CD12 skipping

[iron]

I have just finished rebuilding a 55 CD12 and after firing it up in a tank it seems to skip when taking it up to full throttle. The parts replaced were the rings, total ignition and gapped to 020, carb rebuild with new float and adjusted 1.5 turns slow needle and 1 turn high needle, lower unit sealed and impeller replacement. I have also rebuilt the pressure tank that holds pressure fine. Any thoughts?

 

[WillyBWright]

Re: CD12 skipping

1955 5.5Hp

Sounds like a gearcase problem. The cogs that mate the shifter (clutch dog) to the forward gear round-off and disengage under load. Unfortunately the only cure is replacement of the shifter and forwrd gear. But it could also be as simple as a shift adjustment, or a worn cradle. I'd look into those possibilities before assuming the worst.

 

[iron]

Re: CD12 skipping

I have also noticed this happining when in netural a few minutes ago. Could it be a fuel problem? I have checked both coils and the ignition seems fine, both cyls firing.

 

[MJ76]

Re: CD12 skipping

I think if it were a dog clutch slipping you'd describe it as a chattering or grinding noise. Have you adjusted the fuel needles, or just left them at their initial setting? I'm thinking possible lean condition. I would try richening it up a bit and see if that helps. Also, you mentioned you had rebuilt the tank. Be sure the lines and fittings aren't restricted, and that pressure is getting into the tank, as well as fuel getting out of it.

 

[Scaaty]

Re: CD12 skipping

I have a funny feeling its "sneezing", not skipping. Do you know the difference? Fatten up the gas..

 

[iron]

Re: CD12 skipping

The best way I can describe it is, when it is running it seems to flutter. The motor will run smooth and then it will what I feel is skipping. Think that is a fuel problem?

Thanks for the great site

 

[steelespike]

Re: CD12 skipping

Sounds to me like it is 4 cycling usually do to too rich high speed needle adjustment.
Your needle settings are just for initial startup.you need it on the boat for final adjustment.Adjust your highspeed with the motor warm at speed with the final setting just a touch toward rich.Then adjust the idle mixture warm in gear.These older motors sometimes will 4 cycle briefly when the throttle is first opened especially after extended trolling speed running.

 

[iron]

Re: CD12 skipping

I will try it on my boat as soon as the weather permits, when I do, I will take a video and post it if I still have any problems. I do have a short clip of it running if I can post it You can see what I am talking about

Thanks