Hey gang,
OK, I have a 2006 Yamaha 350 Bruin 4-stroke ATV...
It's seen fairly regular use for most of the time I have had it (bought it new).
I had previously never run the gas out of it, cause I was using it a lot...
About 3 months ago, I knew that I wouldn't be using it for a while, so I ran the gas out of it before storing it...
I just pulled it out and tried to run it, and it won't run without the choke on, and it won't get past about 1/3 throttle before it starts to sputter from lack of fuel (i'm guessing, seems like fuel starvation).
I pulled the carb, cleaned it all out, (It was spotless inside). Put it back on, same thing....
I ran a can of seafoam through a tank of gas on it while puttering around the best I could... stil no change.
While messing around with it, I put my hand over the throat of the carb (with the air filter out), and blamo! I could rev it up no problem (by restricting the air flow)... hmm seems like its losing vacuum or getting too much air...
There is a vacuum controlled throttle plate inside the carb, (goes up/down), besides the typical butterfly... this plate seems to work off vaccum as it has a hose on it that runs to the front of the throat of the intake.
The air cleaner housing goes up under the cowl, and is just an open hole at the top (kind of like a tube). If I take and stuff it full with a rag, the ATV seems to run just fine... (because I am severely restricting the airflow). It will run with the choke fully off, and while it doesn't have "quite" the top end it did without the rag (when it was running right), it's darn close...
Seems like at idle it is back charging air through the intake a bit, then creates the vacuum as you increase the throttle... (can feel it with my hand over the throat of the carb tube). Is there some sort of "vane" like in a compressor that could have gone bad? or do you think it's still something in the carb? (I would liken it to an air compressor where one of the vanes has gone bad, and is discharging when it shouldnt).
I know tons about cars, but diddly about motorcycles...
Is there something "mechanical" in the engine that can cause this? (I have kept up with the maintenance on it regularly).
So my question is, any idea what could be wrong???
OK, I have a 2006 Yamaha 350 Bruin 4-stroke ATV...
It's seen fairly regular use for most of the time I have had it (bought it new).
I had previously never run the gas out of it, cause I was using it a lot...
About 3 months ago, I knew that I wouldn't be using it for a while, so I ran the gas out of it before storing it...
I just pulled it out and tried to run it, and it won't run without the choke on, and it won't get past about 1/3 throttle before it starts to sputter from lack of fuel (i'm guessing, seems like fuel starvation).
I pulled the carb, cleaned it all out, (It was spotless inside). Put it back on, same thing....
I ran a can of seafoam through a tank of gas on it while puttering around the best I could... stil no change.
While messing around with it, I put my hand over the throat of the carb (with the air filter out), and blamo! I could rev it up no problem (by restricting the air flow)... hmm seems like its losing vacuum or getting too much air...
There is a vacuum controlled throttle plate inside the carb, (goes up/down), besides the typical butterfly... this plate seems to work off vaccum as it has a hose on it that runs to the front of the throat of the intake.
The air cleaner housing goes up under the cowl, and is just an open hole at the top (kind of like a tube). If I take and stuff it full with a rag, the ATV seems to run just fine... (because I am severely restricting the airflow). It will run with the choke fully off, and while it doesn't have "quite" the top end it did without the rag (when it was running right), it's darn close...
Seems like at idle it is back charging air through the intake a bit, then creates the vacuum as you increase the throttle... (can feel it with my hand over the throat of the carb tube). Is there some sort of "vane" like in a compressor that could have gone bad? or do you think it's still something in the carb? (I would liken it to an air compressor where one of the vanes has gone bad, and is discharging when it shouldnt).
I know tons about cars, but diddly about motorcycles...
Is there something "mechanical" in the engine that can cause this? (I have kept up with the maintenance on it regularly).
So my question is, any idea what could be wrong???
