kz1000j petcock

it works good, but there is a problem gas not enough for engine wants. 1gear rpm coms 8000-9000rpm but not good acceloration and i take it to 2.gear its acceloration comes down and engine lttle bit coughing to 5500-6500rpm. i dont like its acceloration performance and the last speed of it, i solved the problem; gas comes not enough to carburetor.i adjust float height-gas level in carburetor.when i turn the petcock pri position its little better but not much changing.
does the reason of it petcock or some thing else?
and i didn't find the fuel tank air vent,where is the fuel tank air vent?

Could test run with gas cap ajar. Issue will either improve or remain the same. If issue remains the same, it likely results from something else besides the cap vent.

Good Fortune!

Petcock filter screen could be clogged.

Petcock could be clogged internally.

Fuel line or filter could be clogged.

Petcock vacuum diaphragm could be cracked or leaking, thereby not opening fully.

Vacuum line could be cracked or leaking.

As Patton pointed out, the vent is in the cap.

Are you sure the problem is fuel-related and not electrical?

yes, i m sure.

Your fuel line may be reacting to the gas/alcohol mix by swelling up restricting the flow. Try replacing the lines with alcohol tolerant ones if possible.

I believe the Honda dealers may carry alcohol tolerant fuel lines.

i tried; its same

i changed the fuel line.

i am thinking about the fuel level in the carburetor; i guess it is not coming to normal level....

If not already done, would use an ignition timing light to assure proper function of the advancer, by watching the advancer quickly move back and forth as rpm is varied by blipping the throttle.

If the advancer is stuck, it should be lubed, or both cleaned and lubed.

Good Fortune!

kawastrtfgtr wrote: i am thinking about the fuel level in the carburetor; i guess it is not coming to normal level....

If not already done, would perform the clear tube test to determine fuel levels inside the carb float bowls.

Good Fortune!

i did, its ok i will look the advancer

pull advancer off and grease it with dielectric grease. mine was stuck solid. runs much more better