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Surging at cruising throttle

Old 05-26-2017, 07:50 PM
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Surging at cruising throttle

Hey fellas, looking for some thoughts.

My wifes superhawk is surging at cruising throttle.
Idle is fine, and acceleration is fine.
Have checked:
Throttle position sensor good
Carbies balanced & bowls drained
Plugs changed just in case
Battery good
Reg/rec good
No vacuume leaks
No jetting changes since running good
Fresh fuel

Any thoughts
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Old 05-26-2017, 09:14 PM
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surging is typically related to a lean condition. How does it run at higher engine speed? A torn diaphragm in the petcock can also cause fuel starvation and create a lean condition (had it happen to me a couple times)
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Old 05-26-2017, 09:31 PM
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I've had a torn petcock diaphram before and it starved for fuel at full noise. This is rich if anything.
It's strange, good one ride, then a month later **** from startup. Even in neutral holding rpm anywhere above idle it is surging.
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Old 05-27-2017, 08:03 AM
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I would more suspect torn carb diaphragm or carb boots not sealed tightly. Carb boot tears are tricky to find to look closely. Reseat the carbs themselves an smear a bit of Vaseline around the mating surface to help.

As it happens carefully pull the choke a bit to see what that does. It should change it somewhat.
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Old 05-27-2017, 08:04 AM
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More likely clogged carb jets. Take this time to install filters in the fuel lines. I would drain the fuel and start fresh when you clean the carbs or more gunk will simply reclog in like 2 blocks.
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Old 05-29-2017, 01:00 AM
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Watching this tentatively.
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Old 05-29-2017, 06:16 AM
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tentatively?

Like you can take or leave the outcome?
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