Motorcycle Repair/fuel milage


I know you do virago and its a yamaha but i have a 2005 yamaha roadstar 1700. my problem now is bad fuel mileage. on a whole tank on the highway 90 miles and forget the city right now a half a tank is 30 miles..
changed stock filter to k&n, re-jetted carb with the dynojet kit and pipes to cobra slip ons. i know i'm supposed to loose some mileage but.......
more history
started loosing power only when i tried to go past 70mph if felt like i was pushing it. i thought it needed to be jetted a gain , they did it maybe an improvement but no go(mileage still good). then another guy told me its the clutch changed that and still no go. went to another guy and he said the manifold is crack and sucking in air, changed that and the bike has its power back but the now the bad gas mileage. so forums are say wrong jets and so can you please at least guide me in the right direction.  
p.s. also what happens now if i'm at a high speed and i back of the throttle its almost feels like im braking without braking or hesitating...lot of info i hope.
thanks tony

OK. It sounds like the bad Manifold was the cause to begin with.
The re-jetting you had done the second time might have been copensating for the
vacuum loss. And now the manifold is fixed, its now running to rich.
I think replacing both the manifolds and O-rings would be Best.
Then go back to the Original DynoJet Setup. E-clip back were it was per Instructions and the Main Jets also Listed in the Dyno Instructions for Modified or Slip on Exhaust.
Test for Vacuum leacks with a few burst of starter fluid around the manifolds and throttle blade shaft seals.  

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william joseph stack


I specialize in Virago carburetors. Internal parts sizes, Needle and jet sizes for each and every year and model. Hitachi and Mikuni. I also can give tech support and Tech Support for carburetor problems and issues. Carburetor tuning and syncronization. Carbburetor rejetting and dynojet installations for engine modifications. I know every needle and jet size for every Virago made. I have done over50 Virago carb Salesand Rebuilds in 2012. I have over 50 sets ofVirago carbs in stockright now. I Build, Ride and Breath Virago. I have both the 1983 Midnight Virago's. The XV750MK and the XV920MK. 1 of my 1981 XV750H is is Premier Cycles, Billy Joel's Bike Museum.... I am an Honest and Fair man. I am also a Finicky Perfectionist withmy carb work. Ihave all the obsolete hardto find carb parts. I have new diaphragms, new floats, I have the float level setting down to an art. I have fabricated transparent bowls for both version 1 and version 2 carburetors.


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