[650CB]

Title is pretty self explanatory. I have a 83 CB650 that starts and runs, however it is taking around a gallon of gas to go 10 miles, and it struggles to do 60mph in 5th gear. Bike has just under 30,000 miles Carbs were professionally rebuilt like 200 miles ago, do not leak, brand new fuel petcock 20 miles ago, can not find a fuel leak in the fuel line or tank. Only thing wrong is that the valve cover gasket leaks at the little indents at the head of each cylinder( there are little plastic looking inserts where the surface that the valve cover sits on drops a little). I replaced it, and it still leaks, so maybe I need to gasket-maker those indents? But still, fuel should not be getting up there in the first place right? Any ideas? Thanks

 

[rustysavage]

How do your spark plugs look? Does the exhaust look good or funny at all?

 

[wadenelson]

Hows the oil level? Does it seem to be high, as if gas has diluted the oil?

Did you insert a new, clean in-line filter between the tank and your newly rebuilt carbs? What? Why not!

See it all the time, crud and crap in the tank contaminating a fresh carb rebuild. Piece of rust or crust prevents float needle from seating, bowl overfills and excess fuel runs into the engine through overflow tube or passageway in carb.

The ONLY ways to get 10mpg are for the choke to be stuck on (running rich, black fluffy spark plugs) or fuel pouring through the motor (oil level high, rich running).

 

[650CB]

Hows the oil level? Does it seem to be high, as if gas has diluted the oil?

Did you insert a new, clean in-line filter between the tank and your newly rebuilt carbs? What? Why not!

See it all the time, crud and crap in the tank contaminating a fresh carb rebuild. Piece of rust or crust prevents float needle from seating, bowl overfills and excess fuel runs into the engine through overflow tube or passageway in carb.

The ONLY ways to get 10mpg are for the choke to be stuck on (running rich, black fluffy spark plugs) or fuel pouring through the motor (oil level high, rich running).

Seems to be a carb issue from what I can tell. Plugs are fine, no fuel in oil, or vise versa, so I will pull apart the carbs and look at them. Thanks for all the input

 

[650CB]

So I pulled the carbs off and thoroughly cleaned them again, and adjusted the pilot screws to factory recommendation ( 2 and 5/8ths turns back out from seated position), because they were all about 5 turns out when I took them out to clean them.
I put everything back in and now it has less throttle, and if I rev it, it hesitates and sputters for a second before reving up, and even dies sometimes.

I don't know if it is drinking so much gas anymore however, I guess it could still be. Not sure what the deal is. Also the exhaust pipes on cylinders 1 and 3 have been noticeably less hot than 2 and 4 after the engine has ran for a 10 minutes. Plugs are fine.