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vm28ss...can't get the accelerator pump to work
- seanbarney41
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- '79 kz1000 LTD '75 Honda CB750
Next possible problem...I have removed the tiny clips that hold the check ball and restrictor for cleaning and I have noticed that there is a nearly microscopic groove in the well for the clip. If you get the clip into the groove properly it allows the restrictor and check ball to rattle around in there quite a bit. Is this necessary for the accelerator pump to operate? It seems almost impossible to get the clips back into the groove. Those stupid little clips have been flying all over my shop and of course are then impossible to recapture.
Also, is the pump circuit even of any benefit? Can these carbs be tuned to operate adequately without the pump circuit?
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- seanbarney41
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- loudhvx
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1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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- seanbarney41
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- martin_csr
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To test the accelerator pump the manual says to quickly operate the throttle pulley & check that fuel squirts from each nozzle without hitting the carb bore walls & the quantity ejected from each nozzle should be the same.
Bench testing: the amount of fuel ejected is dependent upon how vigorously the throttle pulley is actuated: slowly = small amount of fuel & quickly/vigorously = a good squirt.
Here's a cutaway diagram of the VM accelerator pump w vacuum sensor.
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- seanbarney41
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- martin_csr
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Since your bike is a KZ1000 & it has had some performance stuff done to it, perhaps you should check further as to whether or not disabling the AP would be the thing to do. ??? I think the pump was added to address a lean condition under heavy throttle or something --->>> perhaps as a consequence of the lean jetting mandated by the EPA. ???
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- Patton
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As Martin suggested, would consider disabling the AP and compensate with non-AP jetting.
Good Fortune!
1973 Z1
KZ900 LTD
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- loudhvx
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martin_csr wrote: ... I think the pump was added to address a lean condition under heavy throttle or something --->>> perhaps as a consequence of the lean jetting mandated by the EPA. ???
That's what I suspected as well.
Jetting richer for acceleration meant it was richer for moderate cruising. So to keep it lean for cruising, they jetted it lean and added the pump for acceleration only.
My buddy's ST ran so much better after he ditched the pump and rejetted.
1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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- RonKZ650
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321,000 miles on KZ's that I can remember. Not going to see any more.
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