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carb question for cb500

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neat street:
Hi all, the set of carbs have a choke leaver that is sprung loaded, so cannot be set at any intermediate setting (either on or off), question 1) can I change any parts from a spare set of cb750F1 carbs to make them more flexible? also when looking at them the choke is closed and is opened by the leaver? this I am sure is wrong? I have tried to look at the carb drawings on CMSIL, but cannot find a set the same as mine, or at least a full drawing with choke assembly showing spring orientation, are the srings on the carbs in the wrong way somehow?
thank you all for your help, John

florence:
I wonder if your carbs aren't standard because my chokes are operated by a small lever on the left side and it can be sited in any position from fully open to fully closed with no spring at all.

I will say though that fine adjustment has never been needed.  I start on full choke; within a few seconds I hear the engine revs start to decrease.  At this point, I open the chokes fully and engine runs normally.  This seems to be the case whatever the weather or temperature.  Once the engine is warm, no choke is required for subsequent restarts.

Maybe post a picture?

deltarider:

--- Quote from: florence on September 04, 2025, 09:47:21 AM ---[...] I start on full choke; within a few seconds I hear the engine revs start to decrease.  At this point, I open the chokes fully and engine runs normally.  This seems to be the case whatever the weather or temperature.  Once the engine is warm, no choke is required for subsequent restarts.

--- End quote ---
This ^ is the right procedure, also practised by me. The choke on this model is not supposed to be applied when riding.

Murf:
I have a USA 1975 K1 marked 022A on the right side carb inlet flange which are correct for the bike.  As with Florence my choke leaver is on the left and can be set in any position with down being full open. 
The springs that are on the choke system, 1 on each carb are arranged so they will help hold the choke closed but they cannot overcome the friction within the system,  so as I see it are just helpers and the leaver stays where you put it. Maybe all the bushes that the rods run through are very worn or missing on yours resulting in a lack of friction.

I would imagine the choke size (inlet diameter through the carb not actual choke) would be bigger on the 750 carbs and all jetting will be wrong for 550.

neat street:
Thank you again for your help, please see some pics of the carbs, note the springs which I would guess are put in wrong? As hopefully you can see the springs (x3) are keeping the choke closed. thanks again for your help.

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