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Discussion Starter · #1 ·
So ive had a couple breakdowns and it seems to keep happening, i have no idea how to diagnose, and as soon as i get any ideas on how to attempt, it starts functioning as normal again. Now i have it sitting at the house and im kinda worried to go back out on it.

This is what its doing. (Mainly happens after getting gas, 87)

Ill be driving down the road and itll be firing right and all is well with the world, then suddenly, the power to the wheel cuts, it wont start back up while running, so i am forced to pull over, then it WILL generally crank, begrudgingly, but as soon as ANY throttle at all is applied, it dies immediately before any audible raise in the rpms.

Im thinking something may be gumming up the Carb? I added some STP fuel treatment and got a little more throttle response, but it would bounce back and forth every couple minutes from fully functional to dying on throttle application.
I also checked the air filter, and visably looks clean, but there could be some dust in it i guess? Once i put it back on and started it, it was responsive and running, but with its track record that may just be a fluke.

Any ideas or help would be appriciated. Thank you.
 

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Discussion Starter · #3 ·
How would i check for rust inside the tank?

i wouldnt think so, i bought it from a weekend warrior and it was garage kept. He was the only previous owner.
 

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Ace Tuner
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Ill be driving down the road and itll be firing right and all is well with the world, then suddenly, the power to the wheel cuts, it wont start back up while running, so i am forced to pull over, then it WILL generally crank, begrudgingly, but as soon as ANY throttle at all is applied, it dies immediately before any audible raise in the rpms.
First I would check the condition of fuel in the carburetors by draining the fuel bowls into a catch can. Use a glass container so you can see if water or debris sinks to the bottom of the container. The 2007 year has main jet fuel cut solenoids so each fuel bowl has two drain screws. Can't remember for sure but I believe you can get to the drain screws without removing the fuel tank.
If fuel in the carburetors appears to be good then it could be running out of fuel while riding.
I'm thinking maybe a plugged fuel filter, faulty fuel pump, blocked tank vent or trash / rust in the tank blocking fuel flow. Next time it dies on you immediately turn the ignition switch off than open a fuel bowl drain screw to check if you have fuel in the carburetor/s.
After it dies do you hear the fuel pump working?

S F
 

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Sounds like a fuel delivery problem, fuel pump, fuel pump wiring, fuel filter clogged, something like that. Carbs would probably stay clogged if they were clogged, not work then not work randomly.
 
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One thing you could do is to wait until it dies and won't start then give a quick squirt of WD40 into the carbs and crank it. If it tries to fire and run it is definitely a fuel problem. If it doesn't it is electrical or more unlikely - air. I am leaning towards Hog's sugesstion of a venting problem.

STP fuel treatment is good but isn't a real cleaner, great for fuel system maintenance tank to tank though. Seafoam is a good cleaner once or twice a year. If you treat a tank of fuel with that it will help clean gum and deposits from the fuel system more efficiently. The bike will stink and may have some grey smoke from the exhaust but I have always had good results.
 

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V-star could be anything from a 250cc to a 1300cc motorcycle :unsure: you say it has a carburetor, we are guessing if it has a fuel pump or not and if your carburetor is gummed up you take it apart and clean it, there is no such thing as mechanic in a can, or at least not one that actually works. Your carburetor is constantly full of solvent, you add fuel treatment in there and all you are doing is adding more solvents. If you own anything with a carburetor you might better learn about cleaning carburetors, you are going to need to do it regularly if not seasonally.
 

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You say the air filter looks clean? How old is it, did you hold it up to sunlight to look through it and have you tried to blow it out with compressed air like it says to do in the service manual?

... it's not running out of air anyway, it's running out of fuel from the way you described it.
 

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V-star could be anything from a 250cc to a 1300cc motorcycle :unsure: you say it has a carburetor, we are guessing if it has a fuel pump or not and if your carburetor is gummed up you take it apart and clean it, there is no such thing as mechanic in a can, or at least not one that actually works. Your carburetor is constantly full of solvent, you add fuel treatment in there and all you are doing is adding more solvents. If you own anything with a carburetor you might better learn about cleaning carburetors, you are going to need to do it regularly if not seasonally.
Most common Vstar is 650 and 1100 and both have fuel pumps, not sure about the others but I suspect most do.
 

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My wild guess is a 125cc based on carb (singular form) but it's just a guess and I suspect a small engine like that might have a vacuum operated fuel pump instead of a little electric aquarium pump like the bigger ones had.

First thing he should do is find a service manual and memorize it.
 

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Discussion Starter · #15 ·
It's a 650.

I'll load test the battery and test the venting problem when I get home. I just bought a battery for my other bike I might yank if that's the issue.
 

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Discussion Starter · #16 ·
When I broke down I did try to get it started so long I killed the battery, but a tow truck driver jumped me off and it fired right up and I managed to get home.
 

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V-star could be anything from a 250cc to a 1300cc motorcycle
My wild guess is a 125cc based on carb (singular form) but it's just a guess and I suspect a small engine like that might have a vacuum operated fuel pump instead of a little electric aquarium pump like the bigger ones had.
Under the title of the thread there is a tag that says.. 2007 yamaha v-star 650
That is how I knew this model has main jet solenoids.

@DunnoWatImDoing Always include year model and bike model in text. Avoids confusion and waisted effort. (y)

S F
 

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So ive had a couple breakdowns and it seems to keep happening, i have no idea how to diagnose, and as soon as i get any ideas on how to attempt, it starts functioning as normal again. Now i have it sitting at the house and im kinda worried to go back out on it.

This is what its doing. (Mainly happens after getting gas, 87)

Ill be driving down the road and itll be firing right and all is well with the world, then suddenly, the power to the wheel cuts, it wont start back up while running, so i am forced to pull over, then it WILL generally crank, begrudgingly, but as soon as ANY throttle at all is applied, it dies immediately before any audible raise in the rpms.

Im thinking something may be gumming up the Carb? I added some STP fuel treatment and got a little more throttle response, but it would bounce back and forth every couple minutes from fully functional to dying on throttle application.
I also checked the air filter, and visably looks clean, but there could be some dust in it i guess? Once i put it back on and started it, it was responsive and running, but with its track record that may just be a fluke.

Any ideas or help would be appriciated. Thank you.
(on our 02 650 V-Star), First; gummed up carb's happen when gas is left to sit & then evaporate from the float bowls, an "age old" carb bike predicament. Symptoms are hard start & poor/no idle. You say bike running fine & then...

Our bike had intermittent stalling, sometimes no re-start, then after several occurrences: no start. Found weak spark @ rear cyl. After some research, replaced "pick up coil" (sometimes called "pulse generator") our problem solved, it was electrical and a little bit tricky repair due to thread locked screws holding pick up coil to inside of engine cover.
For '07, pick up coil is attached to stator, not a separate part.
Note, V-Star forum may be helpful, also. MY $.02;)

650 V-Star pick up coil failure is relatively common. Trouble shoot. Good Luck.
 
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