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Discussion Starter · #1 ·
My fuel consumption has dropped about 10 miles a gallon, getting a hesitation or little jump at low RPMs. Seems like it wants to die at idle
 

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Save them all!
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Do you think you got some dirt or garbage in your tank?

Sounds like you might need to pull the carb.
 

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Very Famous Person
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Why not try something easy like new plugs first. Clean air filter is good. Plugged fuel filter won't change your mileage.

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Colder outside temperatures.
Did you ride this bike last year at this time? Weak spark can require more fuel. Dirty air filter. Anything that messes what happens with the fuel air mix, and what makes it go bang, which includes compression, and how the bang exits.

UK
 

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If you have several cold starts on a tank and the temps are lower, you will get worse average mileage due to more time on the choke or enriching circuit.
 

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Discussion Starter · #10 ·
That I kinda knew, it kinda came on all at once. Yes I rode last year in colder temps actually. Guess I’m gonna have to get rebuild kit for carb.
 

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My 79 Yamaha 1100 is one of the two winter bikes. It gets about 40 mp large gallon. It drops well into the 30 mpg range in the winter, and especially when hauling the side car. It jumped from about 35 to 40 mpg when I replaced a bad connection on the ignition side that send power to the coils.
As a side note, last week it only fired on three cylinders. Replaced the plug on the one that was running cool and fixed the problem.

Hope you get your figured out.

UK
 

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Discussion Starter · #12 ·
I live in Florida, temp isn’t dropping that much to make a difference. Lived in Alabama last winter where it actually got cold, not fun for me. Fuel consumption didn’t change. Something has gone wrong with scoot. Thanx for your input though
 

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Before you tear into the carb, you might consider running a couble cans of Seafoam or Startron thru it. Seafoam for carbs and Startron for fuel injected. Seafoam just might help. But if you've rebuild carbs before with success then you might be okay. I just read over and over where people tear into their carb and end up with a bike that won't even run after. So I suggest something that might clean up the jet mist for a better bang as Krusty puts it.
 

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Couple cans?? One my first, and only halfway. I’ll definitely try that first. Thanx


You might get away with one but sometimes it does take more. I like to be prepared for the worst then relish it not being as bad as it could have been.


Sent from phone.
 

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A filthy air cleaner alone can REALLY affect fuel mileage:surprise:

Winter blends of gas, especially Ethanol laced gas has much less thermal energy and mileage drops.:surprise:

If a plug reading looks anything other than a light tan color then the engine is running rich so it may be the carb needs work. If the 40mm Mikuni or Keihin CV rubber slide diapraghm (sic?) has a rip. hole or tear in it, the manifold pressure won't allow it to move up and down correctly and that can make the mixture rich or lean.

If the cold start choke system is stuck it will cause a rich situation also.

Sam:nerd:
 

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Discussion Starter · #17 ·
Well alright that’s good info there thanx. Noticed tonight that my petcock is leaking now. But at least now some suspicions are confirmed and I have a direction. Thanx all for input. Fingers crossed
 

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Yep, Seafoam won't fix that. Looks like carb job is in order for sure.
 

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The float level can slowly change over time, from all the bouncing. If the arm has bent far enough, the float will allow the fuel to bubble, and spill in to the main entry off the carb.

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