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1978 CB550 K4 carb choke spring

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Brian Cairns:

--- Quote from: Seabeowner on January 19, 2024, 06:54:22 PM ---If this is a USA import then I believed that the 1978s had PD46C like mine has. But maybe they were just using up bits as it was the end of the line. The main throttle spring is mounted round the throttle shaft on the PD46C.
But back to the choke shaft. I  am not going to be much help. But think the C and A both have the double spring arrangement. When I split my carbs a few years ago I remember that getting that spring wound to give the correct force was a a nightmare so take note how much it unwinds when it lets go.

--- End quote ---

Hi just wondering what float height and needle position do you use on the PD46C carbs...........since I will be taking carbs of bike I am going to check everything out....can't get bike above 70 mph and am convinced its something to do with carbs. Everything on bike is standard.

Cheers

Brian

Seabeowner:

--- Quote from: Brian Cairns on January 20, 2024, 11:03:26 AM ---
--- Quote from: Seabeowner on January 19, 2024, 06:54:22 PM ---If this is a USA import then I believed that the 1978s had PD46C like mine has. But maybe they were just using up bits as it was the end of the line. The main throttle spring is mounted round the throttle shaft on the PD46C.
But back to the choke shaft. I  am not going to be much help. But think the C and A both have the double spring arrangement. When I split my carbs a few years ago I remember that getting that spring wound to give the correct force was a a nightmare so take note how much it unwinds when it lets go.

--- End quote ---

Hi just wondering what float height and needle position do you use on the PD46C carbs...........since I will be taking carbs of bike I am going to check everything out....can't get bike above 70 mph and am convinced its something to do with carbs. Everything on bike is standard.

Cheers

Brian

--- End quote ---
I have written down 14.5mm for the A and 12.5mm for the C. Strange really as think they are same carbs. So 12.5mm. Only covered about 75miles though as only got it legal late last year.

Brian Cairns:

--- Quote from: Seabeowner on January 20, 2024, 06:55:52 PM ---
--- Quote from: Brian Cairns on January 20, 2024, 11:03:26 AM ---
--- Quote from: Seabeowner on January 19, 2024, 06:54:22 PM ---If this is a USA import then I believed that the 1978s had PD46C like mine has. But maybe they were just using up bits as it was the end of the line. The main throttle spring is mounted round the throttle shaft on the PD46C.
But back to the choke shaft. I  am not going to be much help. But think the C and A both have the double spring arrangement. When I split my carbs a few years ago I remember that getting that spring wound to give the correct force was a a nightmare so take note how much it unwinds when it lets go.

--- End quote ---

Hi just wondering what float height and needle position do you use on the PD46C carbs...........since I will be taking carbs of bike I am going to check everything out....can't get bike above 70 mph and am convinced its something to do with carbs. Everything on bike is standard.

Cheers

Brian

--- End quote ---
I have written down 14.5mm for the A and 12.5mm for the C. Strange really as think they are same carbs. So 12.5mm. Only covered about 75miles though as only got it legal late last year.

--- End quote ---

Yes I read 12.5mm for the C. going to check them tomorrow.
I think the wrong main jet size is wrong in my bike, should be 90 but has 98 installed. I was also told that  the needle height on the C carbs can't be adjusted i.e. only has one notch but again will check that also?

Cheers

Brian

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