2003 Yamaha Wolverine 350 bogging

[Hasten Haynes]

Idles fine but 3/4 throttle through 2nd gear the atv Boggs and backfires. I’ve replaced carburetor, air filter, spark plug, carburetor boots. Any ideas?

[rdlsz24]

Did it used to run fine? If so, what was done around that time? Fresh gas?

Rob

[Hasten Haynes]

The atv ran fine but I let it sit for a season with gas in the tank so in the previous carburetor it had trash in the carb. So I cleaned it and popped it back on and it was doing the same thing as it is doing now but worse. So I put a new carb on and cleaned the tank and put fresh gas in it. 

[Hasten Haynes]

On 10/2/2018 at 8:42 PM, rdlsz24 said:

Did it used to run fine? If so, what was done around that time? Fresh gas?

Rob

The atv ran fine but I let it sit for a season with gas in the tank so in the previous carburetor it had trash in the carb. So I cleaned it and popped it back on and it was doing the same thing as it is doing now but worse. So I put a new carb on and cleaned the tank and put fresh gas in it. 

[Frank Angerano]

I see you cleaned the tank did you also clean the gas valve at the bottom of the tank ? 

And also make sure the vent at the top of the tank on the gas cap is not blocked. It seems like it’s statving for fuel. What is the air/fuel mixture screw set at ? And has anyone messed around with the main jet needle setting on the carb slide ? 

[Hasten Haynes]

11 hours ago, Frank Angerano said:

I see you cleaned the tank did you also clean the gas valve at the bottom of the tank ? 

And also make sure the vent at the top of the tank on the gas cap is not blocked. It seems like it’s statving for fuel. What is the air/fuel mixture screw set at ? And has anyone messed around with the main jet needle setting on the carb slide ? 

Top of fuel top of fuel tank is clear. Have not cleaned the valve. The screw is set at OEM 2.5 out I’ve played with the main jet setting but it is now back at the middle setting. 

[Frank Angerano]

Don’t be afraid to try and move the clip in all spots and try to see how it operates.  

Also is the float free from any hang ups? 

 

If you are confident that the carb is cleaned, properly reassembled and all good with the fuel delivery then you may have to see if the ignition is breaking down as the engine revs highter.  

Is there a rev limiter on that bike ? 

[Ajmboy]

I was going to say the same thing as @Frank Angerano check the float, almost sounds like it's fuel starved on 3/4 throttle. Sometimes the pins hang up although you mentioned its a new car, so it shouldn't. 

[Hasten Haynes]

On 10/5/2018 at 3:46 PM, Frank Angerano said:

Don’t be afraid to try and move the clip in all spots and try to see how it operates.  

Also is the float free from any hang ups? 

 

If you are confident that the carb is cleaned, properly reassembled and all good with the fuel delivery then you may have to see if the ignition is breaking down as the engine revs highter.  

Is there a rev limiter on that bike ? 

The rev limiter has been disabled