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General Category => General Discussion => Topic started by: RogerGuzzi on July 07, 2016, 08:01:08 AM

Title: 78 Convert carburetor tech question
Post by: RogerGuzzi on July 07, 2016, 08:01:08 AM

My 1978 Convert was running very rich on the lefthand cylinder. The spark plug was fouling and now the cylinder is failing to fire. I believe that the float bowl may be overfilling. I have the carburetor off the cylinder (cables still attached), and am now wondering the next steps. Are there any step-by-step instructions or diagrams that I can use? Thanks in advance for any help.

Title: Re: 78 Convert carburetor tech question
Post by: Antietam Classic Cycle on July 07, 2016, 08:31:00 AM

Remove the cables and follow this procedure. http://www.thisoldtractor.com/moto_guzzi_loopframe_carburetor_rebuild_-__vhb.html

Could just be something as simple as not enough slack in the "choke" cable and/or a defective "choke" valve. The rubber disc on the tip may be cracked or just have too deep of an impression to seal off the enricher circuit completely.

(http://www.mgcycle.com/images/atrex/13937800.jpg)

Title: Re: 78 Convert carburetor tech question
Post by: RogerGuzzi on July 10, 2016, 05:39:30 PM

Thanks Antietam. One thing is that it was working fine one day and then the next this problem arose. So it wasn't something that wore gradually I think.

Title: Re: 78 Convert carburetor tech question
Post by: acogoff on July 10, 2016, 05:44:43 PM

     I would check as Antietam suggested first, then float inlet valve second. Sinking float third. Got good spark?

Title: Re: 78 Convert carburetor tech question
Post by: RogerGuzzi on July 10, 2016, 06:22:20 PM

Quote from: acogoff on July 10, 2016, 05:44:43 PM

Got good spark?

Thanks Acogoff. I will take your advice. Spark is good. Thank goodness, since electrics are not my strong point.

Title: Re: 78 Convert carburetor tech question
Post by: acogoff on July 10, 2016, 08:54:44 PM

     Also on the choke plunger, make sure the spring on top of it is able to push it back down to the bottom of the bore when the choke cable is released. I have seen one that had been sitting a while like to hang up.