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Hello y'all. Can anyone shine a little light on this for me? My dad and I have a pair of CA77 305s ('66 models?). Unfortunately we don't ride them enough. A few short runs a year, then we take them to ride around the Barbers Vintage Fest each year. It happens too often though. Ride em an hour or so, they start sputtering, not idling good, maybe even running on one cylinder. Pull the plugs and they're wet. I've moved the needle clip all the way to the top. Changed plugs to hotter D6HA's, instead of the manual recommended D8's. But what should I try next? Put a new set of plugs in and they're back ready to go and run amazingly! - for a while. But what can I do to make things better?
Could the needle seat be worn?
Adjust the air/fuel screw?
Are we just riding too slow?!
I've thought about investing in an electronic ignition from Charlie's Place. Would that help this?

Thanks in advance for any advice or recommendations!

Cheers,
Doug
 

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In your manual it should state how the plugs should be when they are taken out (to indicate if it is running lean, rich or optimal) or find a reference picture on google.
as this is properly the problem, you will need to adjust the Air/fuel mixture screw.
when the bike is tuned properly, it should work optimal no matter how slow or fast you ride. (overheating aside) it should run as good cold with choke as if it was warm without choke.
if you cannot get to the optimal sittings with the screw, the carburetor maybe just need to be cleaned, as you do say they do not get ridden much. (and fuel these days, don´t get me started)

adjust your air/fuel mixture screw until it gets around the optimal, remember to clean the spark plugs you can find a youtube video on how to do that.
if that is not enough you might need to clean the carburetors finding info on cleaning carburetors is easy as well. (if the fuel in your area contains much ethanol you might want to clean your carburetors before you start adjusting them)

since it is an old bike it might be time to do a rebuild of the carburetors, replacing old worn out parts. (to keep the insides clean doing storage time it might be an idea to use fuel stabilizer if the bikes are not drained from fuel)
on my carburetors i just open the float bowl and get a good idea needs to be cleaned. (usually easy to see if it is dirty, there will be a greenish layer, )
Sadly I only know VB carburetors and have little to none experience with other types. but it is universal how a good tuned bike should run.
this where my knowledge on the subject ends, but i am sure this forum can fill out the blanks.

hope this helps.
Soeren
 

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The mixture screws are adjusted at idle on a warm engine. With engine idling at the specified rpm (a timing light with a tach function is helpful here) adjust the screw to achieve the highest rpm. The number of turns out specified in the manual is just a starting point.

Another possibility is the float level, pretty easy to check/adjust.

Parts availability is limited on these old bikes, you might check in on "305.com" for more information.
 
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