Topic: Honda CB500 Four K1 choke lever wont stay down

[nuwonder]

Hi! I have a pretty extensively modified Honda Cb500 Four chopper, 1972 model I believe and it has developed during past couple years a peculiar problem: when bike is cold, the choke lever wont stay open (down) and closes itself (comes up) during riding,
effectively shutting down the bike if the choke is not manually pushed open again and held there. This seems to go away after riding a bike a bit and holding down the choke, then it stays down. But even riding to a bump or pothole can flip it back up.

What could be the cause of this? I assembled the bike maybe four years ago and it never had this problem back then. Have I put some spring backwards or is it a clearance problem which happens when carbs are cold but goes away when engine warms them?

The carb assemby is 100% factory, with only modifications being rejetting them and running K&N Pods on the carbs. I just synced them and after syncing the problem did not manifest for a week, but now it started doing it again. Could carbs going out of sync make something like this happen?

[Gurp]

Following

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[bryanj]

There should be a "pin" sticking out of the carb body that engages with a notch in the lever when at full movement, never know one come out but maybe

[nuwonder]

There should be a "pin" sticking out of the carb body that engages with a notch in the lever when at full movement, never know one come out but maybe

I presume this is when the lever is down and the choke is open? There is a stopper i think but I have to investigate for a pin.

[flatlander]

this may be a bit off beat but.... i had this mysterious problem for a while that the choke lever magically moved itself and thereby killed the engine while riding. turned out that the shafts of my new boots where exactly the hight that could flip the lever 

[Little_Phil]

There should be a "pin" sticking out of the carb body that engages with a notch in the lever when at full movement, never know one come out but maybe

I presume this is when the lever is down and the choke is open? There is a stopper i think but I have to investigate for a pin.

Never seen it but think it's a spring loaded ball that locates in dimple in the back of the lever when it's fully down.