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Discussion Starter #1
Hi all- I am currently rebuilding my 722a carbs (from a '72 CL350) and noticed the tiny spring that holds the relief valve (not sure exactly what it is called) on the choke plate is snapped. This Means it is now free to move as it pleases.

Does anyone have any knowledge how this will affect the bike? Should it be replaced?

Any help would be appreciated. Thanks!!


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It may affect cold starts a little, that cylinder wont be richened as well as the other one by the choke.
 

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My OPINION differs........
IF the "loose" plate hangs down into the intake tract, it WILL affect how well the carb functions, albeit maybe not a massive amount....
The "fluttering" that would occur will cause a disturbance in the inflow of air (turbulence) reducing the slides lift and possibly allowing a lean mixture to be delivered to the cylinder.....
Complete removal of the "flap" plate would be preferable, with the possible "difficult starts" when using the choke resulting......JMHO....
 

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Discussion Starter #6
Thanks for the input!

So the loose valve/flap actually rests on top of the choke plate with the choke off (fully open). So it's actually not hanging down it the way off airflow and thus wouldn't really "futter." With this in mind I think it should be fine?

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I fix them frequently when I rebuild neglected carbs...

drill out the pin (it's peened over)

get a spring out of ball point pen and cut to length.

straighten out 1 coil on each end of the spring

reinstall (be careful to pay attention which way you spring the gate)

restake the pin so it doesn't come out.
 
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Simple aerodynamics:
Due to the longer air path over the plate (has to go up, over the 1/2 round bar, and across and past the raised section the flap itself creates) versus the flat lower edge of the open plate, Lift is created.... (much like an airplane wing, where the path over the wing is longer than the path under it)... This lift flutters the flap UNLESS overcome by the spring.....
 

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I fix them occasionally. Spring from ball point en is a little large wire diameter in my opinion.
Can't remember where I got the last couple of tiny spring, maybe old VCR or something similar as I didn't have to hunt for them online
 

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Discussion Starter #10
Thank you everyone for your input. I managed to repair it by re-bending the old spring and re-staking the pin back in place. Hopefully it will last!

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Well done that man :cool:
They are quite small pieces and fiddly to work with
 

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Hello all,

I have the same problem. Would someone please explain how to remove the pin. Also, what do you mean by "re-staking" the pin?

Thanks
 

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The only way I've found to get the pin out is to try and open the hole it was inserted in as much as possible with a specially ground punch then use a pin vice and small drill bits to drill it out a bit further. to actually get pin out.
When you fix everything you have to bash the post back to hold pin in place, it's called staking.
the part is only some sort of 'pot metal' and fairly easy to destroy if your not careful.
It's actually much easier to fit a replacement choke flap if you can find one. I have bought damaged carbs just to get a single piece if it's 'cost effective' as repairing original can take an hour or more.
 
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