Oh...on a side note, the sled is a 1975 year model. Not a 74 as originally posted, my bad.

Yes. You are correct about the white thick smoke. Never would have thought about that. Now I gotta order more parts. Just ordered cdi , regulator and coil, but I guess it won't hurt to have extras. Although I am not a mechanic, and appreciate the advice, wouldn't the leaky seal cause it to more sput...

Hi all. Newbie to the sledding world. I recently bought a very clean low mileage 1975 JD 400. It has a KEC 340 engine. I have rebuilt and cleaned carb. It fires right up, runs like a top for about 10 to 15 minutes, then without warning just bogs out and dies when throttling . It will fire right back...