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Author Topic: rpm related issue. 78 750k  (Read 829 times)

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Offline honda750k

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rpm related issue. 78 750k
« on: July 31, 2009, 05:51:52 PM »
This is a new one to me, althoug I AM new to the points ignition system.  the problem is that when I open the throttle, the bike wont rev when I open the throttle,  it takes about a second or two if it even responds, unless the bike decies to stall.    sometimes, the motor will cut out for an instant, and just wake back up, as though it were dozing off at idle. 

the carbs are nice and clean, synch is dead on, and at idle all 4 are firing, so I'm suspecting the ignition isnt advancing correctly, and as such is causing my issue.

anyone have input?  I'm 100% POSITIVE my synch is precisely accurate, carbs are all clean as can be,  fresh gas and oil, good plugs and hot spark on all 4 with good NGK plugs. not sure if the plug brand matters for the issue, but jsut put it out there.
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These bikes dont die, they hibernate until the right person wakes them up again.

Offline TwoTired

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Re: rpm related issue. 78 750k
« Reply #1 on: July 31, 2009, 06:26:10 PM »
Your bike has an accelerator pump to shoot gas into the carb throats when you twist the throttle.

Is it working?
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline honda750k

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Re: rpm related issue. 78 750k
« Reply #2 on: July 31, 2009, 06:56:26 PM »
is that the one on the #2 carb with a rod going to the throttle cable bracket?  I'm seriously not used to these carbs. at all
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These bikes dont die, they hibernate until the right person wakes them up again.

Offline my78k

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Re: rpm related issue. 78 750k
« Reply #3 on: July 31, 2009, 07:02:34 PM »
Yep that's it...
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Offline taxiscooter

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Re: rpm related issue. 78 750k
« Reply #4 on: July 31, 2009, 07:03:27 PM »
Two Tied is dead on ....I have a 77k7 750 and it did the same thing before an accelerator pump replacement.
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Offline honda750k

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Re: rpm related issue. 78 750k
« Reply #5 on: July 31, 2009, 07:09:47 PM »
ahh crap. I didnt realize thats what that was.  gotta replace mine then. rubber diaphragm is pretty rigid now from sitting for MANY moons.
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These bikes dont die, they hibernate until the right person wakes them up again.

Offline eurban

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Re: rpm related issue. 78 750k
« Reply #6 on: August 01, 2009, 07:23:25 AM »
Do a reality check before disassembly. Take off your air cleaner and whack open the throttle while observing the throats of the carbs.  If the accelerator pump is functioning properly, you will see a stream of fuel squirting down the carb throat from the small brass nozzles located next to the choke plates. . . .It is very easy to check the advance mechanism for proper operation if you have a timing light.  As a minimum pull off the points cover and see if you can twist the advance mechanism. . . .
« Last Edit: August 01, 2009, 07:25:56 AM by eurban »
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