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Author Topic: 77 CB750 with PD41A carbs...what are these little holes for?  (Read 946 times)

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Offline Sprocket75

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77 CB750 with PD41A carbs...what are these little holes for?
« on: October 10, 2017, 07:36:11 AM »
Last night I removed the crabs again to clean and finish tuning them. (needle jet clips)  Anyway, while I had them apart, I was blowing compressed air through the orifices etc. and I noticed these tiny holes on the body of the carbs where the slides are. (*See RED circle in photo) Each one has one of these. When blowing compressed air, I noticed that air comes out of these tiny holes as well. Can anyone tell me what these are for?
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..."Always two there are, no more, no less. A master and an apprentice"... YODA

1975 Honda CB550K

Offline flybox1

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Re: 77 CB750 with PD41A carbs...what are these little holes for?
« Reply #1 on: October 10, 2017, 08:27:39 AM »
Atmospheric vents
They are there so air can move in and out of the float bowl to allow fuel levels to, well, stay level.  ;D
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'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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Offline Sprocket75

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Re: 77 CB750 with PD41A carbs...what are these little holes for?
« Reply #2 on: October 10, 2017, 08:38:14 AM »
Thanks Flybox...  was just curious more than anything. 
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..."Always two there are, no more, no less. A master and an apprentice"... YODA

1975 Honda CB550K

Offline Bodi

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Re: 77 CB750 with PD41A carbs...what are these little holes for?
« Reply #3 on: October 10, 2017, 08:49:55 AM »
They are a sort of backup vent in case the bowl vent tubes get blocked or pinched.
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