? I always thought you didn't need a charged battery to use the kickstart?

I do have the service manual and I will be going through the troubleshooting steps again.

[steve1297]

Some CDI use the battery to produce spark. But if it's starting for a second...
Check to make sure you have spark. Disconnect plug wire, put a plug in the end of the plug wire. Touch end of plug to engine, and turn electric start. You should see spark.

It sounds like a carb issue. Could be the diaphragm or something. You can mess with it for days, or buy a new one for $15.