Drinking to much fuel and looses power on high rpm.

[Zobaer8686]

Hi
Recently I have tuned up my cb750f with new pod filters and changed the jets to 35 to 40 and 115 to 125. Raised the needles with 1 shims. Megaphone exhaust. Now it’s drinking fuel like hell. Consumed 5 litres fuel in just 6 or 7 kilometres. Please advise what to do.

On the other hand after 6 to 7k rpm it’s struggle and looses power.
Looking forward valuable advise.

 

[dirtdigger]

Well everything you did will increase fuel usage. What did it actually need for jetting? Put everything back to stock except I would probably start with 120 main jets. Then while riding, I use highway speed......hold the throttle wide open and see how it runs....if it starts bogging down slowly close the choke....if it picks up and runs better it is lean, if it gets even worse than it is too rich. Adjust jetting as needed. Then do the same thing but try a couple of different throttle positions like 1/4, 1/2 and 3/4 throttle as see how it runs and use choke to determine if its rich or lean and then adjust needle as needed. I very rarely find the need to up the idle jets even with big bore motors.

 

[Zobaer8686]

Well everything you did will increase fuel usage. What did it actually need for jetting? Put everything back to stock except I would probably start with 120 main jets. Then while riding, I use highway speed......hold the throttle wide open and see how it runs....if it starts bogging down slowly close the choke....if it picks up and runs better it is lean, if it gets even worse than it is too rich. Adjust jetting as needed. Then do the same thing but try a couple of different throttle positions like 1/4, 1/2 and 3/4 throttle as see how it runs and use choke to determine if its rich or lean and then adjust needle as needed. I very rarely find the need to up the idle jets even with big bore motor

Will follow your instructions and come back. Thanks for the advise.