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Discussion Starter · #1 · (Edited)
So iv had my bike now for 3 ish years it's got 23000 miles. it the 04 vn750. I was getting about 40 to 50 mpg average and now I'm getting 13 to 14 mpg after cleaning the carbs and changed the plugs.. the bike runs great has plenty of power and seems to do fine on the road besides the mpg iv cleaned the carburetors before and changed the plugs before and never had this problem until now.. iv checked vacuum sync and pilot screw adjustment and main needle jet highths. Iv checked for vacuum leaks and gas leaks idk what else to check
 

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So iv had my bike now for 3 ish years it's got 23000 miles. I was getting about 40 to 50 mph average and now I'm getting 13 to 14 mpg after cleaning the carbs and changed the plugs.. the bike runs great has plenty of power and seems to do fine on the road besides the mgp
It's either running very rich or the brakes are sticking.

See if the spark plugs are black, with soot in the exhaust.

Brake hoses can collapse internally and hold pressure, have replaced many of those on various vehicles. Back brakes can drag also. With the wheel off the ground, spin the wheel and apply the brakes. Release the brakes and immediately spin the wheel again and see if there's too much drag.

Also check the vacuum hose to the petcock, there should be no gas in the hose. Easier to check this first. ...
 

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It is very hard to imagine mileage that bad. Do you smell fuel at idle? I am not familiar with the carbs enough to know what happens if a diaphragm gets a hole in it but I just went through my carbs and they are so simple it is hard to see how they could get that out of shape. A leak of some kind seems more likely but it seems you would notice that bad of a leak. Any back fire or popping on deceleration? Is the chrome on the exhaust changing color?
 
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