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Kenny O.
Kenny O., Motorcycle, ATV, Mules, Side by Side's Product Specialist. All Brands
Category: Motorcycle
Satisfied Customers: 1021
Experience:  Worked for Kawasaki Motors as a Product Support Specialist (Factory Support) for 24 years
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07 yamaha 125 vino with about 1000 miles. starts fine and

Customer Question

07 yamaha 125 vino with about 1000 miles. starts fine and runs great - always has non ethanol fuel etc. After about 10 miles of riding at 3/4 to full throttle it runs out of gas. Let sit for 20 seconds and it is fine again.
JA: Has the vehicle turned into a gas hog? And how does it start -- same as usual?
Customer: Everything else is fine - just the starving for fuel after 10 or so miles.
JA: What is the model of your '07 motorcycle?
Customer: 125 Vino Yamaha
JA: Are you fixing your bike yourself? What have you tried so far?
Customer: Just getting started
JA: Anything else you want the mechanic to know before I connect you?
Customer: suspect some type of filter or trainer blockage?
Submitted: 2 months ago.
Category: Motorcycle
Expert:  Kenny O. replied 2 months ago.

Hi my name is ***** ***** I speaking to ?, I am the expert.

Can I get the 17 digit frame number that will insure me that I pull the proper documentation for this unit.

When the unit quits is it like turning off a light or do you get an early warning like it starts to break up and miss ?

Obviously its does a lot of sitting with a 1000 miles on it and its a 2007, has the carburetor even been cleaned or removed ?


Customer: replied 2 months ago.
When it stops it slowly and smoothly runs out of gas
Never cleaned carb -BUT always drained of gas when idle in winter and use only no-ethonol + stable
Expert:  Kenny O. replied 2 months ago.

OK thanks Buck, it sounds like its a venting issue and that can be from sitting, the cap vents and there is also a vent that right under the filler cover, the filler cover is if you over fill it channels the spilt gas to the ground.

Under that you'll see a line coming from the top of the tank, there is an elbow on the tank, just down from that you'll see a connector for the hose, simply disconnect that and then go try running (do this for testing purpose only) then if the problem doesn't exist any more then you likely have a pinched vent line or the roll over valve is not functioning properly and needs to be replaced.

Also you can go to your Home Depot, there is a product in the lawn mower accessories area called "Mechanic in a Bottle" works really awesome if you have any stale fuel in the fuel system, its actually dissolves it.

I think this is a good place to start, as I'm pretty sure this has venting all over it.

Let me know if this helps or you have further questions.

Thanks Buck !


Customer: replied 2 months ago.
will try tomorrow AM nd get back to you
Expert:  Kenny O. replied 2 months ago.

Awesome, let me know !

Thanks Buck

Customer: replied 2 months ago.
Kenny ran without the gas cap and does the same thing - so not venting, whats next?
Expert:  Kenny O. replied 2 months ago.

So you ran the unit without the cap ? What about leaving the cap on and disconnecting the vent line on the top of the fuel tank ?

Customer: replied 2 months ago.
Will do
Customer: replied 2 months ago.
What's the difference from taking the cap off?
Expert:  Kenny O. replied 2 months ago.

Well technically it should vent through the vent line, I want you to pull that line with the cap on then that will tell me it might be something else ?

Customer: replied 2 months ago.
Undid vent still runs out of gas
Expert:  Kenny O. replied 2 months ago.

OK good, then the venting doesn't appear to be the issue at this time. So next you need to determine that the carburetor is actually running out of fuel. You stated earlier that you drain the fuel from the carb, so I take it you know exactly where the drain screw is ?

So here is what I would like to know ?

1.) when the engine stops, does it start RIGHT back up, or how long before it will restart ?

2.) so immediately following when it stops, if you can get to the drain screw on the float bowl and open it to see if you get any fuel out of it ? That would tell me in actuality if indeed the float bowl is full of gas or empty ?

Also let me point out that that this unit has a vacuum controlled pet-cock that basically turns the fuel flow on when the engine is running and then shuts off when the engine is stopped, that valve is controlled by engine vacuum, the diaphragms can get old and brittle and then cause problems.

So before throwing parts at it, I think if you can answer the questions I thrown at you that would determine if we need to go in the route of the pet-cock. BTW those are about $18 retail. Also I'd like to mention that I'm not ruling out the possibilities of an issue inside the carb, or an electrical issue in the ignition system ?

Customer: replied 2 months ago.
When it runs out of gas by the time you stop it is running again and acts normal for 1-2 miles then repeats.
Expert:  Kenny O. replied 2 months ago.
OK you say it runs out gas but you really hadn't verified that it actually fuel
deprived? If it's running out of fuel and the engine dies, then your saying that it immediately fills the float bowl back up? That's what I'm questioning, it doesn't make sense ?So here's where I would go with this,
1.) I would pull the carb and inspect and then clean if necessary.
2.) Pull the fuel tank and inspect inside, look at the spigot where the fuel exits the tank, basically looking at the whole path of the fuel from the tank all the way to the carb.Now I'm basing doing all that because it appears to be fuel related or at least a delivery issue ?
Expert:  Kenny O. replied 2 months ago.
Another thing is if you find an external fuel bottle and the just gravity feed the carb, I wanted to throw that at you but not really recommend it as you have to ride the unit, they make gravity fed external gas bottle that all shops use when running bikes on the lifts for diagnostic purposes or syncing carbs on multi cylinder motorcycles.
Expert:  Kenny O. replied 2 months ago.

Hey Buck, if you don't want to pull the carb try going to Home Depot, in the lawn mower section there is a product called "Mechanic in a Bottle" its where the accessories are displayed, try running a rich amount of that additive, I have suggested that in the past on carbureted units with marginal contamination or varnish build up, the stuff is about $5 a bottle, its worth a try.


Customer: replied 2 months ago.
Will try the bottle
Expert:  Kenny O. replied 2 months ago.
Because that would eliminate any possibility of your existing fuel delivery including your fuel tank,
Expert:  Kenny O. replied 2 months ago.
I'm sorry, hooking that external directly to the carburetor
Customer: replied 2 months ago.
Will be tomorrow AM - try the external supply direct to carb - let you know. thanks
Customer: replied 2 months ago.
Kenny I hoped the tank directly to the carb and by passed the device that turns the fuel on. Why not just leave it that way?
Runs perfect.
Customer: replied 2 months ago.
I connected the tank directly the carb
Expert:  Kenny O. replied 2 months ago.
I wouldn't do that because the fuel is always turn on. This is gravity fed and let's say for. Argument sake that something caused the fuel inlet valve to not shut off in the carb, it would basically empty the fuel tank in the engine and the spill over potentially creating a fire hazard, it's not a good idea, those are only about $18 retail, I would not suggest do that.